kpi framework for maintenanceltu.diva-portal.org/smash/get/diva2:1315950/fulltext02.pdfkpi framework...
TRANSCRIPT
Esi Saari
Operation and Maintenance Engineering
Department of Civil, Environmental and Natural Resources EngineeringDivision of Operation, Maintenance and Acoustics
ISSN 1402-1544ISBN 978-91-7790-400-7 (print)ISBN 978-91-7790-401-4 (pdf)
LuleΓ₯ University of Technology 2019
DOCTORAL T H E S I S
Esi Saari K
PI framew
ork for maintenance m
anagement through eM
aintenance
KPI framework for maintenancemanagement through eMaintenance
Development, implementation, assessment, and optimization
KPI framework for maintenance management through eMaintenance Development, implementation, assessment, and optimization
Esi Saari
Operation and Maintenance Engineering
Printed by LuleΓ₯ University of Technology, Graphic Production 2019
ISSN 1402-1544 ISBN 978-91-7790-400-7 (print)ISBN 978-91-7790-401-4 (pdf)
LuleΓ₯ 2019
www.ltu.se
i
ACKNOWLEDGEMENTS
The research presented in this thesis was carried out by the Operation and Maintenance Engineering division at LuleΓ₯ University of Technology (LTU), Sweden.
First of all, I would like to thank LKAB for providing funding, data and other assistance, specifically, Peter Olofsson, Mats Renfors, Sylvia Simma, Maria Rytty, Mikael From and Johan Enbak, who were involved in initiating and supporting this project.
Next, I would like to express my profound gratitude to the project leader who doubles as my assistant supervisor, Professor Ramin Karim, for giving me the opportunity to be a part of the research and for providing his guidance throughout the research.
I would also like to thank my main supervisor Associate Professor Jing Lin (Janet Lin). I would not be here today without her tremendous help. I am very grateful for her patience, understanding and guidance even in the short time we worked together.
I am thankful to Professor Aditya Parida who was initially my main supervisor. Even after he left, he still guided and supported me. A big thank you to Associate Professor Phillip Tretten for his help, guidance and words of encouragement in times when I felt I could not continue. I also thank Professor Uday Kumar for his comments, contributions and guidance.
I appreciate the support of Professor Diego Galar, Dr. Liangwei (Levis) Zhang, Dr. Stephen Famurewa, Dr. Christer StenstrΓΆm and other faculty members.
Great thanks are due to my loving husband John and our daughter Johanna for their understanding and support. Thanks to Mrs. Philomina Owusu-Obeng for her prayers and words of encouragement and for being the mother I never had. I would like to thank my siblings and parents-in-law, Mats and Eva Saari, for their encouragements.
A big thank you also to the wonderful brethren who supported me with their prayers and encouraging words, Dr. Obudulu Ogonna, Dr. Samuel Awe, Abiola Famurewa, Andrews Omari and Emefa Omari.
Finally, all of my help comes from God, who gives life and hope to the hopeless, the eternal creator and giver of wisdom and grace for this time and in the eternal life.
Esi Saari
June 2019
LuleΓ₯, Sweden
ii
iii
ABSTRACT
Performance measurement is critical if any organization wants to thrive. The motivation for the thesis originated from the project βKey Performance Indicators (KPI) for control and management of maintenance process through eMaintenance (in Swedish: Nyckeltal fΓΆr styrning och uppfΓΆljning av underhΓ₯llsverksamhet m h a eUnderhΓ₯ll)β, initiated and financed by a mining company in Sweden. The main purpose of this project is to propose an integrated KPI system for the mining companyβs maintenance process through eMaintenance, including development, implementation, assessment, and optimization.
There are gaps in the research, however, resulting in the following challenges. First, no KPI framework considers both technical and soft KPIs, so developing a system is problematic. Second, few studies have focused on implementing KPI measurement through eMaintenance. Third, there are gaps in KPI assessment. In assessing system availability, for example, the current analytical (e.g., Markov/semi-Markov) or simulation approaches (e.g., Monte Carlo simulation-based) cannot handle complicated state changes or are computationally expensive. In addition, few researchers have revealed the connections between technical and soft KPIs. For those soft KPIs for which the distribution of data collected from eMaintenance systems (e.g., work orders) is not easily determined, studies are insufficient. Fourth, the current continuous improvement process for the KPIs is very time-consuming. In short, there is a need for a new approach.
The thesis develops an integrated KPI framework consisting of technical KPIs (linked to machines) and soft KPIs (linked to maintenance workflow) to control and monitor the entire maintenance process to achieve the overall goals of the organization. The proposed KPI framework makes use of four hierarchical levels and has 134 KPIs divided into technical and soft KPIs as follows: asset operation management has 23 technical KPIs, maintenance process management has 85 soft KPIs and maintenance resources management has 26 soft KPIs.
The thesis discusses the proposed KPI framework; it lists the KPIs and provides timelines, definitions and general formulas for each specified KPI. Results will be used by the mining company to guide the implementation of the proposed KPIs in an eMaintenance environment.
To suggest novel approaches to KPI assessment, the thesis takes system availability in the operational stage as an example. It proposes parametric Bayesian approaches to assess system availability. With these approaches, Mean Time to Failure (MTTF) and Mean Time to Repair (MTTR) can be treated as distributions instead of being βaveragedβ by point estimation. This better reflects reality. Markov Chain Monte Carlo (MCMC)
iv
approach is adopted to take advantage of both analytical and simulation methods. Because of MCMCβs high dimensional numerical integral calculation, the selection of prior information and descriptions of reliability/maintainability can be more flexible and realistic. The limitations of data sample size can also be compensated for. In the case studies, Time to Failure (TTF) and Time to Repair (TTR) are determined using a Bayesian Weibull model and a Bayesian lognormal model, respectively. The proposed approach can integrate analytical and simulation methods for system availability assessment and could be applied to other technical problems in asset management (e.g., other industries, other systems). By comparing the results with and without considering the threshold for censoring data, the research shows the connection between technical and soft KPIs, and suggests the threshold can be used as a monitoring line for continuous improvement in the mining company. For those soft KPIs for which the distribution of data collected from the eMaintenance system (e.g., work orders) is not easily determined, other approaches, such as time series analysis (if the data are βfast movingβ), the Croston method (if the data are βintermittentβ), or the bootstrap method (if the data are βslow movingβ) could be applied.
To ensure the KPI framework can be improved continuously, the thesis performs a comparison study to find the gaps between current and proposed KPIs in the mining company. It adapts a roadmap from the railway industry to show how optimization can be promoted by reviewing and improving the KPI framework.
Results from this study will be applied to the company and guide its development, implementation and assessment of the KPIs through eMaintenance with continuous improvement. The proposed approaches could also be applied to other technical problems in asset management (e.g., other industries, other system).
Keywords: maintenance engineering, maintenance performance measurement, Key Performance Indicator (KPI), eMaintenance, mining industry.
v
ACRONYMS
ACF Auto-correlation function AD Anderson-Darling ARMA Autoregressive Moving Average ARIMA Autoregressive Integrated Moving Average CM Corrective maintenance DSS Decision support system FAR False alarm rate GRB Gelmen-Rubin-Brooks HPD Highest Posterior Distribution HSE Health Safety Environment IT Information Technology ICT Information and Communications Technology KPIs Key performance indicators KRA Key result area MA Maintenance Analytics MC error Monte Carlo error MCMC Markov Chain Monte Carlo MDT Mean down time MES Manufacturing execution system MPIs Maintenance performance indicators MPM Maintenance performance measurement MTBF Mean Time between Failure MTTF Mean Time to Failure MTTR Mean Time to Rapair OEE Operational Equipment Effectiveness PACF Partial auto-correlation function PDCA Plan-Do-Check-Act PdM Predictive Maintenance PI Performance indicators PM Preventive Maintenance RCA Root Cause Analysis ROI Return on Investment RQ Research Question RTF Run to Failure SBA Syntetos-Boylan Approximation SBJ Shale-Boylan-Johnston
vi
SIQ Swedish Institute for Quality TBF Time between Failure TDU Total report operation and maintenance TSB Teunter, Syntetos and Babai TTF Time to Failure TTR Time to Repair
vii
CONTENTS
PartIβComprehensiveSummary
CHAPTER1.INTRODUCTION 11.1 Background 1 1.1.1KPIsandMPMframework 1 1.1.2OntologyandtaxonomyineMaintenance 3 1.1.3KPIOntologyandtaxonomy 4 1.1.4Projectmotivation 6 1.2 Problem statement 9 1.3 Purpose and objectives 10 1.4 Research questions 10 1.5 Linkage of research questions and appended papers 11 1.6 Scope and limitations 12 1.7 Authorship of appended papers 12 1.8 Outline of thesis 13
CHAPTER2.THEORETICALFRAMEWORK 152.1 eMaintenance and maintenance decision-making 15 2.2 Performance measurement 17 2.3 Maintenance performance measurement 20 2.4 KPI assessment 21 2.4.1 Systemavailabilityassessment 21 2.4.2 Somequantitativeapproaches 22 2.5 Summary of research framework 27
CHAPTER3.RESEARCHMETHODOLOGY 293.1 Research design 29 3.2 Data collection 31 3.2.1 Interview 31 3.2.2 Documentationfromstudiedcompany 31 3.2.3 Datasource:operationandmaintenancedata 31 3.3 Literature review 31 3.4 Data analysis 32 3.4.1DataanalysisinPaperB 32 3.4.2DataanalysisinPaperC 35 3.5 Reliability and validity of the research 38
viii
3.6 Induction, deduction and abduction 40
CHAPTER4.SUMMARYOFTHEAPPENDEDPUBLICATIONS 414.1 Paper A 41 4.2 Paper B 41 4.3 Paper C 42
CHAPTER5.RESULTSANDDISCUSSION 455.1 Results and discussion related to RQ1 45 5.1.1KPIframework 45 5.1.2DevelopmentofassetoperationmanagementKPIs 47 5.1.3DevelopmentofmaintenanceprocessmanagementKPIs 49 5.1.4DevelopmentofmaintenanceresourcemanagementKPIs 56 5.2 Results and discussion related to RQ2 58 5.2.1KPIimplementationforassetoperationmanagement 58 5.2.2KPIimplementationformaintenanceprocessmanagement 60 5.2.3KPIimplementationformaintenanceresourcemanagement 68 5.3 Results and discussion related to RQ3 71 5.3.1AssessmentoftechnicalKPIs 71 5.3.2AssessmentandconnectionsoftechnicalandsoftKPIs 75 5.3.3AssessmentofsoftKPIs 84 5.4 Results and discussion related to RQ4 92 5.4.1ComparisonofcurrentandproposedKPIs 92 5.4.2OptimizationoftheproposedKPIs 94
CHAPTER6.CONCLUSIONS,CONTRIBUTIONSANDFUTURERESEARCH 976.1 Conclusions 97 6.2 Contributions 99 6.3 Future research 99
REFERENCES 101
APPENDIX 107
PartIIβAppendedPapers
PaperA
PaperB
PaperC
ix
LISTOFAPPENDEDPAPERS
PaperA
Saari, E., Sun, H-L., Lin, J. and Karim, R. 2019. Development and implementation of a KPI framework for maintenance management in a mining company. Journal of SystemAssuranceEngineeringandManagement.Under Review.
PaperB
Saari, E., Lin, J., Zhang, L-W, Liu B and Karim, R. 2019. System availability assessment using a parametric Bayesian approach β a case study of balling drums. InternationalJournalofSystemAssuranceEngineeringandManagement.Accepted.
PaperC
Saari, E., Lin, J., Liu B, Zhang, L-W and Karim, R. 2019. A novel Bayesian approach to system availability assessment using a threshold to censor data. InternationalJournalofPerformabilityEngineering.Published.
LISTOFRELATEDPUBLICATIONS
Nunoo, E., Phillip, T. and Parida, A. 2014. Issues and challenges for condition assessment: A case study in mining. Proceedingsofthe3rd internationalworkshopandcongressoneMaintenance:June17β18,LuleΓ₯,Sweden.pp:85β93.
Saari, E., Lin, J. and Karim, R. 2018. Development of KPI framework for maintenance process management through eMaintenance β A study for LKAB. Research Report. Approved by LKAB.
x
PartI
ComprehensiveSummary
KPI framework for maintenance management through eMaintenance
1
Chapter1Introduction
This chapter gives a short description of the research background of the thesis, states the research problems, enumerates the research purpose, objectives and questions, and explains the research scope, limitations, and structure.
1.1 Background
Description of this section consists of both theoretical background and practical background as shown in Figure 1.1, after which the problem statement is summarized in the next section.
PI, KPI,MPI, MP, MPM framwork
(See 1.1.1)
Maintenance, eMaintenance, Ontology
and Taxonomy (See 1.1.2)
KPI Ontology and Taxonomy
(See 1.1.3)
Project motivation,Mining company,Current situation
(See 1.1.4)
1.2 Problem statement Theoretical Background
Practical Background
Figure 1.1 Theoretical and practical background
1.1.1KPIsandMPMframework
Performance indicators (PIs) are numerical or quantitative indicators that show how well an objective is being met (Pritchard et al., 1990). PIs highlight opportunities for improvement within companies and are applied to find ways to reduce downtime, costs and waste, operate more efficiently, and get more capacity from the operational lines (Parida, 2006). PIs also provide measures of how many resources are being used in relation to available ones, access the extent to which management targets are met and evaluate the general impact of management strategies (Alegre et al., 2017).
PIs can be classified as leading or lagging indicators. Leading indicators warn users about objectives beforehand; thus, they work as performance drivers and support a specific organizational unit in ascertaining the present status in comparison with an acceptable reference. A lagging indicator indicates condition after the performance has
Chapter 1 Introduction
2
taken place; e.g., maintenance cost per unit (Parida, 2006). As rule, all PIs are tied to long-range corporate business objectives.
When aggregated to the managerial or higher level, PIs at the shop floor level or functional level are called key performance indicators (KPIs). A KPI can indicate the performance of a key result area (KRA). KPIs focus on those aspects of organizational performance that are the most critical for the current and future success of the organization (Parmenter, 2007). They evaluate whether organizational targets have been reached. Unlike PIs, which are mostly general measures, KPIs measure what the organization considers most important. For this reason, some organizations may use a KPI that another company considers a PI and vice versa.
Maintenance performance indicators (MPIs) are used to evaluate the effectiveness of maintenance carried out (Wireman, 2005). The attributes and concept of performance measurement are relevant to maintenance performance measurement (MPM) if a holistic approach is adopted for maintenance, and it is considered part of the business performance. An MPM framework needs to facilitate and support management in controlling and monitoring the performance aligned to the organizational objectives and strategy to permit timely corrective decisions. The framework needs to provide a solution for performance measurements by linking them directly with the organizational strategy and considering criteria consisting of both financial and non-financial indicators (Parida & Kumar, 2006). The link-and-effect model of MPM framework can achieve total maintenance effectiveness, i.e., both external and internal (see Figure 1.2), thus contributing to the overall objectives of the organization and its business units (Parida, 2006).
StrategicLevel Societal responsibility Transparency Good governance
TacticalLevel ROI & Cost effectiveness Life cycle asset utilization Safe environment
OperationalLevel Availability Reliability Capacity
Business Integrity Index (BII)
Asset Integrity Index (AII)
Process Integrity Index (BII)
ROI & HSE
Unsolved conflict
OEENo.Incident/
accident
Relationship of Coustomer &
Employee conflict
Health & safety (No. Incident/accident)
Organization, Engineering, Supply chain management
Objectively measure data from operational to strategical level
MPIs derived from strategical to operational level
Figure 1.2 Link-and-effect model1 (Parida, 2006)
1 Notes in Figure 1.2: ROI-Return on Investment; HSE-Health Safety Environment; OEE-Operational Equipment Efficiency.
KPI framework for maintenance management through eMaintenance
3
An MPM framework is needed to meet the eMaintenance requirements of organizations, stakeholders, and the maintenance department in some cases (Parida, 2006).
1.1.2OntologyandtaxonomyineMaintenance
eMaintenance is defined as the materialization of information logistics aimed to support maintenance decision-making (Karim, 2008; Kajko-Mattson et al., 2011). Its solutions integrate information and communications technology (ICT) with maintenance strategies, creating innovative ways to support production (e-manufacturing) and business (e-business) (Koc & Lee, 2003; Muller, Crespo Marque, & Iung, 2008).
eMaintenance solutions are essentially data-driven. Thus, an effective maintenance decision-making process needs a trusted decision support system (DSS) based on knowledge discovery, defined as data acquisition, data transition, data fusion, data mining, information extraction and visualization (Kans & Galar, 2017; Karim et al., 2016).
Since eMaintenance data are often transferred between heterogeneous environments, eMaintenance solutions must have interconnectivity. All systems within the eMaintenance network must interact as seamlessly as possible to exchange information in an efficient and usable way (Aljumaili, 2016). However, in reality, not all data are processed and turned into information; some say there are too many data and too little information (Galar & Kumar, 2016). In the era of Maintenance 4.0, the lack of efficient Information Technology (IT) support adversely affects the planning and optimization of maintenance (Kans & Galar, 2017).
See Figure 1.3, incorporating principles of ontology and taxonomy into eMaintenance solutions will facilitate strategic asset management (Kans & Galar, 2017) and promote maintenance analytics (Karim, et al., 2016).
Figure 1.3 Ontology and Taxonomy in eMaintenance
Chapter 1 Introduction
4
In philosophy, ontology is the study of the nature of being, existence, or reality; in computer science, ontology is a special kind of information object or computational artefact (Rachman, 2019). In eMaintenance, ontologies are represented by the published standards that can be used to support maintenance. These standards offer some stability by proposing information models for data representation, an essential property for long-term data exchange and archiving (Aljumaili, 2016). An ontology model can be described as a set O C, RS, I . In this model, C is a collection of concepts also called classes, I is set of particulars (instances of classes, individuals), and RS is the set of relationships between two concepts or particulars (Schmidt, 2018).
Taxonomy is a hierarchical classification system, often depicted as a tree that starts from a root concept and progressively divides into more specific off-shoot concepts. In eMaintenance, taxonomy refers to the type of relationships among the data.
It is essential to understand the ontology and taxonomy of KPIs if data are to be transformed from information into the knowledge required to develop, implement, assess, and optimize a KPI framework for maintenance management through eMaintenance.
1.1.3KPIontologyandtaxonomy
KPI ontology supports the construction of a valid reference model that integrates KPI definitions proposed by different engineers in a minimal and consistent manner to increase interoperability and collaboration (Diamantini et al., 2014). Several KPI ontology models have been proposed in the literature in the context of the performance-oriented view of organizations (Popova & Alexei, 2010; Del-RΓo-Ortega et al., 2010; Del-RΓO-Ortega et al., 2013; Negri et al., 2015). These models dwell on description logic and first-order sorted predicate logic to express on an axiomatic basis the relations among indicators, using concepts like causing,correlatedandaggregation_of. However, some argue that these models do not take compositional semantics into account. Furthermore, the models are conceived to define KPIs in a single process-oriented enterprise, and the issue of consistency management is not taken into account.
Diamantini et al. (2014) have considered compositional semantics in developing their KPI model. The proposed method serves as a formal way of describing indicators, with the core of the ontology composed of a set of disjoint classes, detailed as indicator, dimension and formula.
Indicator signifies the key class of the KPI ontology, while its instances (i.e., indicators) describe the metrics enabling performance monitoring. Properties of the indicator include name, identifier, acronym, definition (i.e., a detailed description of meaning and usage), compatible dimensions, formula, unit of measurement chosen for the indicator, business object and aggregation functions.
Dimension is the coordinate or perspective along which a metric is computed; it is structured into a hierarchy of levels, where each level represents a different way of grouping elements of the same dimension.
KPI framework for maintenance management through eMaintenance
5
Figure 1.4 a fragment of the Indicator taxonomy: an example (Diamantini et al, 2014)
Figure 1.5 properties of indicator PersonnelTrainingCosts: an example (Diamantini et al, 2014)
Formula is an algebraic operation used to express the semantics of the indicator. It describes the way the indicator is computed and is characterized by the aggregation function, the way the formula is presented, the semantics (i.e., the mathematical meaning) of the formula, and references to its components, which are, in turn, formulas of indicators.
Chapter 1 Introduction
6
According to Diamantini et al. (2014), KPI composite indicators can be represented in a tree structure and calculated with full or partial specification of the formula linking the indicator to its component. Figure 1.3 indicates a sample fragment of KPI taxonomy; Figure 1.4 shows an example of properties of the indicator called PersonnelTrainingCosts and an excerpt of the hierarchies for organization and time dimensions (Diamantini et al., 2014).
1.1.4Projectmotivation
The motivation for the research was the project βKey Performance Indicators (KPIs) for control and management of maintenance process through eMaintenance (in Swedish: Nyckeltal fΓΆr styrning och uppfΓΆljning av underhΓ₯llsverksamhet m h a eUnderhΓ₯ll)β, initiated and financed by a Swedish mining company. The main purpose of this project is to propose an integrated KPI system for the mining companyβs maintenance process through eMaintenance, including development, implementation, assessment, and optimization.
The companyβs maintenance policy focuses on full capacity utilization, with utilization rate and plant speed considered critical to profitability. The company assesses its success by analysing utilization, availability, and error rate data gathered by one asset management system in the studied company called βPlant Performance/IP21β. As a result, most of its existing KPIs measure maintenance performance relative to the equipment condition with a few KPIs measuring maintenance planning and maintenance execution, as shown in Figure.1.6.
The companyβs mission for its maintenance process is to have equipment functioning in an agreed-upon manner. Getting equipment running at full capacity and in an agreed-upon manner requires in-depth knowledge of the equipment and the maintenance process. The company has divided its maintenance process into three levels as shown in Figure 1.6. All numbers in the figure correspond to sections in the maintenance handbook that explain in detail what the numbers mean.
Level 1 encompasses systematically developed maintenance needs to control maintenance work, level 2 encompasses mastering and assembling all work from the minimum maintenance work to the introduction of continuous improvements to control the equipment, and level 3 encompasses control over strategic processes.
KPI framework for maintenance management through eMaintenance
7
Figure 1.6 Maintenance process in the mining company2
2 Notes in Figure 1.6: PM-Preventive Maintenance; CM-Corrective Maintenance; SIQ-Swedish Institute for Quality.
Chapter 1 Introduction
8
Simply put, the three levels include introducing working methods, measuring the effect of the work, adjusting the content of the tasks to give the correct effect and working together internally (workplaces, professions) and externally (collaboration with suppliers, other companies and organizations working with the company) to achieve coordination benefits. The company needs an integrated KPI framework because the data gathered are not being optimally used for decision making. Very few KPIs are in use and some KPIs do not work for all three company plants; for example, the speed loss KPI only worked in system KK4 at the time of this report.
In addition to Plant Performance/IP21, the company uses other asset management systems like Movex, LIMS, productions ledger, etc. to collect and store data for later analysis and decision making. New KPIs need to be developed and integrated with existing KPIs to measure efficiency in the maintenance process and to support effective decision making to promote full capacity utilization.
In the studied company, KPI framework comprises two parts3: technical KPIs (linked to machines) and business KPIs (linked to workflow); the latter ones are also called soft KPIs based on the business strategies of the company. Soft KPIs affect technical KPIs in the long run and, thus, can increase or decrease utilization and plant speed. Soft KPIs also affect production KPIs and even the companyβs KPIs, as shown in Figure 1.7. The right KPIs can direct decision makers to address maintenance needs and other types of improvement work on equipment, maintenance personnel and the maintenance process as a whole.
Figure 1.7 Current KPI structure in the studied company
To improve KPIs and keep them relevant, the company uses the Plan-Do-Check-Act (PDCA) cycle, internally referred to as the βimprovement wheelβ. The PDCA cycle is similar to Neelyβs PDCA cycle for performance measurement shown in Figure 1.3. Both methods help to keep measures alive and relevant.
3 The definitions of technical and business (soft) KPIs follow internal rules of the studied mining company.
KPI framework for maintenance management through eMaintenance
9
Figure 1.8 illustrates the maintenance, execution, follow-up and analysis of the maintenance plan, as well as continuous improvements. Each section in the cycle shows what is required to achieve the main objective of that part of the cycle.
Figure 1.8 PDCA cycle for maintenance improvement
1.2Problemstatement
As discussed above, new multifaceted challenges in the mining company require the development of an integrated KPI framework for maintenance management in an eMaintenance environment. Based on the discussions in Chapter 1 and later in Chapter 2, the problems identified in an initial exploratory study include the following:
Chapter 1 Introduction
10
Problem1:Lack of a KPI framework for maintenance management considering technical and soft KPIs;
Problem 2: Lack of a specified approach to guide implementation of the developed KPI framework through eMaintenance;
Problem 3: Lack of quantitative approaches for KPI assessment for either technical or soft KPIs;
Problem4: Lack of an optimization approach for a developed KPI framework to optimize it continuously.
1.3Purposeandobjectives
To deal with these problems, the main purpose of this research is to develop and assess an integrated KPI framework for maintenance management in an eMaintenance environment to achieve the overall goals of the organization.
More specifically, the research objectives include:
Objective1:Developing a KPI framework for maintenance management; Objective2: Developing a KPI implementation approach in an eMaintenance
environment which can be improved continuously; Objective3: Developing novel approaches to assessing both technical and soft
KPIs.
The main connections between the problems summarized in Section 1.2, and the research objectives are shown in Table 1.1.
Table 1.1 Connections between problems and objectives
Problems Objective 1 Objective 2 Objective 3
1 X
2 X X
3 X
4 X
1.4Researchquestions
To achieve the stated purpose and objectives, the following research questions have been formulated:
Researchquestion1: What is a KPI framework for maintenance management? Researchquestion2: How can the developed KPI framework be implemented
through eMaintenance? Researchquestion3: How can the KPIs be assessed using novel approaches?
KPI framework for maintenance management through eMaintenance
11
Research question 4: How can the developed KPI framework be improved continuously?
The research questions are formulated to achieve the research objectives presented in Section 1.3.
For research question 3, three sub-questions are formulated:
Research question 3.1: How can technical KPIs be assessed using a novel approach?
Research question 3.2: How can technical and soft KPIs be assessed and improved together using a novel approach?
Research question 3.3: How can soft KPIs be assessed using a novel approach?
The main connections between the research questions and research objectives are shown in Table 1.2.
Table 1.2 Connections between RQs and objectives
Research questions (RQs) Objective 1 Objective 2 Objective 3
RQ1 X X
RQ2 X
RQ3
RQ3.1 X
RQ3.2 X
RQ3.3 X
RQ4 X
1.5Linkageofresearchquestionstotheappendedpapers
The links between the research questions (RQs) and the appended papers and the PhD thesis, are presented in Table 1.3. RQ1 is answered in Paper A and Chapter 5.1 in the thesis. RQ2 is explored in Paper A and Chapter 5.2. RQ3.1 is addressed in Paper B; RQ3.2 is addressed in Paper C; RQ3.3 is addressed in Chapter 5.3 of the thesis. Finally, RQ4 is explored in Chapter 5.4 of the thesis.
Chapter 1 Introduction
12
Table 1.3 Linkage of RQs and appended papers
Research questions (RQs) Paper A Paper B Paper C PhD thesis
RQ1 X X
RQ2 X X
RQ3
RQ3.1 X X
RQ3.2 X X
RQ3.3 X
RQ4 X
1.6Scopeandlimitations
This scope of this research is the study of an integrated KPI framework for maintenance management in an eMaintenance environment. The research covers KPI development, implementation, assessment, and optimization. Specifically, this research develops a four-level KPI framework with 134 indicators for a mining company. It explores the implementation of each proposed KPI in mining environment. Since the research was motivated/financed by a particular mining company, the technical KPIs (linked to machines) and soft KPIs (linked to workflow) are developed based on companyβs business strategies.
The limitations of the thesis are the following:
First, the link-and-effect model are not dealt with in this study; Second, costs are not considered sufficiently, as other departments are not
included in the project; Third, the emphasis is on developing a new KPI assessment, so the research uses
only a few KPIs as examples because of time and project limitations; Fourth, the proposed KPIs are general. KPIs for different/specified plants,
processes, maintenance tasks (e.g., condition morning, lubrication, etc.) are not studied separately.
Further work is required to minimize these limitations.
1.7Authorshipofappendedpapers
The content of this section has been accepted by all authors who contributed to the papers and the thesis. The contribution of each author with respect to the following activities is shown in Table 1.4:
1. Formulating the fundamental ideas of the problem (initial idea and model development);
2. Collecting data;
KPI framework for maintenance management through eMaintenance
13
3. Performing the study; 4. Drafting the paper; 5. Revising important intellectual contents; 6. Giving final approval for submission.
Table 1.4 Linkage of RQs and appended papers
Authors Paper A Paper B Paper C Thesis
Esi Saari 1 - 6 1 - 6 1 - 6 1 - 6
Jing (Janet)Lin 1, 5, 6 1, 5, 6 1, 5, 6 1, 5, 6
Ramin Karim 1, 5, 6 5, 6 5, 6 1, 5, 6
Hunling (Natalie)Sun 3, 5 / / /
Liangwei (Levis) Zhang / 5 5 /
Bin Liu / 5 5 /
1.8Outlineofthesis
This thesis consists of two parts. The first part summarizes the subject and research and discusses the appended papers, extensions of the research and conclusions. The second part consists of three appended papers.
More specifically, Chapter 1 provides background information on the relevance of this research and its contextual perspective. The chapter introduces the research problem, describes the research purpose, introduces the research questions and explains the scope, limitations and structure. The theoretical framework is presented in Chapter 2. The chapter gives an overview of maintenance performance measurement, KPI implementation through eMaintenance and related areas in the mining industry and quantitative approaches to KPI assessment. Chapter 3 presents the research methodology, including research design, data collection, literature review and data analysis Chapter 4 summarizes the three appended publications. Chapter 5 presents the results and discusses the research. Finally, Chapter 6 gives the findings, explains the contribution of the research and suggests future work.
The first appended paper develops a KPI framework to control and monitor the maintenance process to achieve the studied companyβs overall goals. This KPI framework comprises two parts: technical KPIs (linked to machines) and business KPIs (linked to workflow); the latter ones are also called soft KPIs based on business strategies of the mining company. The developed KPI framework has four levels. The second level includes asset operation management with KPIs measuring maintenance performance relative to the equipment condition, maintenance process management with KPIs measuring the efficiency and effectiveness of the consistent application of
Chapter 1 Introduction
14
maintenance and maintenance support and maintenance resources management with KPIs measuring spare part management, internal maintenance personnel management and external maintenance personnel management. The third level breaks down the items on the second level, and the fourth level includes the KPIs that are made up of the third level classifications. In all, the framework includes 134 KPIs to measure maintenance performance and streamline maintenance processes. Twenty-three of these KPIs are technical KPIs and 111 are softKPIs. The paper explores the implementation of the framework through eMaintenance, discussing the timeline and general formula for each KPI. Results from this study will be applied by the studied company through eMaintenance.
The second paper proposes a new approach to system availability assessment: a parametric Bayesian approach using Markov Chain Monte Carlo (MCMC), an approach that takes advantages of both analytical and simulation methods. In this approach, Mean Time to Failure (MTTF) and Mean Time to Repair (MTTR) are treated as distributions instead of being βaveragedβ to better reflect reality and compensate for the limitations of simulation data sample size. To demonstrate the approach, the paper considers a case study of a balling drum system in a mining company. In this system, MTTF and MTTR are determined in a Bayesian Weibull model and a Bayesian lognormal model respectively. The results show that the proposed approach can integrate analytical and simulation methods to assess system availability and could be applied to other technical problems in asset management (e.g., other industries, other systems).
The third paper proposes a Bayesian approach to system availability assessment. In this novel approach, 1) MTTF and MTTR are treated as distributions instead of being βaveragedβ to better reflect reality and compensate for the limitations of simulation data sample size, 2) MCMC simulations are applied to take advantage of the analytical and simulation methods, and 3) a threshold is established for Time to Failure (TTF) data and Time to Repair (TTR) data, and new datasets with right-censored data are created to reveal the connections between technical and soft KPIs. To demonstrate the approach, the paper considers a case study of a balling drum system in a mining company. In this system, MTTF and MTTR are determined in a Bayesian Weibull model and a Bayesian lognormal model respectively. By comparing the results with and without considering the threshold for censoring data, we show the threshold can be treated as a monitoring line for continuous improvement in the mining company.
KPI framework for maintenance management through eMaintenance
15
Chapter2TheoreticalFramework
This chapter presents the theoretical framework of this research through a literature review. The literature cited includes conference proceedings, journals, international standards, and other indexed publications.
2.1eMaintenanceandmaintenancedecisionβmaking
Maintenance is defined as a combination of all technical, administrative, and managerial actions during the life cycle of an item intended to retain it in, or restore it to, a state in which it can perform the required function (CEN, 2007). Maintenance is not confined to technical actions alone but includes other activities such as management, support planning, preparation, execution, assessment, and improvement (IEC, 2004).
The emergence of Information Technology (IT) has changed the way businesses are conducted. As in other fields, maintenance has benefited, with eMaintenance emerging in the early 2000s. There are varying definitions of eMaintenance. Tsang defines it as follows: eMaintenance is a maintenance strategy, where tasks are managed electronically by the use of real-time item data obtained through digital technologies, such as mobile devices, remote sensing, condition monitoring, knowledge engineering, telecommunications and internet technologies (Tsang, 2002). He explains eMaintenance should be considered a model that enhances the efficiency of maintenance activities by applying Information and Communications Technology (ICT) to provide information. Koc and Lee (2001) and Parida and Kumar (2004) define eMaintenance as a predictive maintenance system that provides monitoring and predictive prognostic functions, while Muller, Marquez, and Iung (2008) define it as a support to execute a proactive maintenance decision-making process. In the former definition, eMaintenance supports eOperations through remote diagnostics and asset management and through simulation-based optimization and decision-making in a specific organizational eBusiness scenario (Karim, 2008). Another view of eMaintenance is the integration of all necessary ICT-based tools to optimize costs and improve productivity through the use of Web services (Bangemann et al., 2004, 2006). In this technological approach to eMaintenance, Web service technology is used to facilitate the integration of information sources containing maintenance-relevant content. Kajko-Mattsson, Karim and Mirijamdotter (2011) define eMaintenance as maintenance managed and performed via computing and/or a multidisciplinary domain based on maintenance and ICT ensuring the eMaintenance services are aligned with the needs and business objectives of both customers and suppliers during the whole product lifecycle.
eMaintenance facilitates the bi-directional flow of data and information into the decision-making and planning process at all levels (Ucar & Qiu, 2005). The emergence of
Chapter 2 Theoretical Framework
16
eMaintenance has reduced the problem of ineffective information logistics caused by the vast information associated with the maintenance of complex technical industrial systems. It is now much effective to access hidden information in vast amounts of data, stored for other purposes, at different places, in different formats, and generated throughout the entire life cycle of the system thanks to the coming together of information technology and maintenance (Karim, 2008).
eMaintenance has many other benefits, including energy efficiency, sustainability, safety, quality, and reduced costs (Jantunen, Emmanouilidis, Arnaiz, & Gilabert, 2011). It also offers advanced diagnostics and improved productivity (Kour, Aljumaili, Karim, & Tretten, 2019).
eMaintenance offers enhanced maintenance decision-making by answering the following questions:
Are we doing things right? Are we doing the right things? How do we decide the right things?
To answer these questions, maintenance performance measurements (see Section 2.3) are needed.
1. Maintenance Descriptive Analtyics
Whathashappened?
4. Maintenance Prescriptive Analtyics
Whatneedstobedone ?
2. Maintenance Diagnositic Analtyics
Whysomethinghashappened?
3. Maintenance Predictive Analtyics
Whatwillhappeninthefuture ?
MaintenanceAnalytics
Figure 2.1 The constitution phases of Maintenance Analytics (Karim, et al. 2016)
To support maintenance decision-making smoothly and efficiently, Maintenance Analytics (MA) has been proposed based on four interconnected time-lined phases (See Figure 2.1), which aim to facilitate maintenance actions through enhanced understanding of data and information. The MA phases include: 1) Maintenance Descriptive Analytics; 2) Maintenance Diagnostic Analytics; 3) Maintenance Predictive Analytics; and 4) Maintenance Prescriptive analytics. eMaintenance implies a wide range
KPI framework for maintenance management through eMaintenance
17
tools, technologies, and methodologies aimed for maintenance decision-making, including analytics. Hence, eMaintenance can be considered as a concept through which MA can be materialised (Karim, et al., 2016). By applying MA, KPIs can be monitored in a novel way with high efficiency through KPI ontology and taxonomy in an eMaintenance environment. Therefore, the following information is necessary to create maintenance KPIs:
Content: What KPIs do we need? Why are they needed? Data source: Where can we find the necessary information? Timeline: When do we need to measure? General formula: How do we calculate the KPIs?
While a great deal of work has dealt with maintenance KPIs, few studies have discussed the detailed requirements (content, data sources, timeline, and general formulas) for implementing maintenance KPIs through eMaintenance.
2.2Performancemeasurement
Performance measurement is critical to the success of organizations (Bourne, Melnyk, & Bititci, 2018). Those using a balanced or integrated performance measurement system perform better than those that do not (Lingle & Schiemann, 1996) because performance measures provide an important link between strategies and action and thus support the implementation and execution of improvement initiatives (Muchiri, Pintelon, Gelders, & Martin, 2011).
Performance measurement requires the formulation of Key Performance Indicators (KPIs), a set of measures that focus on those aspects of organizational performance that are most critical for current and future success (Parmenter, 2007). KPIs demonstrate how effectively a company is achieving key business objectives. They evaluate the companyβs success in reaching targets and the degree to which areas within the company (e.g., maintenance) achieve their goals.
Many authors have written about performance measurement, including Kaplan and Norton (1992), Neely (1999), Bourne, Mills, Wilcox, Neely, and Platts (2000), Campbell and Reyes-Picknell (2006), Coetzee (1997), Weber and Thomas (2005), Dwight (1995; 1999b), and Tsang (2000).
It is not enough to develop KPIs. The KPIs must be maintained using four fundamental processes: design, plan and build, implement and operate, and refresh. These are shown in Figure 2.2 and described at greater length below.
Chapter 2 Theoretical Framework
18
Figure 2.2 Neelyβs fundamental process of performance measurement
Design: This is concerned with understanding what should be measured and defining how it should be measured, i.e. the metric. To achieve the desired ends and encourage the appropriate behaviour, individual measures require precise and careful design. The first step is to create a framework, taking into consideration the companyβs goals and objective. This framework shows what will be developed, and what will be measured.
Plan and Build: This includes gaining access to the required data, building the measurement system, configuring data manipulation and distribution and overcoming peopleβs political and cultural concerns about performance measurement. This part helps develop the general formulas for the KPIs suggested in the framework.
Implement and Operate: This involves actually managing the measures using the measurement data to understand what is going on in the organization and applying that insight to drive improvements in performance. The most difficult part of performance measurement is managing the data. When data are acted upon, there will be value in measuring. In this stage, the actual development of the KPIs can begin.
Refresh: This is concerned with the measurement system itself, making sure it is refreshed and refined continuously, and the measures remain relevant to the needs of the company. A performance measurement system is a living entity which must evolve and be nurtured over time. This part is very important and should be considered to keep the KPIs relevant.
KPI framework for maintenance management through eMaintenance
19
Using Neelyβs KPI definition guide, 36 questions must be answered to define each KPI, with the questions divided into ten overarching categories. An indicator is considered to be defined when the following categories of questions are answered:
Measurement: 1. What should the measure be called? 2. Does the title explain what the measure is? 3. Is it a title that everyone will understand? 4. Is it clear why the measure is important?
Purpose: 5. Why is the measure being introduced? 6. What is the aim/intention of the measure? 7. What behaviours should the measure encourage?
Relationships: 8. Which other measures does this one closely relate to? 9. What specific strategies or initiatives does it support?
Metric/Formula: 10. How can this dimension of performance be measured? 11. Can the formula be defined in mathematical terms? 12. Is the metric/formula clear? 13. Does the metric/formula explain exactly what data are required? 14. What behaviour is the metric/formula intended to induce? 15. Is there any other behaviour that the metric/formula should induce? 16. Is there any dysfunctional behaviour that might be induced? 17. Is the scale being used appropriately? 18. How accurate will the data generated be? 19. Are the data accurate enough? 20. If an average is used how much data will be lost? 21. Is the loss of βgranularityβ acceptable? 22. Would it be better to measure the spread of performance?
Target level(s): 23. What level of performance is desirable? 24. How long will it take to reach this level of performance? 25. Are interim milestone targets required? 26. How do these target levels of performance compare with competitors? 27. How good is the competition currently? 28. How fast is the competition improving?
Frequency: 29. How often should this measure be made? 30. How often should this measure be reported? 31. Is this frequency sufficient to track the effect of actions taken to improve?
Source of data: 32. Where will the data tracking this measure come from?
Chapter 2 Theoretical Framework
20
Who measures: 33. Who, by name, function or external agency, is actually responsible for
collecting, collating and analysing these data? Who acts on the data (owner):
34. Who, by name or function, is actually responsible for initiating actions and ensuring performance along this dimension improves?
What they do: 35. How exactly will the measure owner use the data? 36. What actions will they take to ensure performance along this dimension
improves?
Although Neelyβs KPI definition guide is detailed, it has drawbacks. For one thing, the method is very time-consuming.
2.3Maintenanceperformancemeasurement
The influence of maintenance on profitability is too high to ignore (Kumar & Ellingson, 2000). With reduced natural resource reserves, e.g. iron ore, oil and gas, and the unstable prices of these resources on the global market, the process industries working with these resources, such as mining companies, must optimise the maintenance process (Kumar & Ellingson, 2000). Because maintenance performs a service function for production, its merits or shortcomings are not always immediately apparent (Muchiri et al., 2011), but it must be measured for companies to remain profitable. This requires the development and use of a suitable set of KPIs.
Some authors have looked specifically at maintenance performance measurement (MPM), including Parida and Chattopadhyay (2007), Kumar, Galar, Parida, StenstrΓΆm, and Berges (2013), and StenstrΓΆm (2014). These authors proposed measuring the performance of maintenance by focusing on the maintenance process or on the maintenance results (Kumar et al., 2013).
Dwight (1999a) suggested a βvalue-based performance measurementβ, a system audit approach to measuring the maintenance systemβs contribution to organizational success. His approach takes into account the impact of maintenance activities on the future value of the organization, with an emphasis on variations in the lag between actions and outcomes.
Tsang (1998) proposed a strategic approach to managing maintenance performance using a balanced scorecard (Kaplan and Norton, 1992; Kaplan and Norton, 1996). However, the success of the balanced scorecard approach depends on how individual companies use it.
LΓΆfsten (2000) advocated the use of aggregated measures like the maintenance productivity index, which measures the ratio of maintenance output to maintenance input. But Muchiri et al. (Muchiri et al., 2011) say LΓΆfstenβs approach gives a very limited
KPI framework for maintenance management through eMaintenance
21
view of maintenance performance, as such it is difficult to quantify different types of maintenance inputs.
Parida and Chattopadhyay (2007) proposed a multi-criteria hierarchical framework for MPM; the framework includes multi-criteria indicators for each level of management, i.e. the strategic, tactical and operational levels. These multi-criteria indicators are categorized as equipment-/process-related (e.g. capacity utilization, OEE, availability, etc.), cost-related (e.g. maintenance cost per unit of production cost), maintenance-task-related (e.g. the ratio between planned and total maintenance tasks), customer and employee satisfaction-related, and health, safety and the environment-related, with indicators proposed for each level of management in each category.
Al-Najjar (2007) designed a model to describe and quantify the impact of maintenance on a businessβs key competitive objectives related to production, quality and cost. The model can be used to assess the cost effectiveness of maintenance investment and provide strategic decision support for different improvement plans.
Muchiri et al. (2011) proposed an MPM system based on the maintenance process and maintenance results. These authors sought to align maintenance objectives with manufacturing and corporate objectives and provide a link between maintenance objectives, maintenance process/efforts and maintenance results. Based on this conceptual framework, they identified performance indicators of the maintenance process and maintenance results for each category. Their conceptual framework provides a generic approach to developing maintenance performance measures with room for customization for individual company needs.
The above proposals are based on both new and existing techniques; some are quantitative and others are qualitative. At this point, there is no integrated approach to measuring the performance of all components of maintenance. In addition, few studies consider the implementation of a KPI framework through eMaintenance; few discuss data sources or databases, timelines, or general formulas for specified KPIs.
2.4KPIassessment
To develop novel approaches to assessing both technical and soft KPIs, this study selected system availability as an example for illustration. This section focuses on system availability assessment and quantitative approaches that can be used to assess and predict soft KPIs.
2.4.1Systemavailabilityassessment
Availability represents the proportion of a systemβs uptime out of the total time in service and is one of the most critical aspects of performance evaluation. Availability is commonly measured as Mean Time to Failure (MTTF) and Mean Time to Repair (MTTR). However, those βmeanβ values are normally βaveragedβ; thus, some useful information
Chapter 2 Theoretical Framework
22
(e.g., trends, system complexity) may be neglected, and some problems may even be hidden.
Assessment of system availability has been studied from the design stage to the operational stage in various system configurations (e.g., in series, parallel, k-out-of-n, stand-by, multi-state, or mixed architectures). Approaches to assessing system availability mainly use either analytic or simulation techniques.
In general, analytic techniques represent the system using direct mathematical solutions from applied probability theory to make statements on various performance measures, such as the steady-state availability or the interval availability (Dekker & Groenendijk, 1995; Ocnasu, 2007). Researchers tend to use Markov models to assess dynamic availability or semi-Markov models using Laplace transforms to determine average performance measures (Dekker & Groenendijk, 1995; Faghih-Roohi, et al., 2014). However, such approaches have been criticised as too restrictive to tackle practical problems; they assume constant failure and repair rates which is not likely to be the case in the real world (Raje, et al., 2000; Marquez, et al., 2005). Furthermore, the time dependent availability obtained by a Markovian assumption is not valid for non-Markovian processes (Raje, et al., 2000).
Simulation techniques estimate availability by simulating the actual process and random behaviour of the system. The advantage is that non-Markov failures and repair processes can be modelled easily (Raje, et al., 2000). Researchers are currently working on developing Monte Carlo techniques to model the behaviour of complex systems under realistic time-dependent operational conditions (Marquez, et al., 2005; Marquez & Iung, 2007; Yasseri & Bahai, 2018) or to model multi-state systems with operational dependencies (Zio, et al., 2007). Although simulation is more flexible, it is computationally expensive.
Traditionally, Bayesian approaches have been used to assess system availability as they can solve the problem of complicated system state changes and computationally expensive simulation data; however, their development and application have been stalled by the strict assumptions on prior forms and by computational difficulties. Research is more concerned with the priorβs selection or the posteriorβs computation than the reality (Brender, 1968; Kuo, 1985; Sharma & Bhutani, 1993; Khan & Islam, 2012). The recent proliferation of Markov Chain Monte Carlo (MCMC) simulation techniques has led to the use of the Bayesian inference in a wide variety of fields. Because of MCMCβs high dimensional numerical integral calculation (Lin, 2014), the selection of prior information and descriptions of reliability/maintainability can be more flexible and more realistic.
2.4.2Somequantitativeapproaches
This section introduces some quantitative approaches used in the research. Bayesian survival analysis with MCMC is proposed as a novel approach to assessing system
KPI framework for maintenance management through eMaintenance
23
availability; time series analysis, Crostonβs method, and the bootstrap method are proposed as methods to assess and predict soft KPIs.
2.4.2.1BayesiansurvivalanalysiswithMCMC
Bayesian theory comes from βAn essay towards solving a problem in the doctrine of chancesβ by Bayes (1958). In this paper, Bayes proposed that based on observed data set π·, any unknown parameter π can be viewed as a random parameter. To apply a probability distribution π π to describe π, the probability distribution must be for prior information which exists before sampling, or prior distribution. Given the sample likelihood function πΏ π|π· and the prior distribution π π , we can get the posterior distribution for π as
π π|π·πΏ π|π· π π
πΏ π|π· π π ππ 2.4.1
Important discussions on Bayesian theory include Box and Tiao (1992), Press (1991), Gelman, et al. (2004), etc.
Survival analysis is a method used to study time-to-event data. In survival analysis, the survival function π π‘ is actually the reliability function π π‘ , which can be defined as
π π‘ π π‘ π π π‘ 1 π π π‘ 2.4.2
where π 0 1 and π β 0 . Here, πΉ π‘ is the distribution function of π . The relationships between the hazard function β π‘ and reliability function π π‘ is
β π‘lim
β βπ π‘ π π‘ βπ‘|π π‘
βπ‘πππ‘
log π π‘ 2.4.3
In practice, lifetime data are usually incomplete, and only a portion of the individual lifetimes of assets are known. Right-censored data are often called Type I censoring in the literature; the corresponding likelihood construction problem has been extensively studied. Suppose there are π individuals whose lifetimes and censoring times are independent. The πth individual has lifetime π and censoring time πΏ . The π s are assumed to have probability density function π π‘ and reliability function π π‘ . The exact lifetime π of an individual will be observed only if π πΏ . The lifetime data involving right censoring can be conveniently represented by π pairs of random variables π‘ , π£ , where π‘ min π , πΏ and π£ 1 if π πΏ and π£ 0if π πΏ . That is,
Chapter 2 Theoretical Framework
24
π£ indicates whether the lifetime π is censored or not. The likelihood function is deduced as
πΏ π‘ π π‘ π π‘ 2.4.4
Related references include Lawless (1982), Hougaard (2000), Cox and Oakes (1984) and Therneau and Grambsch (2000).
The recent proliferation of Markov Chain Monte Carlo (MCMC) approaches has led to the use of the Bayesian inference in a wide variety of fields. MCMC is essentially Monte Carlo integration using Markov chains (Lin, 2014; Lin, 2016). Monte Carlo integration draws samples from the required distribution and then forms sample averages to approximate expectations. MCMC draws out these samples by running a cleverly constructed Markov chain for a long time. There are many ways of constructing these chains.
The Gibbs sampler is one of the best known MCMC sampling algorithms in the Bayesian computational literature. It adopts the thinking of βdivide and conquerβ: i.e., when a set of parameters must be evaluated, the other parameters are assumed to be fixed and known. Let ΞΈ be an i-dimensional vector of parameters, and let f ΞΈ denote the marginal distribution for the j th parameter. The basic scheme of the Gibbs sampler for sampling from p ΞΈ is given as follows:
Step 1. Choose an arbitrary starting point π π , β¦ , π ;
Step 2. Generate π from the conditional distribution π π |π , β¦ , π , and
generate π from the conditional distribution π π |π , π , β¦ , π ;
Step 3. Generate π from π π |π , β¦ , π , π β¦ , π ;
Step 4. Generate π from π π |π , π , β¦ , π ; the one-step transition
from π to π π , β¦ , π has been completed, where π is a one-time accomplishment of a Markov chain.
Step 5. Go to Step2.
After t iterationsοΌΞΈ ΞΈ , β¦ , ΞΈ can be obtained. Each component of ΞΈ can also be obtained. Starting from different ΞΈ , as t β β, the marginal distribution of ΞΈ can be viewed as a stationary distribution based on the theory of the ergodic average. Then, the chain is seen as converging, and the sampling points are seen as observations of the sample.
Bayesian survival analysis has been developed for small samples to make the most of the priorsβ information in application, especially to deal with incomplete (truncated or censored) data. It has received much recent attention with advances in computational and modelling techniques. When regression models can consider different environmental factors, the simulations for parametersβ posterior distribution will be easier, and the theory of Bayesian survival analysis better developed.
KPI framework for maintenance management through eMaintenance
25
2.4.2.2Timeseriesanalysisforcontinuousdemandforecasting
Continuous demand forecasting can be modelled using time series analysis. A time series is a set of observations recorded at a specific time; it is useful for serially correlated data. Time series forecasting is used in statistics, finance, econometrics, weather forecasting, earthquake prediction, etc. A continuous time series is obtained when observations are made continuously over a certain time interval. One popular continuous forecasting method is the Autoregressive Moving Average (ARMA) model, also referred to as the Box-Jenkins model (Box & Jenkins, 1968), two authors who were central to its development.
An ARMA π, π model comprises two parts;
1. An AR π process:
π π π π π 2.4.5
where π is a constant, π are parameters of the model and π is random noise.
2. An MA π process:
π π π π π 2.4.6
where π is a constant, and π are parameters.
These two combine to give the ARMA π, π model:
π π π π π π π 2.4.7
Thus, the ARMA π, π model allows the modelling of points in a time series dependent on the previous π points (auto-regressive) and on the previous π residuals (moving-average).
To model an ARMA π, π model, the time series data must generally be stationary; i.e. they must have a constant mean, constant variance and constant covariance, irrespective of time. This is not always the case in time series data.
An extended version of the ARMA π, π method, the ARIMA π, π, π method, exists for such data. ARIMA stands for Autoregressive Integrated Moving Average. The π stands for differencing and is a transformation technique applied to time-series data to make
Chapter 2 Theoretical Framework
26
them stationary. Differencing is mathematically shown as π¦ , π¦ π¦ ; differencing removes the changes in the level of a time series, thus eliminating trend and seasonality, consequently stabilizing the mean of the time series.
2.4.2.3Crostonβsmethodforintermittentdemandforecasting
Intermittent demand time series refers to items that are requested infrequently, resulting in sporadic demand (Kourentzes, 2014), thus showing periods of zero demand. A popular approach to forecasting such demand is Crostonβs method and its variants. Crostonβs method is an ad hoc method with no properly formulated underlying stochastic model, and, as such, it is inconsistent with the properties of intermittent demand data (Shenstone & Hyndman, 2005). Yet its forecasts and prediction intervals based on its underlying models are very useful when predicting intermittent demand (Shenstone & Hyndman, 2005).
Crostonβs method was proposed by Croston in 1972. The method estimates demand probability using time interval series and demand series separately, thus making it more intuitive and accurate. It is calculated as below:
If π is the estimate of mean non-zero demand series for time π‘, π is the estimate of mean interval size between non-zero demands, π is the actual demand observed at time π‘, π is the current number of consecutive zero-demand periods, and
π denotes an estimate of mean demand size considering zero demands, then
if π 0, then π πΌπ 1 πΌ ππ πΌπ 1 πΌ π
π π πβ 2.4.8
Otherwise,
if π 0, then π ππ ππ π
2.4.9
Even though Crostonβs method has been demonstrated to give good, useful and robust forecasts in both empirical experiments and practical use, it is biased and lacks independent smoothing of parameters for demand size and interval size; it assumes demand size and demand interval are independent, and there is no way to deal with product obsolescence.
As a result of Crostonβs limitations, variants such as the Syntetos-Boylan Approximation (SBA) method, Shale-Boylan-Johnston (SBJ) method and the Teunter, Syntetos and Babai (TSB) method have been proposed. Syntetos and Boylan (2001)
KPI framework for maintenance management through eMaintenance
27
claimed to have removed biases associated with the original Croston method, thus improving its accuracy. Shale, Boylan and Johnston (2006) considered a Poisson process for the arrival of orders. Teunter, Syntetos and Babai (2011) updated the probability of demand continuously; this method is useful for products nearing the end of their life cycle.
2.4.2.4Bootstrapmethodforslowmovingdemandforecasting
Slow moving demand time series involve a statistical technique called bootstrapping proposed by Willemain, Smart and Schwartz (2004). This method involves random sampling with replacement on previous observations of non-zero demand to forecast demand over some lead-time i.e. the interval between replenishment ordering and arrival of the order. This prediction method is particularly useful when the sample size is relatively small, and difficult to accurately predict based on an assumed distribution of the data.
Bootstrapping generates tens of thousands of demand groups over the lead time period based on the originally small sample and predicts the distribution and average demand of the original time series based on the distribution of the new data generated. The prediction results include both the confidence level and the average demand within the period, so it is a better risk prediction method.
The advantage of bootstrapping is that it does not assume the distribution of samples based on theoretical assumptions. Instead, it uses a computer to perform simulation calculations based on empirical data to obtain large sample data to simulate the previous small sample distribution. The size of the sample generated by the computer is determined by the specific project and can be adjusted according to the complexity of the algorithm and the efficiency of the execution.
2.5Summaryofresearchframework
Theories on maintenance performance measurement have some gaps. First, no KPI framework considers both technical and soft KPIs (see RQ1); second, few studies have focused on implementing KPI measurement through eMaintenance; they do not discuss data sources or databases, timelines, or general formulas for specified KPIs (see RQ2).
Theories on performance measurement provide the basis of this research for developing a KPI framework. Neelyβs fundamental process of performance measurement supports a continuous improvement process for the developed KPIs from design, to plan and build, implementation and operation, and refreshment. Although Neelyβs KPI guide is detailed, it has drawbacks. For one thing, the method is very time-consuming (see RQ4).
Chapter 2 Theoretical Framework
28
There are also gaps in KPI assessment (see RQ3). The current analytical (e.g., Markov/semi-Markov) or simulation approaches (e.g., Monte Carlo simulation-based) cannot handle complicated state changes or are computationally expensive. There is a need to develop novel approaches (see RQ3.1). In addition, few researchers have revealed the connections between technical and soft KPIs (see RQ3.2). For those soft KPIs for which the distribution of data collected from eMaintenance systems (e.g., work orders) is not easily determined, we could apply time series analysis if the data are βfast movingβ, the Croston method if the data are βintermittentβ or the bootstrap method if the data are βslow movingβ (see RQ3.3).
Figure 2.2 Theoretical framework in this research
Connections of research publications and RQs in the theoretical framework could be found in Figure 2.2.
KPI framework for maintenance management through eMaintenance
29
Chapter3ResearchMethodology
This chapter presents the research methodology, including research design, data collection, literature review, and data analysis.
3.1Researchdesign
This section presents the design of this research. As shown in Figure 3.1, the research can be divided into three stages.
The motivation for the research originated in the project βKey Performance Indicators (KPI) for control and management of maintenance process through eMaintenance (in Swedish: Nyckeltal fΓΆr styrning och uppfΓΆljning av underhΓ₯llsverksamhet m h aeUnderhΓ₯ll)β, initiated and supported financially by LKAB. More specifically, LKAB is cooperating with LTUβs eMaintenance Lab to develop an integrated KPI framework to control and monitor its maintenance process to achieve its overall organizational goals. This new KPI framework is expected to comprise two parts: technical KPIs (linked to machines) and business KPIs (linked to workflow); the latter ones are also called soft KPIs based on business strategies of the mining company. LKAB and the eMaintenance Lab at LTU jointly conducted an exploratory study to lay the foundations for further study.
The first stage of the project included a literature review, interviews with infrastructure managers, maintenance engineers at LKAB, researchers for KPI development in EU projects, etc. The interviews, combined with the literature review, revealed the research gaps in LKABβs current KPI framework development, implementation, assessment, and optimization and allowed the formulation of a problem statement. This, in turn guided the formulation of the research purpose, objectives and four research questions: RQ1, RQ2, RQ3 and RQ4. RQ3 includes three sub-questions. The second stage of the project, exploratory research, examined technical and βsoftβ KPIs and the connections between them.
In the third stage, the work drew on both descriptive and explanatory research to construct an integrated KPI framework for maintenance management in an eMaintenance environment. The framework includes asset operation management, maintenance process management and maintenance resources management. In all, 134 technical and soft KPIs are proposed to measure maintenance performance and streamline maintenance processes: asset operation management has 23 technical KPIs; maintenance process management has 85 soft KPIs; maintenance resources management has 26 soft KPIs. The novel framework was applied and validated in case studies in the mining company. The case studies indicate that the integrated KPI
Chapter 3 Research Methodology
30
framework will allow the overall business goals to be reached and the system to be optimized continuously.
Generally speaking, the first stage revealed the research gaps, the second stage analysed them, and the third stage resolved the research problems and filled the research gaps.
Figure3.1Designoftheresearch
Integrated KPI framework for maintenance management through eMaintenance: development, Implementation, assessment, and optimization
Research Background
Project ideas motivated by LKAB and
eMaintenance LabLiterature Review Interview
Performance measurement
KPI implementation
KPI frameworkKPI assessment
and Optimization
RQ 1: What is the KPI framework?
RQ 2: How can it be implemented?
RQ 3: How can it be assessed?
RQ 4: How can it be improved
continuously?
Integrated KPI framework
Implementation through eMaintenance
New assessment approaches
Optimization approaches
New framework
Asset operation management
Maintenance process management
Maintenance resources management
Des
crip
tive
and
exp
lana
ory
rese
arch
Expl
orat
ory
rese
archA
nswer research questions
Fill research gaps
Ove
rall
Bus
ines
s go
alContinuous
Improvem
ent
Case studies
Research Objectives and questions
KPI framework for maintenance management through eMaintenance
31
3.2Datacollection
This section explains data collection from interviews, documents received from the mining company, and other data sources.
3.2.1Interviews
Three groups of people were interviewed: infrastructure managers and maintenance engineers at LKAB, and researchers working on KPI development in other industries. Interviews were conducted throughout the research.
At the start of the research, the interviews took advantage of the experience of maintenance personnel to identify the research gaps and formulate the research purpose, objectives and questions.
The purpose for later interviews was to consult experts on the research approach, discussion, conclusions and further research work.
3.2.2Documentsfromtheminingcompany
Internal LKAB documents were consulted to understand the companyβs overall business goals, current KPI structure, maintenance process, KPI development plan, etc. These documents formed the foundation of the research. Those without confidentiality problems are mentioned in Chapter 1, Chapter 5 and appended publications.
3.2.3Datasources:operationandmaintenancedata
Historical data were collected from LKAB. Status monitoring data were gathered from Plantperformance/IP21. Historical data on maintenance were collected from Movex, and economic data were collected from total report operation and maintenance (TDU).
Time to Failure (TTF) data and Time to Repair (TTR) data for paper B and paper C were collected for five balling drums from January 2013 to December 2018.
3.3Literaturereview
The literature review drew on scientific publications databases, such as Scopus, Web of Science, Google Scholar, etc. Various types of reference were reviewed, including conference and journal papers, monographs, theses, standards and technical reports. Secondary references were reviewed in some cases. A summary of the results of these literature reviews is given in Chapter 2, βTheoretical frameworkβ, and is applied in Chapter 5 βResults and discussionsβ. More details can be found in the appended papers.
Chapter 3 Research Methodology
32
3.4DataAnalysis
After data collection, the next step was to analyse the data to produce information, knowledge and insights. During this step, data were categorized, cleaned, transformed, inspected and modelled.
3.4.1DataanalysisinPaperB
Paper B describes a case study illustrating system availability assessment using a parametric Bayesian approach. The main steps of data analysis in Paper B follow the procedure shown in Table 3.1.
Table3.1StepsinthesystemavailabilityassessmentofPaperB
Steps Name Purpose Outputsinthiscase
1 Configuration definition
System configuration and dependencies determined to calculate system availability.
Five balling drum system parallel and independent.
2 Data collection Reliability and maintenance data (and information) collected.
1774 records for failure and repair data of the five balling drums collected from 2013 to 2018.
3 Data preparation
Data cleaned and outliers removed as needed.
Null values removed and abnormal data checked.
4 Preliminary Analysis
Pre-studies for TTF and TTR data performed to decide the baseline distributions.
MTTF fitted a Weibull distribution; MTTR fitted a lognormal distribution.
5 Parametric Bayesian model building
Prior distribution defined, and analytic models developed.
Bayesian Weibull model for MTTF with gamma priors and Bayesian lognormal model with gamma and normal priors constructed.
6 MCMC simulation
Burn-in defined and MCMC simulation implemented; convergence diagnostics and Monte Carlo error checked to confirm the effectiveness of the results.
Burn-in of 1000 samples used with an additional 10,000 Gibbs samples for each Markov chain.
7 Results and analysis
Results, calculation and discussion.
Results for parameters of interest in system availability assessment.
Paper B is motivated by a balling drum system in the mining industry. The case study mine has five balling drums. All five receive their feed for production in the same manner. Each balling drum is expected to produce the same amount of pellets at its maximum. According to the working mechanism and an i. i. d test, they are considered independent; if one breaks down, it does not affect the rest, except that total production
KPI framework for maintenance management through eMaintenance
33
will be reduced. One assumption is made here that the system will fail only if all subsystems fail; therefore, it is treated as a parallel system.
There are 1782 records. In the first step, the null values are removed, and the data are reduced to 1774 records.
The next step reveals there are different reasons for the TTF and TTR of individual balling drums. It is noticed that, for TTR data, if 150 shutdowns are considered normal (denoted as a threshold; see Figure 3.2), then those exceeding 150 should be treated as abnormal and investigated using Root Cause Analysis (RCA).
When we check the work order types of such kinds of abnormal data, we discover most are caused by βpreventive maintenanceβ and may reflect a lack of maintenance resources. To simplify the study, we assume all maintenance resources are sufficient for βpreventive maintenanceβ; thus, although the abnormal data might be caused by a shortage of spare parts or skilled personnel, this possibility is not examined in the paper.
Figure3.2ExampleofTTRdataforballingdrum1
To determine the baseline distribution of Time to Failure (TTF) and Time to Repair (TTR), we conduct a preliminary study of failure data and repair data using traditional analysis. In this preliminary study, several distributions are considered: exponential distribution, Weibull distribution, normal distribution, log-logistic distribution, lognormal distribution, and extreme value distribution. Table 3.2 lists the results.
Based on the results, the Weibull distribution and lognormal distribution are selected for the TTF and TTR for balling drums 1 to 5; these are applied to the parametric Bayesian models in the study. The main procedure of Bayesian analysis with MCMC follows Figure 3.3 (Lin, 2014).
Chapter 3 Research Methodology
34
Table3.2Preliminarystudyoffailuredataandrepairdata
BallingdrumTTFfitness TTRfitness
1st 2nd 3rd 1st 2nd 3rd 1 Weibull Log-logistic Lognormal Lognormal Weibull Logistic 2 Weibull Log-logistic Lognormal Lognormal Weibull Logistic 3 Weibull Log-logistic Lognormal Lognormal Weibull Logistic 4 Weibull Log-logistic Lognormal Lognormal Weibull Logistic 5 Weibull Log-logistic Lognormal Lognormal Weibull Logistic
Figure3.3AProcedureforBayesianReliabilityInferenceviaMCMC
According to the results of paper B, the distribution for TTF and TTR can be achieved separately for balling drums 1 to 5. The traditional method of assessing availability is
π΄ππππΉ
ππππΉ ππππ
KPI framework for maintenance management through eMaintenance
35
However, the proposed approach extends the method to
π΄πΈ π πππΉ
πΈ π πππΉ πΈ π πππ
πΈ π π‘ |πΌ, πΎπΈ π π‘ |πΌ, πΎ πΈ π π‘ |π, π .
The above equation shows the flexibility of assessing availability according to reality. For one thing, the parametric Bayesian models using MCMC make the calculation of posteriors more feasible.
3.4.2DataanalysisinPaperC
The main difference between the procedure in paper B and paper C is the latterβs use of a threshold to censor the data.
In paper C, as in paper B, the proposed Bayesian approach to system availability has seven steps divided into three stages (see Table 3.3). In Stage I, we perform pre-analysis; in Stage II, we create the analytic models (Bayesian) and simulation models (MCMC); in Stage III, we assess system availability.
The seven steps follow a βPDCAβ cycle; those in Stage I can be treated as the Plan stage, Stage II as the Do and Check stage, and Stage III as the Action stage. The outputs from Stage III could become input for Stage I for the next calculation period, so the results can be continuously improved.
Table3.3Generalprocedure
Stages Steps Name Description
I
1 Configuration determination
Determine dependencies among units and system configuration.
2 Data collection Collect prior information and event data, including reliability and maintenance data.
3 Data preparation
Clean data and remove outliers as needed. Set up a threshold for censored data.
4 Preliminary analysis
Determine the distribution of prior information, TTF, and TTR for the Bayesian analytics in step 5.
II
5 Bayesian analytic modelling
According to step 3 and step 4, determine the likelihood function and Bayesian analytic models.
6 MCMC simulation
Define burn-in defined and implement MCMC simulation; perform convergence diagnostics and check Monte Carlo error to confirm the effectiveness of the results. If not passed, go back to step 4 and 5; if passed, go to step 7.
III 7 Assessment
According to the simulation results for Bayesian analytic models and system configuration, determine distributions of TTF and TTR and assess system availability. Assessment could start with the prior information collection in step 2 for the next calculation period.
Chapter 3 Research Methodology
36
In paper C, we look for the normal and abnormal values for the TTF and TTR of individual balling drums. If 150 shutdowns in Figure 3.2 are considered normal, for example, then those exceeding 150 are abnormal, and 150 is denoted as a threshold, as shown in Figure 3.2. The work orders show most of these abnormal shutdowns are caused by βpreventive maintenanceβ and may simply reflect a lack of maintenance resources. To simplify the study, we assume that not all maintenance resources are sufficient for βpreventive maintenanceβ; thus, the abnormal data may reflect a shortage of spare parts or skilled personnel.
To establish a more reasonable TTR threshold than the 150 shutdowns, we perform a Pareto analysis for all balling drums. The results appear in Figure 3.4. According to the figure, if the threshold is set up according to the β80-20β rule, the data can be censored at six hours. This explains almost 80% of the data. Therefore, we create a new dataset with TTR censored at six hours.
Figure3.4ParetoanalysisforTTRoffiveballingdrums
In addition, we make the following assumptions:
1. Abnormal TTR values exceeding six hours could be improved by implementing maintenance improvements, including RCA, maintenance resource improvement, etc. The goal is to reduce the TTR values exceeding six hours. However, we donβt know how much this reduction can be. Therefore, those values are considered right censored at six;
2. The preventive maintenance plan is not changed. Thus, if one TTR is treated as censored, then in the corresponding maintenance interval, the Time between Failure (TBF), which equals to TTF plus TTR, will not change significantly, and the TTF could be longer than in the collected data. However, we donβt know how much longer the TTF could be. Therefore, TTF data can also be treated as right
KPI framework for maintenance management through eMaintenance
37
censored. The difference with censored TTR data is that the corresponding TTF data are treated as right-censored at the original value instead of a new value (see Figure 3.5).
Figure3.5Datacensoredunderassumptions
We use Figure 3.5 to illustrate assumption 2. TBF equals to the time between t and t . TTR =t - t might be larger than six but it is right censored at six. Then, the original TTR is denoted as six with a right-censored indicator. Since TBF=t - t will not change, the corresponding TTFβ= t t will be longer than TTF. However, according to assumption 2, we donβt know how much longer; therefore, TTFβ is denoted as right-censored data with an original value equal to t - t .
After this step, the censored TTF and TTR data represent a total of 20% of all data.
To determine the baseline distribution of TTR and TTF, we conduct a preliminary study of failure data and repair data using traditional analysis. We consider the following distributions: exponential distribution, Weibull distribution, normal distribution, log-logistic distribution, lognormal distribution, and extreme value distribution. Table 3.4 lists the results, including the goodness-of-fit using Anderson-Darling (AD) statistics.
Table3.4Preliminarystudiesoffailuredataandrepairdata
Ballingdrum
TTFfitness TTRfitness1st AD 2nd AD 1st AD 2nd AD
1 Weibull 1.976 Lognormal 11.276 Lognormal 10.068 Weibull 14.607 2 Weibull 1.796 Lognormal 8.274 Lognormal 11.144 Weibull 14.302 3 Weibull 2.115 Lognormal 10.499 Lognormal 8.698 Weibull 14.332 4 Weibull 1.196 Lognormal 6.366 Lognormal 9.245 Weibull 13.106 5 Weibull 2.148 Lognormal 14.416 Lognormal 7.533 Weibull 11.933
Based on the results, we select the Weibull distribution for the TTF and the lognormal distribution for the TTR and apply these to their respective parametric Bayesian models with censored data, as explained in paper C. The main procedure of Bayesian analysis with MCMC also follows Figure 3.3 (Lin, 2014).
Chapter 3 Research Methodology
38
Paper C propose a Bayesian Weibull model for TTF and a Bayesian lognormal model for TTR with considering right-censored data, and explain how to use an MCMC computational scheme to obtain the posterior distributions with or without considering right-censored data.
According to the results of paper C, the distribution for TTF and TTR can be achieved separately for balling drums 1 to 5. The proposed approach extends the method of assessing availability to
π΄πΈ π πππΉ
πΈ π πππΉ πΈ π πππ
πΈ π π‘ |πΌ, πΎπΈ π π‘ |πΌ, πΎ πΈ π π‘ |π, π .
The above equation shows the flexibility of assessing availability according to reality. And similar to what is shown in Paper B, the parametric Bayesian models using MCMC make the calculation of posteriors more feasible.
As discussed above, system availability can be computed via the TTF and TTR, but we cannot obtain a closed-form distribution of system availability. Therefore, in paper C we use an empirical distribution instead of an analytical one. We generate 10,000 samples from the distributions of TTF and TTF and calculate the associated availability. We use the Kaplan-Meier estimate as the empirical c. d. f. .
3.5Reliabilityandvalidityoftheresearch
Research must be both valid and reliable. Validity refers to studying the right things, while reliability refers to conducting a study in the right way. Validity allows the researcher to measure what was designed to be measured (Karim, 2008), while reliability ensures consistency and repeatability of research procedures, such that the same findings and conclusions are achieved if the same procedure is followed by another researcher (Yin, 2014).
This research achieved validity by using multiple data sources (interviews, workshops, observations and documents) and establishing a chain of evidence. In addition to this use of documentation, Paper A achieved validity by drawing on a case study in the mining industry.
Papers B and C compared the Monte Carlo errors (MC errors) with the Standard Deviation (SD). Note that a MC error less than 5% of SD is considered acceptable and valid, and both papers achieved this; see Table 5.3.1, Table 5.3.2, Table 5.3.4, and Table 5.3.5. Other diagnostics were performed to ascertain the validity of the results, including checking the convergence of the Markov chains. For instance, as Table 5.3.1 shows, the convergence of the Markov chains (i.e., tree chains) of the πΌ and πΎ parameters in the Bayesian Weibull model of the TTF of the first balling drum could be monitored using the trend of the time series history of the data (see Figure 3.6) and the dynamic trace of the three chains (see Figure 3.7). The convergence of the chains could also be checked
KPI framework for maintenance management through eMaintenance
39
using Gelman-Rubin-Brooks (GRB) statistics (see Figure 3.8). Details of the methods are discussed elsewhere by Lin (2014; 2016).
Reliability is achieved by showing the steps used to analyse the data (see Table 3.1, Table 3.3, and Table 5.3.12) and by showing the research findings in the tables and figures (Chapter 5). However, some of the data used in this research are confidential and classified for reasons of organizational security, thus limiting accessibility and repeatability.
πΌ
πΎ
Figure 3.6 History of three chains
πΌ πΎ
Figure 3.7 Dynamic trace of three chains
Chapter 3 Research Methodology
40
πΌ πΎ
Figure 3.8 BGR diagnostic Dynamic trace of three chains
3.6Inductive,deductiveandabductivereasoning
Deductive reasoning, also called deductive logic, is the process of reasoning from one or more general statements on what is known to reach a logically certain conclusion. Inductive reasoning, also called induction or bottom-up logic, constructs or evaluates general propositions derived from specific examples. Both have shortcomings. A weakness of induction is that a general rule is developed from a limited number of observations; a weakness of deduction is that it establishes a rule, instead of explaining it (Peter, 2005).
Abductive reasoning, also called abduction, is used in many case studies. With this approach, a single case is set within an overarching hypothetical pattern. The interpretation is corroborated with new observations. Consequently, abduction may be considered a combination of induction and deduction. During the research process, the empirical application is developed, and the theory adjusted (Peter, 2005).
This research is founded on a common interest among industry and academia in exploring problems that are important in practice but described in an unsatisfactory manner in the literature. Hence, the research could have a deductive or an inductive approach. While the project from which the research originates is based on industrial interest, however, the literature must be studied to attain a deeper understanding. Therefore, an approach similar to abduction is more appropriate.
The iterative abductive approach of this research combines theory and practice; thus, it contributes to the literature both theoretically and empirically.
KPI framework for maintenance management through eMaintenance
41
Chapter4
Summaryoftheappendedpublications
This chapter summarizes the appended papers, giving their title, purpose and abstract. The links between the research questions (RQs) and the appended papers appear in Chapter 1.
4.1PaperA
Title: Development and implementation of a KPI framework for maintenance management in a mining company
Purpose: The purpose of this study is to propose a KPI framework for the mining company and propose its implementation in an eMaintenance environment.
This paper answers RQ 1 (What is a KPI framework for maintenance management?) and RQ2 (How can the developed KPI framework be implemented through eMaintenance?).
Abstract: Performance measurement is critical if organizations want to thrive. The motivation for the research originated from the project βKey Performance Indicators (KPI) for control and management of maintenance process through eMaintenanceβ, initiated and financed by a mining company in Sweden. The main purpose is to develop an integrated KPI framework for the studied mining companyβs maintenance and its implementation through eMaintenance. The proposed KPI framework has 134 KPIs divided into technical and soft KPIs as follows: asset operation management has 23 technical KPIs, maintenance process management has 85 soft KPIs and maintenance resources management has 26 soft KPIs. Its implementation is discussed, and timelines, definitions and general formulas are given for each specified KPI. Results from this study will be applied to the studied company and supply the guidance of implementing those KPIs through eMaintenance.
4.2PaperB
Title: System availability assessment using a parametric Bayesian approach - A case study of balling drums
Purpose:The purpose of this study is to propose a new approach to system availability assessment: it proposes a parametric Bayesian approach with MCMC, with a focus on the operational stage, using both analytical and simulation methods. MTTF and MTTR are treated as distributions instead of being βaveragedβ by point estimation, and this is
Chapter 4 Summary of the appended publications
42
closer to reality. The study also addresses the limitations of simulation data sample size by using MCMC techniques.
This paper answers RQ 3 (How can the KPIs be assessed using novel approaches?), and more specifically, RQ3.1 (How can technical KPIs be assessed using a novel approach?).
Abstract: Assessment of system availability usually uses either an analytical (e.g., Markov/semi-Markov) or a simulation approach (e.g., Monte Carlo simulation-based). However, the former cannot handle complicated state changes, and the latter is computationally expensive. Traditional Bayesian approaches may solve these problems; however, because of their computational difficulties, they are not widely applied. The recent proliferation of Markov Chain Monte Carlo (MCMC) approaches has led to the use of the Bayesian inference in a wide variety of fields. This study proposes a new approach to system availability assessment: a parametric Bayesian approach using MCMC, an approach that takes advantage of both analytical and simulation methods. In this approach, Mean Time to Failure (MTTF) and Mean Time to Repair (MTTR) are treated as distributions instead of being βaveragedβ to better reflect reality and compensate for the limitations of simulation data sample size. To demonstrate the approach, the paper considers a case study of a balling drum system in a mining company. In this system, MTTF and MTTR are determined in a Bayesian Weibull model and a Bayesian lognormal model respectively. The results show that the proposed approach can integrate analytical and simulation methods to assess system availability and could be applied to other technical problems in asset management (e.g., other industries, other systems).
4.3PaperC
Title:A novel Bayesian approach to system availability assessment using a threshold to censor data - A case study of balling drums in a mining company
Purpose:The purpose of this study is to propose a novel system availability assessment approach in the operational stage. The approach will:
Integrate analytical and simulation methods for system availability assessment and have the potential to be applied to other technical problems in asset management (e.g., other industries, other systems);
Reveal the connections between technical and βsoftβ KPI; Establish a threshold to censor data; the threshold can become a monitoring line
for continuous improvement in the mining company.
This paper answers RQ 3 (How can the KPIs be assessed using novel approaches?), and more specifically, RQ3.2 (How can technical and soft KPIs be assessed and improved together using a novel approach?).
Abstract: Assessment of system availability has been studied from the design stage to the operational stage in various system configurations using either analytic or
KPI framework for maintenance management through eMaintenance
43
simulation techniques. However, the former cannot handle complicated state changes and the latter is computationally expensive. This study proposes a Bayesian approach to system availability. In this approach: 1) Mean Time to Failure (MTTF) and Mean Time to Repair (MTTR) are treated as distributions instead of being βaveragedβ to better reflect reality and compensate for the limitations of simulation data sample size; 2) Markov Chain Monte Carlo (MCMC) simulations are applied to take advantage of both analytical and simulation methods; 3) a threshold is established for Time to Failure (TTF) data and Time to Repair (TTR) data, and new datasets with right-censored data are created to reveal the connections between technical and soft KPIs. To demonstrate the approach, the paper considers a case study of a balling drum system in a mining company. In this system, MTTF and MTTR are determined in a Bayesian Weibull model and a Bayesian lognormal model respectively. Comparing the results with and without considering the threshold for censoring data, we show the threshold can be treated as a monitoring line for continuous improvement in the mining company.
Chapter 4 Summary of the appended publications
44
KPI framework for maintenance management through eMaintenance
45
Chapter5ResultsandDiscussion
This chapter discusses the research findings for each research question (RQ).
5.1 ResultsanddiscussionrelatedtoRQ1
RQ1: What is a KPI framework for maintenance management?
The first research question is answered by developing a new framework for maintenance management in Paper A.
In all, there are 134 KPIs in this framework. Asset operation management has 23 technical KPIs, Maintenance process management has 85 soft KPIs, and maintenance resources management has 26 soft KPIs.
5.1.1 KPIframework
The proposed KPI framework makes use of four hierarchical levels. The first level, the asset management system, is the highest level in the framework and encapsulates the second, third and fourth levels.
The second level consists of three broad categories: asset operation management, maintenance process management and maintenance resources management. Asset operation management is used to track the technical aspects of the maintenance process while maintenance process management and maintenance resources management are used to track the soft aspects of the maintenance process.
The third level is a further breakdown of the second-level categories. That is, asset operation management is broken down into five categories: overall asset, availability, reliability, maintainability and safety. Maintenance process management is broken down into five categories: maintenance management, maintenance planning, maintenance preparation, maintenance execution and maintenance assessment while maintenance resources management is broken down into three categories: spare parts management, outsourcing management and human resources management (See Figure 5.1).
In level four, the KPIs are grouped into common measures.
Asset operation management KPIs measure maintenance performance relative to the equipment condition. This level takes into consideration standards such as RAMS and BS EN 15341. Maintenance process management KPIs measure the efficiency and effectiveness of the consistent application of maintenance and maintenance support for both in-depth planning and execution of the maintenance process. This level takes into consideration the IEV standard and BS EN 15341. Its five classifications are tailored around the maintenance process implementation of the IEV standard while the actual
Chapter 5 Results and Discussion
46
KPIs are created by consulting BS EN 15341, internal documents from LKAB and LKAB supervisors. Maintenance resources management KPIs measure spare part management, internal maintenance personnel management and external maintenance personnel management. This level considers the IEV standard and the BS EN 15341 standard.
Details in the proposed KPI framework could be found in section 5.1.2, section 5.1.3 and section 5.1.4, as well as figures in Appendix.
Overall Asset
Availability
Maintenance Management
Maintenance Planning
Maintenance Preparation
Maintenance Execution
Maintenance Assessment
Spare Parts Management
Outsourcing Management
Human Resources
Management
Reliability
Maintainability
Safety
Ass
et M
anag
emen
t
Ass
et O
pera
tion
Man
agem
ent
Mai
nten
ance
Pro
cess
Man
agem
ent
Mai
nten
ance
Res
ourc
es
Man
agem
ent
Shutdown Statistics Failure Related
Operational Availability
Mean Reliability Measures
Failure Related
Mean Maintainability Measures
Occupational Safety
Maintenance Strategy
Quantity Related
Time RelatedResource Related
Cost Related
Work Order Creation
Work Order Feedback
Work Order Approval
Quantity Related
Time RelatedResource Related
Cost Related
Quality Effectiveness
Inventory Management
Contractor Statistics
Skills Management
Workload Management
Training Management
Competence Development
Level 1 Level 2 Level 3 Level 4
Figure 5.1 KPI framework
KPI framework for maintenance management through eMaintenance
47
5.1.2 DevelopmentofassetoperationmanagementKPIs
Asset as used here refers to physical parts, components, devices, subsystems, functional units, equipment or systems that can be individually described and accounted for. Asset operation management as used in this framework refers to technical KPIs used to measure asset overall asset, availability, reliability, maintainability and safety.
The technical KPIs are introduced are introduced in this part of the framework (see Table 5.1.1). The purpose of asset operation management is to provide KPIs for overall asset, availability, reliability, maintainability and safety. These indicators will provide maintenance managers with insight into routine maintenance and help them make cost-effective decisions on the operation, maintenance, upgrading and disposal of equipment. The asset operation management KPIs will help to put in place practices to improve availability, reliability, maintainability and safety.
Table 5.1.1: Asset operation management KPIs in Levels 3 and 4
LevelName Context Purpose
3 4
Ove
rall
Ass
et
Shut
dow
n St
atis
tics
Number of Shutdowns
This is the total number of times the asset is out of service.
Helps to understand the number of times the equipment, production line or process unit is out of service during the query period.
Total Shutdown Time
This is the total number of hours the assets are out of service.
Helps to estimate the total loss of the equipment in terms of time during the query period.
Average Shutdown Time
This is the ratio of total shutdown time to number of shutdowns.
Helps to understand the mean time of each shutdown, especially for the failed asset.
Failu
re R
elat
ed
Downtime Ratio/Frequency
This is the ratio of the number of times the equipment, production line or process unit is not producing because it is broken, under repair or idle to the total production time.
Helps to understand the proportion of failures in the total number of stops.
Downtime Ratio/Time
This is the ratio of the number of hours the equipment, production line or process unit is not producing because it is broken down, under repair or idle to the total number of work hours.
Helps to understand the proportion of failures in the total number of stops in terms of time.
Failure Mode Reporting Rate
This is the amount of corrective maintenance work whose failure mode is known.
Helps to understand the proportion of corrective maintenance work orders with failure mode information.
Reason for Failure
Registration Rate
This is the amount of corrective maintenance work with descriptions.
Helps to understand the proportion of work orders entered during the corrective maintenance work with information on causes of failure.
Chapter 5 Results and Discussion
48
Ava
ilabi
lity
Ope
rati
onal
Ava
ilabi
lity
Availability
This is the assetβs ability to perform as and when required, under given conditions, assuming that the necessary external resources are provided.
Helps to understand the availability of a product line or equipment.
Rel
iabi
lity
Mea
n R
elia
bilit
y M
easu
res
Mean Time Between Failure
This is the average time between failures of repairable assets and components.
Helps to understand the average time between unexpected breakdowns of an asset or production stoppages of asset.
Mean Time To Failure
This is the average time to failure for non-repairable assets.
Helps to understand the average time that a system is not failed, or is available
Mean Up Time This is the mean time from the system (subsystem) repair to next system (subsystem) failure.
Helps to understand the average time during which a system is in operation.
Failu
re R
elat
ed
Emergency Failure Ratio
This is the proportion of emergency failures in the work orders.
Helps to understand the proportion of emergency failures out of all failures that have occurred.
Emergency Failed
Equipment Ratio
This is the proportion of failed assets in emergency failure work orders.
Helps to understand the proportion of failed assets in emergency failures.
Corrective Maintenance Failure Rate
This is the total number of maintenance actions on failed assets.
Helps to understand the frequency of corrective maintenance activities.
Repeat Failure This is the total number of maintenance actions on failures that occur more than one time.
Helps to understand the proportion of failure modes that occur more than once in the total failure.
Mai
ntai
nabi
lity
Mea
n M
aint
aina
bilit
y M
easu
res
Mean Downtime
This is the mean time that an equipment, production line or process unit is non-operational for reasons other than repair, such as maintenance, and includes the time from failure to restoration of an asset or component.
Helps to understand the average total downtime required to restore an asset to its full operational capabilities.
Mean Time Between
Maintenance
This is the average length of operating time between one maintenance action and another maintenance action for a component.
Helps to understand the average time that a maintenance action needs to fix the failed component or the lowest replaceable unit.
Mean Time To Maintain
This is the average time to maintenance.
Helps to understand the average maintenance duration of equipment.
Mean Time To Repair
This is the average time that a repairable or non-repairable asset and\or component takes to recover from failure.
Helps to understand the average time required to troubleshoot and repair failed equipment and return it to normal operating conditions.
False Alarm Rate
This is the proportion of unwanted alarms given in error for an equipment, production line or process unit.
Helps to understand the number of false positives that occurred for an asset.
KPI framework for maintenance management through eMaintenance
49
Safe
ty
Occ
upat
iona
l Saf
ety
Number of Safety Incidents
This is the total number of safety incidents that have occurred during maintenance activities.
Helps to understand the number of safety incidents.
Injury Ratio This is the ratio of maintenance personnel injuries to total work hours.
Helps to understand the number of injuries that maintenance personnel sustained on the job.
Injury Ratio per Failure
This is the ratio of failures causing injuries to the total number of failures.
Helps to understand the number of injuries that maintenance personnel sustained compared to the total number of failures.
5.1.3 DevelopmentofmaintenanceprocessmanagementKPIs
Maintenance process management is the process of facilitating all aspects of day-to-day maintenance management activities, including job planning, scheduling, allocation, issuing work orders, execution, and task follow up. Maintenance process management as used in this framework uses βsoftβ KPIs to measure the effectiveness of the maintenance process.
The purpose of this section of the framework is to provide KPIs for in-depth management of the maintenance process, from maintenance strategy to maintenance planning, maintenance preparation, maintenance execution and assessment of maintenance effectiveness. These indicators will provide maintenance managers with insight into routine maintenance and help them make decisions on deploying maintenance personnel and which parts of the maintenance process to outsource. They will be able to address maintenance needs, thereby improving the maintenance process (see Table 5.1.2).
Table 5.1.2 Maintenance process management KPIs in Levels 3 and 4
LevelName Context Purpose
3 4
Mai
nten
ance
Man
agem
ent
Mai
nten
ance
Str
ateg
y
Critical Equipment Ratio
This is the amount of equipment important to performance, capacity, and throughput and vital to operating all equipment in the companyβs plant.
Helps to understand the proportion of critical equipment in the plant or processing unit.
Preventive Maintenance
Rate
This is the proportion of maintenance work carried out at predetermined intervals or according to prescribed criteria, intended to reduce the probability of failure or degradation of asset.
Helps to understand the proportion of equipment with a proactive maintenance strategy in the plant or processing unit.
Predictive Maintenance (PdM) Rate
This is the proportion of condition-based maintenance carried out following a forecast derived from repeated analysis or known characteristics and evaluation of the significant parameters of degrading asset.
Helps to understand the proportion of equipment with a predictive maintenance policy in the plant or processing unit.
Chapter 5 Results and Discussion
50
Preventive Maintenance Rate (Critical Equipment)
This is the proportion of maintenance carried out at predetermined intervals or according to prescribed criteria, intended to reduce the probability of failure or degradation of the asset.
Helps to understand the proportion of critical equipment with a proactive maintenance strategy in the plant or processing unit.
Predictive Maintenance Rate (Critical Equipment)
This is the proportion of condition-based maintenance carried out following a forecast derived from repeated analysis or known characteristics and evaluation of the significant parameters of the degrading asset.
Helps to understand the proportion of critical equipment with a predictive maintenance policy in the plant or processing unit.
Run to Failure (RTF) Ratio for
Critical Equipment
This is the ratio of failure management policy for critical equipment without any attempt to anticipate or prevent failure to all policies for critical equipment.
Helps to understand the proportion of critical equipment that does not have any precautionary or predictive maintenance policy in the plant or processing unit.
Planned Maintenance vs
Unplanned Maintenance
This is the ratio of planned maintenance to unplanned maintenance.
Helps to understand the relationship between planned maintenance and unplanned maintenance.
Mai
nten
ance
Pla
nnin
g
Qua
ntit
y R
elat
ed
Number of Planned Work Orders Created
This is the total number of work orders that have been scheduled.
Helps to understand the amount of scheduled maintenance/maintenance work.
Tim
e R
elat
ed
Average Planned Execution Time
This is the mean execution time of all planned work orders.
Helps to understand the average planned execution time of planned maintenance/maintenance work.
Res
ourc
e R
elat
ed
Total Number of Planned Internal
Labour Hours
This is the sum of labour hours attributed to planned maintenance work done by internal maintenance personnel.
Helps to understand the planned man-hours required for planned internal maintenance.
Average Planned Internal Labour
Hours
This is the mean hours for planned internal labour.
Helps to understand the mean man-hours required for planned internal maintenance.
Total Number of Planned External
Labour Hours
This is the sum of labour hours attributed to planned maintenance work by external maintenance personnel.
Helps to understand the planned labour hours required for maintenance work by external maintenance personnel.
Average Planned External Labour
Hours
This is the mean labour hours for planned external labour.
Helps to understand the average time required for planned maintenance by external maintenance personnel.
Planned Number of Materials Used
This is the sum of all materials scheduled to be used for maintenance and/or maintenance work.
Helps to understand the number of spare parts used in the planned maintenance.
KPI framework for maintenance management through eMaintenance
51
Average Planned Number of
Materials Used
This is the mean number of materials to be used for scheduled maintenance and/or maintenance work.
Helps to understand the average number of spare parts used for planned maintenance.
Cost
Rel
ated
Total Cost of Planned Human
Resources
This is the total cost of manpower used for scheduled maintenance and/or maintenance work.
Helps to understand the manpower cost of planned maintenance.
Average Planned External Human Resource Costs
This is the mean external manpower cost for scheduled maintenance and/or maintenance work.
Helps to understand the average planned manpower cost of external labour for planned maintenance.
Total Cost of Planned
Materials
This is the total cost of materials needed for scheduled maintenance and/or maintenance work.
Helps to understand the cost of materials for planned maintenance.
Planned Average Material Cost
This is the mean cost of materials for scheduled maintenance and/or maintenance work.
Helps to understand the mean planned cost of materials for each scheduled repair or maintenance activity.
Labour Cost Ratio
This is the ratio of manpower cost to the total cost of planned maintenance.
Helps to understand the ratio of manpower cost to total planned cost in planned maintenance.
Planned Material Cost Ratio
This is the ratio of planned material cost to the planned total cost of maintenance.
Helps to understand the proportion of the total costs of planned material allocated to planned maintenance.
Mai
nten
ance
Pre
para
tion
Wor
k O
rder
Cre
atio
n
Planned Start / End Time
Registration Rate
This is the ratio of work orders whose planned start/ end time is known at the time of creation to the total work orders created.
Helps to understand the amount of work orders whose planned start and end time are provided during their creation.
Planned Spare Parts
Registration Rate
This is the ratio of work orders whose spare parts requirement are known at the time of the work order creation to the total work orders created.
Helps to know the planned spare parts registration rate of work orders.
Planned Man-Hour
Registration Rate
This is the number of work orders with labour hours needed recorded during work order creation out of all the work orders created.
Helps to understand the proportion of work orders with the required labour registered during work order creation.
Planned Downtime
Registration Rate
This is the ratio of hours that the plant or asset will be down ahead of time to the total work hours.
Helps to understand the percentage of work orders with planned downtime entered during work order creation.
Standard Operating Plan
Registration Rate
This is ratio of the number of work orders with an SOP to the total work orders.
Helps to understand the proportion of work orders with standard operating procedure plans.
Planned Work Type
Registration Rate
This is the proportion of work orders with required skills registered during their creation.
Helps to understand the proportion of work orders with known skills required in the work category.
Job Priority Registration Rate
This is the number of work orders with job priorities assigned during the work order
Helps to understand the proportion of work orders assigned work priorities during work order creation.
Chapter 5 Results and Discussion
52
creation out of all the work orders.
Wor
k O
rder
Fee
dbac
k Actual Spare
Parts Use Registration Rate
This is the amount of spare parts used for maintenance work.
Helps to understand the actual use of spare parts for maintenance jobs.
Actual Man-Hour Registration Rate
This is the proportion of labour used for maintenance work.
Helps to understand the amount of labour used for maintenance tasks.
Actual Downtime Registration Rate
This is the number of work orders causing actual downtime.
Helps to understand the proportion of work orders that lead to downtime.
Work Order Registration
Back-Log
This is the difference between work order registration date and the actual registration date of the work order.
Helps to understand the time interval between the completion of the work order and the completion of registration in the system.
Wor
k O
rder
App
rova
l
Total Number of Work Orders
This is the sum of proposed work orders that have been registered.
Helps to understand the total number of work orders reported.
Total Number of Approved Work
Orders
This is the sum of proposed work orders that have been approved.
Helps to understand the total number of work orders approved in a single pass.
Total Number of Unapproved Work Orders
This is the sum of proposed work orders that have not been approved.
Helps to understand the total number of work orders not approved in a single pass.
Work Order Approval Ratio
This is the ratio of proposed work orders to planned work orders.
Helps to understand the proportion of reported work orders against the total planned work orders.
One-time Approved Work
Order Ratio
This is the ratio of work orders proposals that were approved once to actual work orders.
Helps to understand the rate of one-time approvals for work orders submitted.
Average time lag for Reporting
and Approving Work Orders
This is the difference between approved work orders and proposed work orders.
Helps to understand the average time between submission of a work order and the approval of the issuance of the work order.
Mai
nten
ance
Exe
cuti
on
Qua
ntit
y R
elat
ed
Number of Planned Work
Orders Completed
This is the total number of preventive maintenance work orders that have been resolved.
Helps to understand the planned maintenance work done.
Number of Unplanned Work
Orders Completed
This is the total number of unplanned corrective work orders that have been resolved.
Helps to understand the amount of unplanned maintenance work completed.
Number of Work Orders
Completed Per Shift
This is the total number of work orders completed per shift.
Helps to understand the number of work orders completed in a shift.
Work Order Resolution Rate
This is the ratio of the number of work orders performed as scheduled to the total number of scheduled work orders.
Helps to understand the ratio of the number of work orders completed as scheduled.
Tim
e R
elat
ed
Average Work Order Time
This is the mean execution time for completed work orders.
Helps to understand the average execution time of completed maintenance work.
Average Waiting Time for
Personnel
This is the mean waiting time for maintenance personnel needed to resolve a maintenance
Helps to understand the average logistical waiting time for maintenance staff for completed maintenance work.
KPI framework for maintenance management through eMaintenance
53
request. Average Waiting Time for Spare
Parts
This is the mean waiting time for spare parts used for completed maintenance work.
Helps to understand the waiting time for spare parts for maintenance work.
Personnel Waiting Time
Ratio
This is the proportion of time it takes to get maintenance personnel to resolve a maintenance task.
Helps to understand the staff waiting time for maintenance work completed.
Spare Parts Waiting Time
Ratio
This is the proportional waiting time for spare parts used for maintenance work.
Helps to understand the spare parts waiting time for completed maintenance work.
Average Maintenance Outage Time
This is the period of time that the asset fails to provide or perform its primary function during maintenance work.
Helps to understand the average execution time of the maintenance work.
Average Waiting Time of
Personnel during Shutdown
This is the mean waiting time for maintenance personnel during shutdown.
Helps to understand the average logistic waiting time for maintenance personnel for maintenance work during shutdown.
Average Waiting Time for Spare
Parts during Shutdown
This is the mean waiting time for spare parts during shutdown.
Helps to understand the average waiting time for spare parts used for completing maintenance work at shutdown.
Average Waiting Time of
Personnel during Shutdown Ratio
This is the mean waiting time for maintenance personnel to mean maintenance outage time during shutdown.
Helps to understand the ratio of waiting time for personnel who have completed the maintenance work at shutdown to the total repair time.
Average Waiting Time for Spare
Parts during Shutdown Ratio
This is the ratio of the mean waiting time for spare parts to the mean maintenance outage time.
Helps to understand the ratio of spare parts waiting time for the repair/maintenance work to total maintenance outage time during the query period.
Estimated Time vs. Actual Time
This is the difference between actual maintenance time and planned maintenance time.
Helps to understand the time variances in work orders.
Res
ourc
e R
elat
ed
Total Number of Internal Labour
Hours
This is the sum of hours used by in-house maintenance personnel for maintenance work.
Helps to understand the total number of hours used by in-house maintenance personnel for maintenance work performed.
Average Internal Labour Hours
Used
This is the mean number of hours used by in-house maintenance personnel for maintenance work.
Helps to understand the average labour hours used for each completed internal maintenance work.
Total Number of External Labour
Hours
This is the sum of hours used by maintenance contractors for maintenance work.
Helps to understand the labour hours used for external maintenance work.
Average External Labour Hours
Used
This is the mean hours used by external maintenance personnel for maintenance work.
Helps to understand the average labour hours for each completed external maintenance action.
Number of Materials Used
This is the total number of spare parts used for maintenance work.
Helps to understand the actual number of spare parts used for maintenance work.
Chapter 5 Results and Discussion
54
Average Materials Used
This is the mean number of spare parts used for maintenance work.
Helps to understand the average number of spare parts used for each completed maintenance action.
Cost
Rel
ated
Total Cost of External Human Resources Used
This is the total cost of using maintenance contractors for maintenance work.
Helps to understand the cost of external labour for completed maintenance work.
Average External Human
Resources Costs
This is the mean cost of external maintenance contractors for maintenance work.
Helps to understand the average external labour costs for maintenance work completed.
Total Cost of Materials Used
This is the total cost of materials used for maintenance.
Helps to understand the cost of materials used for maintenance work completed.
Average Cost of Materials Used
This is the mean cost of materials used for maintenance work.
Helps to understand the average cost of materials for completed maintenance work.
External Labour Costs Ratio
This is the ratio of the total external maintenance contractor cost to the total maintenance cost.
Helps to understand the ratio of manpower cost to total cost of maintenance work completed
Actual Materials Cost Ratio
This is the ratio of costs for materials to the total maintenance cost.
Helps to understand the cost of the materials used to complete the maintenance work.
Maintenance Cost per Asset
This is the total cost incurred for maintaining an asset.
Helps to understand the cost incurred for maintenance work.
Mai
nten
ance
Ass
essm
ent
Qua
lity
Number of Completed Work Orders Approved
This is the total number of completed work orders that have been approved after resolution.
Helps to understand the total number of reported approvals for completed work orders.
Work Order Approval Ratio
This is the ratio of completed work orders that need to be approved after resolution to total completed work orders.
Helps to understand the proportion of the work orders that need to be submitted for approval.
One-Time Pass Internal
Completion Rate
This is the ratio of work orders that are resolved the very first time they occur by internal maintenance personnel to total completed work orders.
Helps to understand the number of one-time work orders by internal maintenance personnel that do not need to be reworked.
One-Time Pass External
Completion Rate
This is the ratio of work orders that are resolved the very first time they occur by external maintenance personnel to total completed work orders.
Helps to understand the number of one-time work orders by external maintenance personnel that do not need to be reworked.
Planning Compliance
This is a measure of adherence to maintenance plans.
Helps to understand the amount of planned maintenance work that is started on the same date as planned.
Effe
ctiv
enes
s
Internal Work Completion Rate
This is the ratio of successful work completed by internal maintenance personnel to total completed work.
Helps to understand the proportion of work orders completed by internal maintenance personnel.
Outsourced Work
Completion Rate
This is the ratio of successful work completion by external maintenance personnel to total completed work.
Helps to understand the proportion of work orders completed by external maintenance personnel.
Internal Work This is the ratio of delayed Helps to understand completion delays
KPI framework for maintenance management through eMaintenance
55
Delay Rate maintenance work by internal maintenance personnel to all internal maintenance.
in internal maintenance work.
Internal Work Average Delay
Period
This is the mean period of delayed work by internal maintenance personnel.
Helps to understand the average delay period of the work orders scheduled to be completed by internal maintenance personnel.
External Work Delay Rate
This is the ratio of delayed maintenance work by external maintenance personnel to all external work.
Helps to understand the delayed completion of external work.
External Work Average Delay
Period
This is the mean period of delayed work by external maintenance personnel.
Helps to understand the average delay period of the work orders scheduled to be completed by external maintenance personnel.
Internal Average Execution Time Deviation Ratio
This is the difference in time between planned and actual maintenance jobs done by internal maintenance personnel.
Helps to understand the difference between the average execution time of the internal maintenance work and the planned time.
External Committee
Execution Time Deviation Ratio
This is the difference in time between planned and actual maintenance jobs done by external maintenance personnel
Helps to understand the difference between the average execution time and the planned time for the external maintenance work completed.
Internal Man-Hour Difference
Ratio
This is the difference in time between planned and actual labour hours used by internal maintenance personnel.
Helps to understand the deviations from the planned labour hours for internal maintenance work.
Internal Average Man-Hour
Difference Ratio
This is the mean difference in time between planned and actual labour hours used by internal maintenance personnel.
Helps to understand the average deviation from the planned average for each completed internal maintenance action.
External Man-Hour Difference
Ratio
This is the difference in time between planned and actual labour hours of external maintenance personnel.
Helps to understand the deviation between actual and planned labour hours for external maintenance work.
External Average Man-Hour
Difference Ratio
This is the mean difference in time between planned and actual labour hours of external maintenance personnel.
Helps to understand the average deviation from the planned average for each external maintenance action.
Material Difference Ratio
This is the difference between planned spare parts and actual spare parts used for maintenance work.
Helps to understand the difference between the actual number of spare parts used for maintenance work and the number of spare parts assigned in the plan.
Average Material Difference Ratio
This is the mean difference between planned spare parts and actual spare parts used for maintenance work.
Helps to understand the difference between the average number of used spare parts and the planned average for each completed maintenance action.
Chapter 5 Results and Discussion
56
5.1.4 DevelopmentofmaintenanceresourcemanagementKPIs
Maintenance resources management as used in this framework refers to metrics for tracking maintenance spare parts, outsourced maintenance personnel, internal maintenance personnel, training and training quality of maintenance personnel. Maintenance resources management uses soft KPIs to measure asset resources used for maintenance.
This part of the framework introduces KPIs for tracking spare parts consumption, external maintenance personnel, and internal maintenance personnel. It also includes KPIs that track workload and training of maintenance personnel. These KPIs form part of the business KPIs, to which the mining company refers as soft KPIs based on its business strategies. The purpose of maintenance resource management is to provide KPIs that can measure spare parts usage, the maintenance personally available for maintenance work, the workload of maintenance personnel, and the efficiency and effectiveness of maintenance training. These indicators give maintenance managers insight into what skill sets are needed, when to employ more maintenance personnel and what maintenance training is required to support maintenance in an efficient way (see Table 5.1.3).
Table 5.1.3 Maintenance resources management KPIs in Level 3 and Level 4
LevelName Context Purpose
3 4
Spar
e Pa
rts
Man
agem
ent
Inve
ntor
y M
anag
emen
t
Average Spare Part Quantity
This is the mean number of spare parts in stock.
Helps to understand the average number of spare parts between opening and closing stock.
Spare Part Capital Utilization
This is the mean cost of spare parts utilization.
Helps to understand the average inventory value of the spare parts used compared to the original purchase cost of the equipment.
Spare Parts Capital Replacement Rate
This is the average cost of spare part replacement.
Helps to understand the average inventory cost of replacing spare parts.
Spare Part Consumption per
Thousand SEK Output
This is the average cost of spare parts for maintenance work per every 1000 SEK output.
Helps to understand the average cost of spare parts for maintenance for every thousand SEK spent on overall maintenance.
Spare Part Turnover Rate
This is the number of spare parts bought to replace failed parts in a quarter or a year.
Helps to understand spare parts turnover rate.
Spare Part Turnover Period
This is the ratio of average inventory value to cost of spare parts within the year.
Helps to understand the spare parts turnover period.
Slow Moving Inventory Ratio
This is the proportion of stock that has not shipped in a certain amount of time, e.g. 90days or 180 days, and includes stock with a low turnover rate relative to the quantity on hand.
Helps to understand periods of no consumption of some types of spare parts from the total spare parts inventory.
KPI framework for maintenance management through eMaintenance
57
Out
sour
cing
Man
agem
ent
Cont
ract
or S
tati
stic
s
Number of Outsourced Equipment
Breakdowns
This is the total amount of outsourced equipment that is out of service.
Helps to understand the total amount of equipment handled by outsourced maintenance personnel that is not working.
Number of Outsourced
Maintenance Personnel
This is the total number of outsourced maintenance personnel.
Helps to understand the total number of external maintenance personnel.
External Maintenance Cost
Ratio
This is the ratio of cost of outsourced maintenance personnel to the overall maintenance cost.
Helps to understand the cost of external maintenance personnel.
Hum
an R
esou
rces
Man
agem
ent
Skill
s M
anag
emen
t
Total Number of Maintenance
Operators
This is the number of maintenance operators used for maintenance tasks.
Helps to understand the total number of registered maintenance operators assigned to tasks.
Total Number of Maintenance
Engineers
This is the number of maintenance engineers used for maintenance tasks.
Helps to understand the total number of registered maintenance engineers assigned to tasks.
Number of Multi-Skilled
Maintenance Personnel
This is the number of multi-skilled maintenance personnel used for maintenance tasks.
Helps to understand the total number of registered skilled maintenance personnel assigned to tasks.
Maintenance Operator Ratio
This is the ratio of maintenance operators to total maintenance personnel.
Helps to understand the percentage of maintenance personnel who are operators.
Maintenance Engineer Ratio
This is the ratio of maintenance engineers to total maintenance personnel.
Helps to understand the percentage of maintenance personnel who are engineers.
Multi-Skilled Maintenance
Personnel Ratio
This is the ratio of multi- skilled maintenance personnel to total maintenance personnel.
Helps to understand the percentage of maintenance personnel who are multi-skilled.
Wor
k Lo
ad M
anag
emen
t
Average Number of Work Orders
Created per Person
This is the number of work orders created by each maintenance worker.
Helps to understand the average number of work orders created by each maintenance worker.
Average Number of Work Orders Executed per
Person
This is the number of work orders completed per maintenance worker.
Helps to understand the average number of work orders completed by each maintenance worker.
Average Daily Workload per
Person
This is the number of hours for each maintenance worker in a day.
Helps to understand the daily average number of work hours for the implementation of work orders for each maintenance person.
Tra
inin
g
Average Annual Training Hours per
Maintenance Operator
This is the yearly mean training hours per maintenance operator.
Helps to understand the average annual training hours for maintenance operators.
Average Annual Training Hours per
Maintenance Engineers
This is the yearly mean training hours per maintenance engineer.
Helps to understand the average annual training hours for maintenance engineers.
Average Annual Training Hours per
Multi-Skilled Maintenance
Engineers
This is the yearly mean training hours per multi-skilled maintenance engineer.
Helps to understand the average annual training hours for multi-skilled maintenance engineers.
Chapter 5 Results and Discussion
58
Com
pete
nce
Dev
elop
men
t
Number of New Senior
Maintenance Engineers
This is the number of maintenance operators who have become maintenance engineers.
Helps to understand the total number of maintenance operators who have risen to the rank of maintenance engineers.
Ratio of New Senior
Maintenance Engineers
This is the ratio of the number of maintenance operators who have become maintenance engineers to the total number of maintenance engineers.
Helps to understand the proportion of maintenance operators who have risen up to the rank of maintenance engineers.
Number of New Multi-Skilled Maintenance
Engineers
This is the number of maintenance engineers who have become multi-skilled maintenance engineers.
Helps to understand the total number of maintenance engineers who have risen to the rank of multi-skilled maintenance engineers.
Ratio of New Multi-Skilled
Maintenance Engineers
This is the ratio of the number of maintenance engineers who have become multi-skilled maintenance engineers to the total number of multi-skilled maintenance engineers.
Helps to understand the proportion of maintenance engineers who have risen to the rank of multi-skilled maintenance engineers.
5.2 ResultsanddiscussionrelatedtoRQ2
RQ2: How can the developed KPI framework be implemented through eMaintenance?
The second research question is answered by proposing data sources, time definitions, and a general formula for all the KPIs developed in the new framework in Paper A. Results of this part will further support to develop KPI ontology and taxonomy of the proposed KPI framework for its implementation in an eMainteannce environement. Results are shown in Table 5.2.1, Table 5.2.2 and Table 5.2.3.
5.2.1 KPIimplementationforassetoperationmanagement
This section presents the results of KPI implementation for asset operation management; it provides data sources, time definitions and a general formula for the related KPIs. These are shown in Table 5.2.1.
Table 5.2.1 Implementation in an eMaintenance environment for asset operation management
LevelName Timeline GeneralFormula
3 4
Ove
rall
Ass
et
Shut
dow
n St
atis
tics
Number of Shutdowns
Stop date/ Registration date β (query start date, query termination date)
ππ’π ππ’ππππ ππ π ππππ π‘ππππ ππ‘πππ
Total Shutdown Time
Registration date / stop record date β (query start date, query termination date)
ππ’π π ππππ π‘ππππ ππ‘ππ ππππ
Average Shutdown Time
Registration date / stop record date β (query start date, query termination date)
ππ’π π ππππ π‘ππππ ππ‘ππ ππππ πΆππ’ππ‘ ππ’ππππ ππ π ππππ π‘ππππ ππ‘πππ
KPI framework for maintenance management through eMaintenance
59
Failu
re R
elat
ed
Downtime Ratio/Frequency
Registration date / stop record date β (query start date, query termination date)
ππ’π ππ’ππππ ππ π ππππ π‘ππππ ππ‘πππ πβπππ ππ β²πππ’ππ‘ ππππβ²
ππ’π ππ’ππππ ππ π ππππ π‘ππππ ππ‘πππ
Downtime Ratio/Time
Registration date / stop record date β (query start date, query termination date)
ππ’π π ππππ π‘ππππ ππ‘ππ πππππβπππ ππ β²πππ’ππ‘ ππππβ²
ππ’π π ππππ π‘ππππ ππ‘ππ ππππ
Failure Mode Reporting Rate
Work order registration /creation date β (query start date, query termination date) Item: Work order type; System/section; Work for supplier group; Work supplier attribute
πΆππ’ππ‘ ππ’ππππ ππ ππππ ππππππ πβπππ ππ πππππππ‘ππ£π
πππ πππππ’ππ ππππ ππ πππ‘ πππΏπΏπΆππ’ππ‘ ππ’ππππ ππ ππππ ππππππ
πβπππ ππ β²πππππππ‘ππ£πβ²
Reason for Failure
Registration Rate
work order registration date β (query start date, query termination date)
πΆππ’ππ‘ ππ’ππππ ππ ππππ ππππππ πβπππ ππ πππππππ‘ππ£π πππ πππππ’ππ ππππ ππ ππ πππ‘ πππΏπΏ
πΆππ’ππ‘ ππ’ππππ ππ ππππ ππππππ πβπππ ππ β²πππππππ‘ππ£πβ²
Ava
ilabi
lity
Ope
rati
onal
A
vaila
bilit
y
Availability
Registration date / stop record date β (query start date, query termination date)
πππ‘ππ ππππππ‘πππ πππππππ‘ππ ππππππ‘πππ ππππ
π·ππ€π π‘πππ π·π’π π‘π πππππ‘ππππππ
Rel
iabi
lity
Mea
n R
elia
bilit
y M
easu
res Mean Time
Between Failure
Registration date / stop record date β (query start date, query termination date)
ππ’π ππππππ‘πππ πππππβπππ ππ‘ππ ππ ππππππππππ
πΆππ’ππ‘ ππ’ππππ ππ πΉππππ’πππ
Mean Time To Failure
Registration date / stop record date β (query start date, query termination date)
ππ’π ππππππ‘πππ πππππβπππ ππ‘ππ ππ πππ‘ πππππππππππΆππ’ππ‘ ππ’ππππ ππ πΉππππ’πππ
Mean Up Time
Registration date / start record date β (query start date, query termination date)
ππ’π πππ‘πππ ππ π»ππ’ππ ππ’ππππ ππ πππ‘πππ πΈπ£πππ‘π
Failu
re R
elat
ed
Emergency Failure Ratio
Work order registration/creation date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ ππππ ππππππ πβπππ ππ
β²πππππππππ¦ ππππππ π€πππ πππππβ²πΆππ’ππ‘ ππ’ππππ ππ ππππ ππππππ
Emergency Failed Equipment Ratio
Work order registration/creation date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΈππ’ππππππ‘ πβπππ ππ
β²πππππππππ¦ ππππππ π€πππ πππππβ² πΆππ’ππ‘ ππ’ππππ ππ ππππ ππππππ
Corrective Maintenance Failure Rate
Work order registration/creation date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ ππππ ππππππ πβπππ ππ β²πππππππ‘ππ£πβ²
πΆππ’ππ‘ ππ’ππππ ππ ππππ ππππππ
Repeat Failure
Work order registration/creation date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ ππππ ππππππ πβπππ πππππ’ππ ππππ 1
πΆππ’ππ‘ ππ’ππππ ππ ππππ ππππππ πβπππ ππ β²πππππππ‘ππ£πβ²
Chapter 5 Results and Discussion
60
Mai
ntai
nabi
lity
Mea
n M
aint
aina
bilit
y M
easu
res
Mean Downtime Registration date / stop record date β (query start date, query termination date)
ππ’π π·ππ€ππ‘πππ ππ π»ππ’ππ ππ’ππππ ππ π·ππ€ππ‘πππ πΈπ£πππ‘π
Mean Time Between
Maintenance
Registration date / start record date β (query start date, query termination date)
ππ’π πππ‘πππππ’ππππ ππ πππππ‘ππππππ π΄ππ‘ππππ
Mean Time To Maintain
Registration date / stop record date β (query start date, query termination date)
ππ’π βπβ πΌππππ£πππ’ππ ππππ‘ πππππ π‘π πππππ‘ππππππ πΆππ’ππ‘ βπβ ππππ‘π
Mean Time To Repair
Registration date / stop record date β (query start date, query termination date)
ππ’π βπβ πΌππππ£πππ’ππ ππππ‘ πππππ π‘π π ππ π‘πππ
πΆππ’ππ‘ βπβ ππππ‘π
False Alarm Rate
Registration date β (query start date, query termination date)
πΆππ’ππ‘ ππ’ππππ ππ πΉπππ π π΄πππππ πππ‘ππ ππ’ππππ ππ π΄πππππ
Safe
ty
Occ
upat
iona
l Saf
ety
Number of Safety Incidents
Registration date β (query start date, query termination date)
πΆππ’ππ‘ ππ’ππππ ππ πππππ‘π¦ πΌπππππππ‘π
Injury Rate
Registration date β (query start date, query termination date)
πΆππ’ππ‘ ππ’ππππ ππ πππππ‘π¦ πΌπππππππ‘π πβπππ πΌπππ’ππ¦
πππ‘π€πππ β²πππ‘π 1β² πππ β²πππ‘π 2β²ππ’π πππππππ π»ππ’ππ
Injury Rate per Failure
Registration date β (query start date, query termination date)
πΆππ’ππ‘ ππ’ππππ ππ πΉππππ’πππ πΆππ’π πππ πΌπππ’ππ¦
πππ‘ππ ππ’ππππ ππ πΉππππ’πππ β 100
5.2.2 KPIimplementationformaintenanceprocessmanagement
This section presents the results of KPI implementation for maintenance process management; it presents data sources, time definitions and a general formula for the related KPIs. These are shown in Table 5.2.2.
Table 5.2.2 Implementation in an eMaintenance environment for Maintenance Process Management
LevelName Timeline GeneralFormula
3 4
Mai
nten
ance
Man
agem
ent
Mai
nten
ance
Str
ateg
y
Critical Equipment
Ratio
Registration date β (query start date, query termination date)
πΆππ’ππ‘ ππ’ππππ ππ πΈππ’ππππππ‘ πβπππ ππ β²πΆπππ‘ππππβ²
πΆππ’ππ‘ ππ’ππππ ππ πΈππ’ππππππ‘
Preventive Maintenance
Rate
Work order registration date β (query start date, query termination date)
πΆππ’ππ‘ ππ’ππππ ππ πΈππ’ππππππ‘ πβπππ ππ β²πππ‘π¦ππ π€πππ πππππβ²πΆππ’ππ‘ ππ’ππππ ππ πΈππ’ππππππ‘
Predictive Maintenance Rate (PdM)
Registration date β (query start date, query termination date)
πΆππ’ππ‘ ππ’ππππ ππ πΈππ’ππππππ‘ πβπππ ππ β²π π‘ππ‘π’π πππππ‘πππππ πππππ‘β²
πΆππ’ππ‘ ππ’ππππ ππ πΈππ’ππππππ‘
KPI framework for maintenance management through eMaintenance
61
Preventive Maintenance Rate (Critical Equipment)
Work order registration date β (query start date, query termination date)
πΆππ’ππ‘ ππ’ππππ ππ πΈππ’ππππππ‘πβπππ ππ β²πππ‘π¦ππ π€πππ πππππβ² β²ππππ‘ππππβ²
πΆππ’ππ‘ ππ’ππππ ππ πΈππ’ππππππ‘πβπππ ππ β²πΆπππ‘ππππβ²
Predictive Maintenance Rate (Critical Equipment)
Registration date β (query start date, query termination date)
πΆππ’ππ‘ ππ’ππππ ππ πΈππ’ππππππ‘πβπππ ππ β²ππππ‘ππππβ² ππ
β²π π‘ππ‘π’π πππππ‘πππππ πππππ‘ β² πΆππ’ππ‘ ππ’ππππ ππ πΈππ’ππππππ‘
πβπππ ππ β²ππππ‘ππππβ²
Run to Failure (RTF) Ratio for
Critical Equipment
Registration date β (query start date, query termination date)
πΆππ’ππ‘ ππ’ππππ ππ πΈππ’ππππππ‘πβπππ πΆπππ‘ππππ ππ ππ
β² π π‘ππ‘π’π πππππ‘πππππ πππππ‘ β² ππ ππ π€πππ πππππ
πΆππ’ππ‘ ππ’ππππ ππ πΈππ’ππππππ‘πβπππ ππ β²ππππ‘ππππβ²
Planned Maintenance vs
Unplanned Maintenance
Work order registration date β (query start date, query termination date)
ππ’π ππππ ππππππ πβπππ ππ_ππ¦ππ β²ππππβ²
ππ’π ππππ ππππππ πβπππ ππ_ππ¦ππ β²π’πππππππβ²
Mai
nten
ance
Pla
nnin
g
Qua
ntit
y R
elat
ed
Number of Planned Work Orders Created
Work order creation date β (query start date, query end date)
ππ’π ππππ ππππππ πβπππ ππ_ππ¦ππ β²ππππβ²
Tim
e R
elat
ed
Average Planned
Execution Time
Work order creation date β (query start date, query end date)
ππ’π πΈπ₯πππ’π‘πππ πππππβπππ ππ_ππ¦ππ β²ππππβ²
ππ’π ππππ ππππππ πβπππ ππ_ππ¦ππ β²ππππβ²
Res
ourc
e R
elat
ed
Total Number of Planned
Internal Labour Hours
Work order creation date β (query start date, query end date)
ππ’π πΏππππ’π π»ππ’ππ πβπππ π€πππ πππ‘πππππ¦ ββπΌππ‘πππππβ & ππ_ππ¦ππ
β²ππππβ²
Average Planned
Internal Labour Hours
Work order creation date β (query start date, query end date)
ππ’π πΏππππ’π π»ππ’ππ πβπππ π€πππ πππ‘πππππ¦
βπΌππ‘πππππβ ππ_ππ¦ππ β²ππππβ²πΆππ’ππ‘ ππππ ππππππ
πβπππ ππ_ππ¦ππ β²ππππβ²
Total Number of Planned
External Labour Hours
Work order creation date β (query start date, query end date)
ππ’π πΏππππ’π π»ππ’ππ πβπππ π€πππ πππ‘πππππ¦
βπΈπ₯π‘πππππβ² & ππ_ππ¦ππ β²ππππβ²
Chapter 5 Results and Discussion
62
Average Planned External
Labour Hours
Work order creation date β (query start date, query end date)
ππ’π πΏππππ’π π»ππ’ππ πβπππ π€πππ πππ‘πππππ¦
βπΈπ₯π‘πππππβ ππ_ππ¦ππ β²ππππβ²πΆππ’ππ‘ ππππ ππππππ
πβπππ ππ_ππ¦ππ β²ππππβ²
Planned Number of
Material Used
Work order creation date β (query start date, query end date)
ππ’π πππππ ππ’ππππ πβπππ ππ_ππ¦ππ β²ππππβ²
Average Planned
Number of Materials Used
Work order creation date β (query start date, query end date)
ππ’π πππππ ππ’πππππβπππ ππ_ππ¦ππ β²ππππβ²
πΆππ’ππ‘ ππππ ππππππ πβπππ ππ_ππ¦ππ β²ππππβ²
Cost
Rel
ated
Total Cost of Planned Human
Resources
Work order creation date β (query start date, query end date)
ππ’π πΏππππ’π π ππ‘π β πππππππ πΏππππ’π ππ’ππππ
πβπππ ππ β²ππππβ² & π€πππ πππ‘πππππ¦
β²ππ₯π‘πππππβ²
Average Planned External Human
Resource Costs
Work order creation date β (query start date, query end date)
ππ’π πΏππππ’π π ππ‘π β ππππ πΏππππ’π πππππβπππ ππ
β²ππππβ² π€πππ πππ‘πππππ¦ β²ππ₯π‘πππππβ²
πΆππ’ππ‘ ππ’ππππ ππ ππππ ππππππ πβπππ ππ
β²ππππβ² π€πππ πππ‘πππππ¦ β²ππ₯π‘πππππβ²
Total Cost of Planned
Materials
Work order creation date β (query start date, query end date)
ππ’π πππππ ππππ‘π ππ’πππ‘ππ‘π¦ β πππππ ππππ‘π πππππ
πβπππ ππ_ππ¦ππ β²ππππβ²
Planned Average
Material Cost
Work order creation date β (query start date, query end date)
ππ’π ππ’ππππ ππ πππππ ππππ‘π β πππππ πππππ πβπππ ππ
β²ππππβ²ππ’π ππ’ππππ ππ ππππ ππππππ
πβπππ ππ_ππ¦ππ β²ππππβ²
Labour Cost Ratio
Work order creation date β (query start date, query end date)
πππ‘ππ πΆππ π‘ ππ πππππππ π»π’πππ π ππ ππ’ππππ πππ‘ππ πΆππ π‘ ππ πππππππ π»π’πππ π ππ ππ’ππππ
πππ‘ππ πΆππ π‘ ππ πππππππ πππ‘ππππππ
Planned Material Cost
Ratio
Work order creation date β (query start date, query end date)
πππ‘ππ πΆππ π‘ ππ πππππππ πππ‘ππππππ πππ‘ππ πΆππ π‘ ππ πππππππ π»π’πππ π ππ ππ’ππππ
πππ‘ππ πΆππ π‘ ππ πππππππ πππ‘ππππππ
KPI framework for maintenance management through eMaintenance
63
Mai
nten
ance
Pre
para
tion
Wor
k O
rder
Cre
atio
n
Planned Start / End Time
Registration Rate
Work order registration/creation date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ πΆπ’πππππ‘ ππππ ππππππ
πβπππ βπππππππ π π‘πππ‘/πππ π‘πππβ ππ ππππππ πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ
πΆπ’πππππ‘ ππππ ππππππ
Planned Spare Parts
Registration Rate
Work order registration / creation date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ ππ’ππππ ππ πΆπ’πππππ‘ ππππ ππππππ
πβπππ β²π ππππ ππππ‘π ππππβ² ππ ππππππ πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ
πΆπ’πππππ‘ ππππ ππππππ
Planned Man-Hour
Registration Rate
Work order registration/creation date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ ππ’ππππ ππ πΆπ’πππππ‘ ππππ ππππππ
πβπππ βπππππππ πππππ’π βππ’ππ β ππ ππππππ πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ
ππ’ππππ ππ πΆπ’πππππ‘ ππππ ππππππ
Planned Downtime
Registration Rate
Work order registration/creation date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ πΆπ’πππππ‘ ππππ πππππ
πβπππ βπππππππ πππππ’π π‘πππβ ππ ππππππ πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ
πΆπ’πππππ‘ ππππ πππππ ππ’ππππ
Standard Operating Plan
Registration Rate
Work order registration/creation date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ πΆπ’πππππ‘ ππππ ππππππ
πβπππ βπ π‘ππππππ π€πππ ππππβ ππ πππ£ππ πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ
πΆπ’πππππ‘ ππππ ππππππ
Planned Work Type
Registration Rate
Work order registration/creation date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ ππ’ππππ ππ πΆπ’πππππ‘ ππππ ππππππ
πβπππ βπ€πππ πππ‘πππππ¦ ππππβ² ππ πππππππΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ
πΆπ’πππππ‘ ππππ ππππππ
Job Priority Registration
Rate
Work order registration/creation date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ πΆπ’πππππ‘ ππππ πππππ ππ’ππππ πβπππ β²πππ πππππππ‘π¦β² ππ πππ£ππ
πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ πΆπ’πππππ‘ ππππ πππππ
Wor
k O
rder
Fee
dbac
k
Actual Spare Parts Use
Registration Rate
Work order registration β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ πβπππ β²ππππ π’π π ππ π ππππ ππππ‘π β² ππ ππππππ
πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππππ πβπππ β²πππππ ππππ‘π ππππβ² ππ ππππππ
Actual Man-Hour
Registration Rate
Work order registration β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππππ πβπππ βπ€βππ π’π πππ ππππ’ππβ ππ πππππππΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππππ
Actual Downtime
Registration Rate
Work order registration β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππππ πβπππ βπππ‘π’ππ πππ€ππ‘πππβ ππ ππππππ
πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππππ πβπππ βπππππππ πππ€ππ‘πππβ ππ ππππππ
Work Order Registration
Back-Log
Work order registration β (query start date, query end date)
ππππ πππππ π ππππ π‘πππ‘πππ πΆππππππ‘πππ π·ππ‘π
πππ ππππβ
π΄ππ‘π’ππ π·ππ‘π πππ ππππ
Chapter 5 Results and Discussion
64
Wor
k O
rder
App
rova
l Total Number
of Work Orders
Work order creation date β (query start date, query end date)
ππ’π ππππ ππππππ π€βπππ ππ_ππ¦ππ β²ππππ π‘π ππππππ‘β²
Total Number of Approved Work Orders
Work order creation date β (query start date, query end date)
ππ’π ππππ ππππππ π€βπππ ππ β²ππππ π‘π ππππππ‘β² &
β²πππ ππ ππππππ‘πππ ππππππβ²
Total Number of Unapproved Work Orders
Work order creation date β (query start date, query end date)
ππ’π ππππ ππππππ π€βπππ ππ β²ππππ π‘π ππππππ‘β² &
β²πππ ππππππ‘πππ ππππππβ²
Work Order Approval Ratio
Work order creation date β (query start date, query end date)
ππππ ππππππ π‘π ππ π΄πππππ£ππππ’ππππ ππ πππππππ ππππ ππππππ πΆππππ‘ππ
One-time Approved Work
Order Ratio
Work order creation date β (query start date, query end date)
πππ‘ππ ππ’ππππ ππ π΄πππππ£ππ ππππ ππππππ πππ‘ππ ππ’ππππ ππ ππππ ππππππ
Average time lag for
Reporting and Approving
Work Orders
Work order creation date β (query start date, query end date)
ππ’π ππππ πππππ π΄πππππ£ππ π·ππ‘π β ππππ πππππ π πππππ‘ π·ππ‘π
π€βπππ ππ_ππ¦ππ β²π πππππ‘ π πππ’ππππ πππ‘ππ ππ’ππππ ππ π΄πππππ£ππ ππππ ππππππ
Mai
nten
ance
Exe
cuti
on
Qua
ntit
y R
elat
ed
Number of Planned Work
Orders Completed
Work order completion date β (query start date, query end date)
πΆππ’ππ‘ π ππππ π‘ππππ ππππ πππππ πβπππ β²ππ_ππ¦ππ ππ βππππβ²
Number of Unplanned
Work Orders Completed
Work order completion date β (query start date, query end date)
πΆππ’ππ‘ π ππππ π‘ππππ ππππ πππππ πβπππ ππ_ππ¦ππ ππ βπ’ππππππππβ
Number of Work Orders
Completed per Shift
Work order completion date β (query start date, query end date)
ππ’ππππ ππ ππππ ππππππ πππππππππ ππ ππβπππ’πππ
πππ‘ππ ππ’ππππ ππ ππβπππ’πππ ππππ ππππππ
β 100
Work Order Resolution Rate
Work order completion date β (query start date, query end date)
ππ’ππππ ππ ππππ ππππππ πππππππππ ππ ππβπππ’πππ
πππ‘ππ ππ’ππππ ππ ππβπππ’πππ ππππ ππππππ
β 100
Tim
e R
elat
ed Average Work
Order Time
Work order completion date β (query start date, query end date)
ππ’π πΆππππππ‘ππ πππππ‘ππ ππππ πππππ πΈπ₯πππ’π‘πππ ππππ
πΆππ’ππ‘ πΆππππππ‘ππ πππππ‘ππ ππππ πππππ
Average Waiting Time for Personnel
Work order completion date β (query start date, query end date)
ππ’π πΆππππππ‘ππ πππππ‘ππ ππππ πππππ π€ππ‘β ππ‘πππ ππ πππππ ππππ πΆππ’ππ‘ πΆππππππ‘ππ πππ ππ‘ππ ππππ πππππ
KPI framework for maintenance management through eMaintenance
65
Average Waiting Time
for Spare Parts
Work order completion date β (query start date, query end date)
ππ’π πππππ ππ πππππ πππππβπππ πΆππππππ‘ππ πππ
ππ‘ππ ππππ πππππ πππππ ππππ‘π ππππ ππππ πππππ
πΆππ’ππ‘ πΆππππππ‘ππ πππππ‘ππ ππππ πππππ πππππ ππππ‘π ππππ
ππππ πππππ
Personnel Waiting Time
Ratio
Work order completion date β (query start date, query end date)
π΄π£πππππ ππππ‘πππ ππππ πππ ππππ πππππ π΄π£πππππ ππππ πππππ ππππ
Spare Parts Waiting Time
Ratio
Work order completion date β (query start date, query end date)
π΄π£πππππ ππππ‘πππ ππππ πππ πππππ ππππ‘π π΄π£πππππ ππππ πππππ ππππ
Average Maintenance Outage Time
Work order completion date β (query start date, query end date)
ππ’π πΈπ₯πππ’π‘πππ πππππβπππ ππ₯ππ π‘ πππππππ‘ππ ππππ
π π‘ππ ππ ππππ π€πππ πππππ πΆππ’ππ‘ πΆππππππ‘ππ ππ‘πππ‘ππ‘ππ ππ ππππ ππππ πππππ
Average Waiting Time of
Personnel during
Shutdown
Work order completion date β (query start date, query end date)
ππ’π ππ‘πππ ππ πππππ πππππβπππ ππ₯ππ π‘ πππππππ‘ππ π π‘πππ‘
ππ ππππ π€πππ πππππ πΆππ’ππ‘ πΆππππππ‘ππ ππ‘πππ‘ ππ
ππππ ππππ πππππ
Average Waiting Time
for Spare Parts during
Shutdown
Work order completion date β (query start date, query end date)
ππ’π πππππ ππ πππππ πππππβπππ πππππππ‘ππ π π‘ππ ππππ
π€ππ‘β π ππππ ππππ‘π ππππ π€πππ ππππππΆππ’ππ‘ πΆππππππ‘ππ ππ‘ππ πΏπππ
πππ‘β πππππ ππππ‘π ππππ ππππ πππππ
Average Waiting Time of
Personnel during
Shutdown Ratio
Work order completion date β (query start date, query end date)
π΄π£πππππ ππππ‘πππ ππππ πππ ππππ πππππ ππ’ππππ πβπ’π‘πππ€π
π΄π£πππππ πππππ‘ππππππ ππ’π‘πππ ππππ
Average Waiting Time
for Spare Parts during
Shutdown Ratio
Work order completion date β (query start date, query end date)
π΄π£πππππ ππππ‘πππ ππππ πππ πππππ ππππ‘π ππ’ππππ πβπ’π‘πππ€π
π΄π£πππππ πππππ‘ππππππ ππ’π‘πππ ππππ
Estimated Time vs. Actual Time
Work order completion date β (query start date, query end date)
π΄π£πππππ πππππππ πΈπ₯πππ’π‘πππ πππππ΄π£πππππ ππππ πππππ ππππ
Res
ourc
e R
elat
ed
Total Number of Internal
Labour Hours
Work order completion date β (query start date, query end date)
ππ’π π ππππ π‘ππππ πΏππππ’π π»ππ’ππ
Average Internal Labour
Hours Used
Work order completion date β (query start date, query end date)
ππ’π π ππππ π‘ππππ πΏππππ’π π»ππ’ππ πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ
Total Number of External
Labour Hours
Work order completion date β (query start date, query end date)
ππ’π π ππππ π‘ππππ πΏππππ’π π»ππ’ππ
Chapter 5 Results and Discussion
66
Average External
Labour Hours Used
Work order completion date β (query start date, query end date)
ππ’π π ππππ π‘ππππ πΏππππ’π π»ππ’ππ πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ
Number of Materials Used
Work order completion date β (query start date, query end date)
ππ’π ππ’ππππ ππ π ππππ π‘ππππ πππππ ππππ‘π
Average Material Used
Work order completion date β (query start date, query end date)
ππ’π ππ’ππππ ππ π ππππ π‘ππππ πππππ ππππ‘π πΆππ’ππ‘ πΆππππππ‘ππ ππππ πππππ
Cost
Rel
ated
Total Cost of External Human
Resources Used
Work order registration date β (query start date, query termination date)
ππ’π π»ππ’πππ¦ π ππ‘π β π ππππ π‘πππ‘πππ ππ πΉππππππ πΏππππ’π π»ππ’ππ
Average External Human
Resources Costs
Work order registration date β (query start date, query termination date)
πππ‘ππ πΆππ π‘ ππ πΈπ₯π‘πππππ π»π’πππ π ππ ππ’ππππ ππ πππΆππ’ππ‘ πΆππππππ‘ππ ππππ πππππ
πβπππ π€πππ πππ‘πππππ¦ βππ₯π‘πππππβ
Total Cost of Materials Used
Work order registration date β (query start date, query termination date)
ππ’π πππππ ππππ‘π ππ’πππ‘ππ‘π¦ β πππππ ππππ‘π πππππ
Average Cost of Materials Used
Work order registration date β (query start date, query termination date)
πππ‘ππ πΆππ π‘ ππ πππ‘πππππ ππ πππΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ
External Labour Costs
Ratio
Work order registration date β (query start date, query termination date)
πππ‘ππ πΆππ π‘ ππ πΈπ₯π‘πππππ π»π’πππ π ππ ππ’ππππ ππ ππ πππ‘ππ πΆππ π‘ ππ
πΈπ₯π‘πππππ π»π’πππ π ππ ππ’ππππ ππ ππ πππ‘ππ πΆππ π‘ ππ πππ‘πππππ ππ ππ
Actual Materials Cost
Ratio
Work order registration date β (query start date, query termination date)
πππ‘ππ πΆππ π‘ ππ πππ‘πππππ ππ πππππ‘ππ πΆππ π‘ ππ
πΈπ₯π‘πππππ π»π’πππ π ππ ππ’ππππ ππ ππ πππ‘ππ πΆππ π‘ ππ πππ‘πππππ ππ ππ
Maintenance Cost per Asset
Work order registration date β (query start date, query termination date)
ππ’π π·ππ π‘ππππ‘ ππ π ππ‘ πππππ ππππ‘π ππ’πππ‘ππ‘π¦ β πππππ ππππ‘π πππππ )
KPI framework for maintenance management through eMaintenance
67
Mai
nten
ance
Ass
essm
ent
Qua
lity
Number of Completed
Work Orders Approved
Work order creation date β (query start date, query end date)
πΆππ’ππ‘ ππππ πππππ πβπππ ππ‘ππ‘π’π β²πππππππ‘π πππ ππ_ππ¦ππ β²ππππππ£ππβ²
Work Order Approval Ratio
Work order creation date β (query start date, query end date)
πΆππ’ππ‘ ππππ πππππ πβπππ ππ β²ππππ’πππ ππππππ£ππβ²
πΆππ’ππ‘ ππ’ππππ ππ ππππ ππππππ
One-Time Pass Internal
Completion Rate
Work order creation date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ ππππ ππππππ πβπππ ππ
β²πππππππ‘ππ πππ ππππππ£ππβ² βππππππ£ππ ππππβ πΆππ’ππ‘ ππ’ππππ ππ ππππ ππππππ π€βπππ π€πππ ππππ’π β²πππ‘πππππβ²
One-Time Pass External
Completion Rate
Work order creation date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ ππππ ππππππ π€βπππ ππ β²πππππππ‘ππ πππ ππππππ£ππβ² βππππππ£ππ ππππβ
πΆππ’ππ‘ ππ’ππππ ππ ππππ ππππππ π€βπππ π€πππ ππππ’π β²ππ₯π‘πππππβ²
Planning Compliance
Work order creation date β (query start date, query end date)
πππππππ πππ π»ππ’ππ πΆππππππ‘πππππ‘ππ ππππππ¦ πππππππ πππ π»ππ’ππ
β 100
Effe
ctiv
enes
s
Internal Work Completion
Rate
Planned work order ompletion date β (query start date, query termination date)
ππ’π πΆππππππ‘ππ ππππ ππππππ πΆππ’ππ‘ ππππ ππππππ πβπππ π€πππππππ’π
β²πΌππ‘πππππβ²
Outsourced Work
Completion Rate
Planned work order completion date β (query start date, query termination date)
ππ’π πΆππππππ‘ππ ππππ ππππππ πΆππ’ππ‘ ππππ ππππππ
πβππππ€πππ ππππ’π β²ππ₯π‘πππππβ²
Internal Work Delay Rate
Work order registration date β (query start date, query termination date)
ππ’π ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ πβπππ πππππ π‘πππ‘πππ πππ‘π
ππππ πππππππ‘πππ πππ‘πβ²πΆππ’ππ‘ πΆππππππ‘ππ ππππ πππππ ππ’ππππ
Internal Work Average Delay
Period
Work order registration date β (query start date, query termination date)
ππ’π π ππππ π‘πππ‘πππ π·ππ‘π β
πππππππ πΆππππππ‘πππ π·ππ‘ππβπππ πππππ π‘πππ‘πππ πππ‘π
πππππππ πππππππ‘πππ πππ‘πβ² πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ
πβπππ πππππ π‘πππ‘πππ πππ‘π πππππππ πππππππ‘πππ πππ‘πβ²
External Work Delay Rate
Work order registration date β (query start date, query termination date)
ππ’π ππ’ππππ ππ πΆππππππ‘ππ ππππ ππππππ
πβπππ πππππ π‘πππ‘πππ πππ‘π ππππ πππππππ‘πππ πππ‘πβ²
πΆππ’ππ‘ πΆππππππ‘ππ ππππ πππππ ππ’ππππ
External Work Average Delay
Period
Ticket registration date β (inquiry start date, inquiry termination date)
ππ’π π ππππ π‘πππ‘πππ π·ππ‘π β πππππππ πΆππππππ‘πππ π·ππ‘π
πβπππ πππππ π‘πππ‘πππ πππ‘π πππππππ πππππππ‘πππ πππ‘πβ²
πΆππ’ππ‘ ππ’ππππ ππ πΆππππππ‘ππ ππππππ πβπππ πππππ π‘πππ‘πππ πππ‘π
ππππ πππππππ‘πππ πππ‘πβ²
Chapter 5 Results and Discussion
68
Internal Average
Execution Time Deviation Ratio
Work order creation date (date of inquiry, date of inquiry termination)
πΌππ‘πππππ πππππππ π΄π£πππππ π΄ππ‘π’ππ πΈπ₯πππ’π‘πππ ππππ
β
πΌππ‘πππππ πππππππ π΄π£πππππ πππππππ πΈπ₯πππ’π‘πππ ππππ πΌππ‘πππππ πππππππ π΄π£πππππ πππππππ πΈπ₯πππ’π‘πππ ππππ
External Committee
Execution Time Deviation Ratio
Work order creation date (date of inquiry, date of inquiry termination)
πΈπ₯π‘πππππ πππππππ π΄π£πππππ π΄ππ‘π’ππ πΈπ₯πππ’π‘πππ ππππ
β
πΈπ₯π‘πππππ πππππππ π΄π£πππππ πππππππ πΈπ₯πππ’π‘πππ ππππ
πΈπ₯π‘πππππ πππππππ π΄π£πππππ πππππππ πΈπ₯πππ’π‘πππ ππππ
Internal Man-Hour Difference
Ratio
Work order creation date (date of inquiry, date of inquiry termination)
ππ’π π ππππ π‘πππ‘πππ πΏππππ’π ππππ ππ’π πππππππ πΏππππ’π ππππππ’π πππππππ πΏππππ’π ππππ
Internal Average Man-
Hour Difference Ratio
Work order creation date (date of inquiry, date of inquiry termination)
πΌππ‘πππππ π΄π£πππππ πΏππππ’π πππππΌππ‘πππππ π΄π£πππππ ππππ πΏππππ’π ππππ πΌππ‘πππππ π΄π£πππππ ππππ πΏππππ’π ππππ
External Man-Hour Difference
Ratio
Work order creation date (date of inquiry, date of inquiry termination)
ππ’π π ππππ π‘πππ‘πππ πΏππππ’π ππππ ππ’π πππππππ πΏππππ’π ππππ ππ’π πππππππ πΏππππ’π ππππ
External Average Man-
Hour Difference Ratio
Work order creation date (date of inquiry, date of inquiry termination)
πΈπ₯π‘πππππ π΄π£πππππ πΏππππ’π πππππΈπ₯π‘πππππ π΄π£πππππ ππππ πΏππππ’π πππππΈπ₯π‘πππππ π΄π£πππππ ππππ πΏππππ’π ππππ
Materials Difference
Ratio
Work order creation date (date of inquiry, date of inquiry termination)
ππ’π π ππππ π‘ππππ πππππ ππππ‘π ππ’π ππβπππ’πππ πππππ ππππ‘ππ’π ππβπππ’πππ πππππ ππππ‘
Average Materials Difference
Ratio
Work order creation date (date of inquiry, date of inquiry termination)
π΄π£πππππ π ππππ π‘ππππ πππππ ππππ‘π π΄π£πππππ ππβπππ’πππ πππππ ππππ‘π π΄π£πππππ ππβπππ’πππ πππππ ππππ‘π
5.2.3 KPIimplementationformaintenanceresourcemanagement
This section presents the results of KPI implementation for maintenance resource management; it provides data sources, time definitions, and general formulas for the related KPIs. These are shown in Table 5.2.3.
KPI framework for maintenance management through eMaintenance
69
Table 5.2.3 Implementation in an eMaintenance environment for maintenance resource management
LevelName Timeline GeneralFormula
3 4
Spar
e Pa
rts
Man
agem
ent
Inve
ntor
y M
anag
emen
t
Average Spare Part Quantity
Spare parts stock date (query start date, query end date)
πππππππ ππ‘πππ πΈπππππ ππ‘πππ 2
Spare Part Capital Utilization
equipment ledger date(query start date, query end date)
πππππ ππππ‘π πΌππ£πππ‘πππ¦ πΉπ’πππ ππ’π πΈππ’ππππππ‘ ππ’ππβππ π πππππ
Spare Parts Capital Replacement Rate
equipment ledger date(query start date, query end date)
πππππ ππππ‘π πΌππ£πππ‘πππ¦ πΉπ’πππ ππ’π πΈππ’ππππππ‘ π ππππππππππ‘ πΆππ π‘
Spare Part Consumption per
Thousand Sek Output
Work order registration date β (query start date, query end date)
ππ’π πππ‘ππ πΆππ π‘ ππ πππππ ππππ‘π πΆπππ π’πππ‘ππππππ‘ππ ππ’π‘ππ’π‘ ππππ’π πππ 1000 πππ ππ’π‘ππ’π‘
Spare Part Turnover Rate
Work order registration date β (query start date, query end date)
ππ’π πππ‘ππ πΆππ π‘ ππ πππππ ππππ‘π πΆπππ π’πππ‘πππ π΄π£πππππ πππππ ππππ‘π πΌππ£πππ‘πππ¦ πΉπ’πππ
Spare Part Turnover Period
Work order registration date β (query start date, query end date)
π΄π£πππππ πππππ ππππ‘π πΌππ£πππ‘πππ¦ πΉπ’πππ ππ’π πππ‘ππ πΆππ π‘ ππ πππππ ππππ‘π πΆπππ π’πππ‘πππ
β 365
Slow Moving Inventory Ratio
equipment ledger date(query start date, query end date)
ππ’ππππ ππ πππππ ππππ‘π πππ‘ ππ ππ πππ‘ππ ππ’ππππ ππ πππππ
Out
sour
cing
Man
agem
ent
Cont
ract
or S
tati
stic
s
Number of Outsourced Equipment
Breakdowns
Work supplier list date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ π ππππ π‘ππππ ππ‘πππ πβπππ ππ πππππ‘ππππππ ππππ πππππ
& βππ’π‘π ππ’ππππβ
Number of Outsourced
Maintenance Personnel
Work supplier list date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΈπππππ¦πππ πβπππ ππ πππππ‘ππππππ ππππ πππππ
& βππ’π‘π ππ’ππππβ
External Maintenance Cost
Ratio
Work supplier list date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΈπ₯π‘πππππ ππππ πππππ β π ππ‘π ππ ππππ π·πππ
πππ‘ππ πππππ‘ππππππ πΆππ π‘β 100
Hum
an R
esou
rces
Man
agem
ent
Skill
s M
anag
emen
t
Total Number of Maintenance
Operators
Work supplier list date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΈπππππ¦πππ πβπππ ππ πππππ‘ππππππ ππππ πππππ
& β²ππππππ‘ππβ²
Total Number of Maintenance
Engineers
Work supplier list date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΈπππππ¦πππ π€βπππ ππ πππππ‘ππππππ ππππ πππππ
& β²ππππππππβ²
Number of Multi-Skilled Maintenance
Personnel
Work supplier list date β (query start date, query
πΆππ’ππ‘ ππ’ππππ ππ πΈπππππ¦πππ πβπππ ππ πππππ‘ππππππ ππππ πππππ
& β²ππ’ππ‘π π ππππβ²
Chapter 5 Results and Discussion
70
end date)
Maintenance Operator Rate
Work supplier list date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΈπππππ¦πππ πβπππ ππ β²πππππ‘ππππππ ππππ πππππβ²
β²ππππππ‘ππβ²πΆππ’ππ‘ ππ’ππππ ππ πΈπππππ¦πππ
β 100
Maintenance Engineer Rate
Work supplier list date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΈπππππ¦πππ πβπππ ππ β²πππππ‘ππππππ ππππ πππππβ²
β²ππππππππβ² πΆππ’ππ‘ ππ’ππππ ππ πΈπππππ¦πππ
β 100
Multi-Skilled Maintenance
Personnel Rate
Work supplier list date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΈπππππ¦πππ πβπππ ππ πππππ‘ππππππ ππππ πππππ
β²ππ’ππ‘π π ππππβ²πΆππ’ππ‘ ππ’ππππ ππ πΈπππππ¦πππ
β 100
Wor
k Lo
ad M
anag
emen
t
Average Number of Work Orders Created
per Person
Work order creation date β (query start date, query end date)
ππ’π ππ’ππππ ππ π€πππ ππππππ πΆππ’ππ‘ ππ’ππππ ππ ππππππ¦πππ
πβπππ ππ βπππ ππππ ππππ πππ π€πππ πππππ πππππ‘πππβ
Average Number of Work Orders
Executed per Person
Work order creation date β (query start date, query end date)
ππ’π ππ’ππππ ππ ππππ πΆππ’ππ‘ ππ’ππππ ππ πΈπππππ¦πππ
πβπππ ππ βπππ ππππ ππππ πππ π€πππ πππππ ππ₯πππ’π‘πππβ
Average Daily Workload per
Person
Work order creation date β (query start date, query end date)
ππ’π π ππππ π‘ππππ π»ππ’ππ πΆππ’ππ‘ ππ’ππππ ππ πΈπππππ¦πππ
πβπππ ππ βπππ ππππ ππππ πππ π€πππ πππππ ππ₯πππ’π‘πππβ β
ππ’ππππ ππ π·ππ¦π ππ’ππππ πΌπππ’πππ¦
Tra
inin
g M
anag
emen
t
Average Annual Training Hours per
Maintenance Operator
Work order creation date β (query start date, query end date)
ππ’π π ππππ π‘ππππ π»ππ’ππ πΆππ’ππ‘ ππ’ππππ ππ πΈπππππ¦πππ
πβπππ ππ β²πππππ‘ππππππ ππππ πππππβ² β²ππππππ‘ππβ²
β 365
Average Annual Training Hours per
Maintenance Engineers
Work order creation date β (query start date, query end date)
ππ’π π ππππ π‘ππππ π»ππ’ππ πΆππ’ππ‘ ππ’ππππ ππ πΈπππππ¦πππ
πβπππ ππ πππππ‘ππππππ ππππ πππππ β²ππππππππβ²
β 365
Average Annual
Training Hours per Multi-Skilled Maintenance
Engineers
Work order creation date β (query start date, query end date)
ππ’π π ππππ π‘ππππ π»ππ’ππ πΆππ’ππ‘ ππ’ππππ ππ πΈπππππ¦πππ
πβπππ ππ πππππ‘ππππππ ππππ πππππ β²ππ’ππ‘π π ππππππβ²
β 365
Com
pete
nce
Dev
elop
men
t
Number of New Senior Maintenance
Engineers
Work supplier list date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΈπππππ¦πππ πβπππ ππ πππππ‘ππππππ ππππ πππππ
& β²ππππππ‘ππβ² & πππ€ π πππ βπππππ‘ππππππ ππππππππβ
Percentage of New Senior Maintenance
Engineers
Work supplier list date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΈπππππ¦πππ πβπππ ππ πππππ‘ππππππ ππππ πππππ
& β²ππππππ‘ππβ² & πππ€ ππππ βπππππ‘ππππππ ππππππππβ β 100
Number of New Multi-Skilled Maintenance
Engineers
Work supplier list date β (query start date, query
πΆππ’ππ‘ ππ’ππππ ππ πΈπππππ¦πππ πβπππ ππ πππππ‘ππππππ ππππ πππππ
& β²πππππ‘ππππππ ππππππππβ² & πππ€ ππππ βππ’ππ‘π
KPI framework for maintenance management through eMaintenance
71
end date) π ππππππ πππππ‘ππππππ ππππππππβ
Percentage of New Multi-Skilled Maintenance
Engineers
Work supplier list date β (query start date, query end date)
πΆππ’ππ‘ ππ’ππππ ππ πΈπππππ¦πππ πβπππ ππ πππππ‘ππππππ ππππ πππππ
& β²πππππ‘ππππππ ππππππππβ² πππ πππ€ ππππ βππ’ππ‘π
π ππππππ πππππ‘ππππππ ππππππππβ β 100
Note that the results from this study can be applied by the studied company. The results will guide their implementation of the KPIs in an eMaintenance environment.
5.3 ResultsanddiscussionrelatedtoRQ3
RQ3: How can the KPIs be assessed using novel approaches?
The third research question is answered by developing approaches to assess the technical KPIs in Paper B and Paper C and to assess the soft KPIs in Section 5.3.3 of this thesis.
In Paper B and Paper C, system availability is selected as a KPI to illustrate the proposed novel approaches.
5.3.1 AssessmentoftechnicalKPIs
This study proposes a new approach to system availability assessment: a parametric Bayesian approach using MCMC, an approach that takes advantage of both analytical and simulation methods. By using this approach, Mean Time to Failure (MTTF) and Mean Time to Repair (MTTR) are treated as distributions instead of being βaveragedβ, which better reflects reality and compensates for the limitations of simulation data sample size. To demonstrate the approach, the paper considers a case study of a balling drum system in a mining company. In this system, MTTF and MTTR are determined in a Bayesian Weibull model and a Bayesian lognormal model respectively. The results show that the proposed approach can integrate the analytical and simulation methods to assess system availability and could be applied to other technical problems in asset management (e.g., other industries, other systems).
5.3.1.1BayesianWeibullmodelforTTF
Suppose the Time to Failure (TTF) data t t , t , β― , t for n individuals are i. i. d., and each corresponds to a 2-parameter Weibull distribution W Ξ±, Ξ³ , where Ξ± 0 and Ξ³ 0. Then, the p. d. f. is f t |Ξ±, Ξ³ Ξ±Ξ³t exp Ξ³t , while the c. d. f. is F t |Ξ±, Ξ³ 1exp Ξ³t . The reliability function is R t |Ξ±, Ξ³ exp Ξ³t .
Denote the observed data set as D0 n, t . Therefore, the likelihood function for Ξ± and Ξ³ is
πΏ πΌ, πΎ|π· π π‘ |πΌ, πΎ πΌπΎπ‘ ππ₯π πΎπ‘ 5.3.1
Chapter 5 Results and Discussion
72
In this study, we assume Ξ± to be a gamma distribution (Kuo, 1985), denoted by G a , b as its prior distribution, written as Ο Ξ± |a , b ; we assume Ξ³ to be a gamma distribution denoted by G c , d as its prior distribution, written as Ο Ξ³|c , d . This means
π πΌ |π , π β πΌ ππ₯π π πΌ (5.3.2)
π πΎ|π , π β πΎ ππ₯π π πΎ (5.3.3)
Therefore, the joint posterior distribution can be obtained according to equations (5.3.1) to (5.3.3) as
π πΌ, πΎ|π· β πΏ πΌ, πΎ|π· π πΌ |π , π π πΎ|π , π , 5.3.4
and the parametersβ full conditional distribution with Gibbs sampling can be written as
π πΌπ|πΌ π , πΎ, π·0 β πΏ πΌ, πΎ|π·0 πΌπ0 1ππ₯π π0πΌ 5.3.5
π πΎπ|πΌ, πΎ π , π·0 β πΏ πΌ, πΎ|π·0 πΎπ0 1ππ₯π π0πΎ 5.3.6
5.3.1.2BayesianLognormalmodelforTTR
Suppose the Time to Repair (TTF) data t t , t , β― , t for n individuals are i. i. d., and each ln t corresponds to a normal distribution, N ΞΌ, Ο . We can get tiβs lognormal distribution with parameters ΞΌ and Ο2. Then, the p. d. f. and c. d. f. are given by equation (5.3.7) and equation (5.3.8):
π π‘ |π, π1
β2πππ‘ππ₯π
12π
ππ π‘ π 5.3.7
πΉ π‘ |π, π Ξ¦ππ π‘ π
π 5.3.8
Denote the observed data set as D0 n, t . Therefore, according to equation (5.3.7), the likelihood function for ΞΌ and Ο becomes
πΏ π, π|π· π π‘ |π, π 5.3.9
KPI framework for maintenance management through eMaintenance
73
In this study, we assume ΞΌ to be a normal distribution denoted by N e , f as its prior distribution, written as Ο ΞΌ|e , f ; we assume Ο to be a gamma distribution denoted by G g , h as its prior distribution, written as Ο Ο|g , h . This means
π π|π , π β π ππ₯ππ2
π π 5.3.10
π π|π , β β π ππ₯π β π (5.3.11)
Therefore, the joint posterior distribution can be obtained according to equations (5.3.9) to (5.3.11) as
π π, π|π· β πΏ π, π|π· π π |π , π π π|π , β 5.3.12
Then, the parametersβ full conditional distribution with Gibbs sampling can be written as
π π |π , π, π· β πΏ π, π|π· π0
12ππ₯π
π0
2π π0
2 5.3.13
Ο π |π, π , π· β πΏ π, π|π· π ππ₯π β π 5.3.14
5.3.1.3Resultsofthecasestudy
In this case study, a three-chain Markov chain is constructed for each MCMC simulation. A burn-in of 1000 samples is used, with an additional 10,000 Gibbs samples for each Markov chain. Vague prior distributions are adopted as follows:
For Bayesian Weibull model using TTF data:
πΌ~πΊ 0.0001, 0.0001 , πΎ~πΊ 0.0001, 0.0001 ;
For Bayesian lognormal model using TTR data:
π~π 0, 0.0001 , π~πΊ 0.0001, 0.0001 .
Using the convergence diagnostics (i.e. checking dynamic traces in Markov chains, determining time series and Gelman-Rubin-Brooks (GRB) statistics, and comparing Monte Carlo error (MC error) with standard deviation (SD)) (Lin, 2014), we consider the following posterior distribution summaries for our models (see Table 5.3.1 and Table 5.3.2), including the parametersβ posterior distribution mean, SD, MC error, and 95% highest posterior distribution density (HPD) interval.
Chapter 5 Results and Discussion
74
Table 5.3.1 Posterior statistics in Bayesian Weibull model for TTF
Ballingdrum Parameter Mean SD MCerror 95%HPDinterval
1 πΌ 0.5409 0.0231 4.288E-4 (0.4964, 0.5867) πΎ 0.0928 0.0120 2.235E-4 (0.0712, 0.1178)
2 πΌ 0.5747 0.0288 6.289E-4 (0.5195, 0.6324) πΎ 0.0642 0.0109 2.334E-4 (0.0451, 0.0876)
3 πΌ 0.5975 0.0251 5.004E-4 (0.5974, 0.6481) πΎ 0.0712 0.0098 1.942E-4 (0.0707, 0.0922)
4 πΌ 0.5745 0.0245 4.885E-4 (0.5272, 0.6236) πΎ 0.0750 0.0104 2.028E-4 (0.0564, 0.0970)
5 πΌ 0.5560 0.0216 4.135E-4 (0.5558, 0.5988) πΎ 0.0958 0.0112 2.158E-4 (0.0952, 0.1196)
Table 5.3.2 Posterior statistics in Bayesian lognormal model for TTR
Ballingdrum Parameter Mean SD MCerror 95%HPDinterval
1 π -0.1842 0.1107 6.730E-4 (-0.4015, 0.0342) π 0.2270 0.0169 9.565E-5 ( 0.1951,0.2615 )
2 π -0.0075 0.1424 8.504E-4 (-0.2845,0.2697) π 0.1861 0.0161 9.140E-5 ( 0.1556, 0.2193)
3 π -0.4574 0.1134 6.540E-4 (-0.4578, -0.2354) π 0.2196 0.0164 9.621E-5 ( 0.2191, 0.2533 )
4 π -0.3540 0.1145 7.052E-4 (-0.5787, -0.1297) π 0.2184 0.0166 9.845E-5 ( 0.1871, 0.2523 )
5 π -0.3484 0.1023 6.265E-4 (-0.3486, -0.1488) π 0.2195 0.0148 8.614E-5 ( 0.2189, 0.2495 )
Using the results from Table 5.3.1 and Table 5.3.2, we calculate the availability of individual balling drums in Table 5.3.3, where MTTF = E f t |Ξ±, Ξ³ , and MTTR = E f t |ΞΌ, Ο .
Table 5.3.3 Statistics of individual availability
BallingdrumMTTF MTTR Availability
Mean 95% HPD interval Mean 95% HPD interval Mean 95% HPD interval 1 145.0 (118.1, 178.0) 7.779 (5.284, 11.58) 0.9487 (0.9229, 0.9665) 2 196.4 (157.7, 256.0) 15.48 (8.927, 26.60) 0.9265 (0.8766, 0.9582) 3 128.7 (127.9, 155.0) 6.381 (6.194, 9.622) 0.9525 (0.9538, 0.9693) 4 148.5 (122.5, 180.3) 7.178 (4.755, 10.86) 0.9536 (0.9291, 0.9702) 5 115.8 (115.1, 139.0) 7.083 (6.926, 10.22) 0.9420 (0.9433, 0.9610)
According to the assumption that it is treated as a parallel system, the system availability of the five balling drums is
π΄π π¦π π‘ππ 1 1 π΄π
5
π 1
0.99
KPI framework for maintenance management through eMaintenance
75
5.3.1.4Discussionofthecasestudy
Compared to the traditional method of assessing availability, the proposed approach extends the method to equation (5.3.15), where
π΄πΈ π πππΉ
πΈ π πππΉ πΈ π πππ
πΈ π π‘ |πΌ, πΎπΈ π π‘ |πΌ, πΎ πΈ π π‘ |π, π
5.3.15
Equation (5.3.15) shows the flexibility of assessing availability according to reality. For one thing, the parametric Bayesian models using MCMC make the calculation of posteriors more feasible. More importantly, however, parametric Bayesian models can be applied to predict TTF, TTR, and system availability in the future.
In this study, since the five balling drums are relatively new, the gamma distributions and normal distributions are selected as vague priors due to lack of prior information. This could be improved with more historical data/experience.
The system configurations could be extended to other more complex architectures (series, k-out-of-n, stand-by, multi-state, or mixed).
The data analysis reveals that for TTF data, the shape parameter for the Weibull distribution is less than 1. The TTFs have a decreasing trend (as in an early stage of the bathtub curve) which is not suitable for the experience of mechanical equipment. The TTF data include not only corrective maintenance but also preventive maintenance. In this case study, a high percentage of TTF work orders are for preventive maintenance. The decreasing trends also indicate that a possible way to improve TTF is to improve the preventive maintenance plan.
The three stages (8 steps) presented in section 3.4.1 can set within a PDCA cycle. Steps 2 to 4 can be treated as the Plan stage; Step 5 and Step 6 as the Do and Check stages respectively, and Step 7 as the Action stage. The outputs from Step 7 could become input for Step 2 for the next calculation period. Thus, the eight steps follow the PDCA cycle, and the results could be continuously improved.
5.3.2 AssessmentandconnectionsoftechnicalandsoftKPIs
This study proposes a Bayesian approach to evaluate system availability. In this approach: 1) Mean Time to Failure (MTTF) and Mean Time to Repair (MTTR) are treated as distributions instead of being βaveragedβ to better describe real scenarios and overcome the limitations of data sample size; 2) Markov Chain Monte Carlo (MCMC) simulations are applied to take advantage of analytical and simulation methods; 3) a threshold is set for Time to Failure (TTR) data and Time to Repair (TTR) data, and new datasets with right-censored data are created to reveal the connections between technical and soft KPIs. To demonstrate the approach, the paper considers a case study of a balling drum system in a mining company. In this system, MTTF and MTTR are determined by a Bayesian Weibull model and a Bayesian lognormal model respectively.
Chapter 5 Results and Discussion
76
The results show that the proposed approach can integrate the analytical and simulation methods to assess system availability and could be applied to other technical problems in asset management (e.g., other industries, other systems). By comparing the results with and without considering the threshold for censoring data, we show the threshold can be used as a monitoring line for continuous improvement in the investigated mining company.
5.3.2.1Likelihoodconstructionforrightβcensoreddata
In practice, lifetime data are usually incomplete, and only a portion of the individual lifetimes of assets are known. Right-censored data are often called Type I censoring in the literature; the corresponding likelihood construction problem has been extensively studied. The right-censored data of this study are illustrated in Figure 3.4 and Figure 3.5.
Suppose there are n individuals whose lifetimes and censoring times are independent. The i th individual has life time T and censoring time L . The T s are assumed to have probability density function f t and reliability function R t . The exact lifetime T of an individual will be observed only if T L . The lifetime data involving right censoring can be conveniently represented by n pairs of random variables t , v , where tmin T , L and v 1 if T L and v 0if T L . That is, v indicates whether the lifetime T is censored or not. The likelihood function is deduced as
πΏ π‘ π π‘ π π‘ 5.3.16
5.3.2.2BayesianmodellingforTTFwithrightβcensoreddata
Suppose the Time to Failure (TTF) data t t , t , β― , t for n individuals are i. i. d., and each corresponds to a 2-parameter Weibull distribution W Ξ±, Ξ³ , where Ξ± 0 and Ξ³ 0. Then, the p. d. f. is f t |Ξ±, Ξ³ Ξ±Ξ³t exp Ξ³t , while the c. d. f. is F t |Ξ±, Ξ³ 1exp Ξ³t , and the reliability function is R t |Ξ±, Ξ³ exp Ξ³t .
Let v v , v , β¦ , v indicate whether the lifetime is right-censored or not, and let the observed dataset for the study be denoted as D , where D n, t, v , following equation (5.3.16). Therefore, the likelihood function for Ξ± and Ξ³ is
πΏ πΌ, πΎ|π· πΌβ ππ₯π π£ ππ πΎ π£ πΌ 1 ππ π‘ πΎπ‘ 5.3.17
In this study, we take Ξ± and Ξ³ to be independent. Furthermore, we assume Ξ± to be a gamma distribution, denoted by G a , b as its prior distribution, written as Ο Ξ± |a , b , and we assume Ξ³ to be a gamma distribution denoted by G c , d as its prior distribution, written as Ο Ξ³|c , d . This means
KPI framework for maintenance management through eMaintenance
77
π πΌ |π , π β πΌ ππ₯π π πΌ (5.3.18)
π πΎ|π , π β πΎ ππ₯π π πΎ (5.3.19)
Therefore, the joint posterior distribution can be obtained according to equations (5.3.17) to (5.3.19) as
π πΌ, πΎ|π· β πΏ πΌ, πΎ|π· π πΌ |π , π π πΎ|π , π 5.3.20
The parametersβ full conditional distribution with Gibbs sampling can be written as
π πΌπ|πΌ π , πΎ, π·0 β πΏ πΌ, πΎ|π·0 πΌπ0 1ππ₯π π0πΌ 5.3.21
π πΎπ|πΌ, πΎ π , π·0 β πΏ πΌ, πΎ|π·0 πΎπ0 1ππ₯π π0πΎ 5.3.22
5.3.2.3BayesianmodellingforTTRwithrightβcensoreddata
Suppose the Time to Repair (TTR) data t t , t , β― , t for n individuals are i. i. d., and each ln t corresponds to a normal distribution N ΞΌ, Ο . We can get t βs lognormal distribution with parameters ΞΌ and Ο , denoted by LN ΞΌ, Ο . Then, the p. d. f. and c. d. f. are given, respectively, by equation (5.3.23) and equation (5.3.24):
π π‘ |π, π1
β2πππ‘ππ₯π
12π
ππ π‘ π 5.3.23
πΉ π‘ |π, π Ξ¦ππ π‘ π
π 5.3.24
The likelihood function related to π and π , considering the censoring indicators π£π£ , π£ , β¦ , π£ and the observed data set π·0 π, π‘, π£ , becomes
πΏ π, π|π· 2ππ β ππ₯π1
2πππ π‘ π
π‘ 1 Ξ¦ππ π‘ π
π 5.3.25
Chapter 5 Results and Discussion
78
In this study, we assume ΞΌ to be a normal distribution denoted by N e , f as its prior distribution, written as Ο ΞΌ|e , f , and we assume Ο to be a gamma distribution denoted by G g , h as its prior distribution, written as Ο Ο|g , h . This means
π π|π , π β π ππ₯ππ2
π π 5.3.26
π π|π , β β π ππ₯π β π (5.3.27)
Therefore, the joint posterior distribution can be obtained according to equations (5.3.25) to (5.3.27) as
π π, π|π· β πΏ π, π|π· π π |π , π π π|π , β 5.3.28
The parametersβ full conditional distribution with Gibbs sampling can be written as
Ο π |π , π, π· β πΏ π, π|π· π0
12ππ₯π
π0
2π π0
2 5.3.29
Ο π |π, π , π· β πΏ π, π|π· π ππ₯π β π 5.3.30
5.3.2.4Resultsofthecasestudy
In this case study of five balling drums, the Markov chain is constructed for each MCMC simulation. A burn-in of 1000 samples is used, with an additional 10,000 Gibbs samples for each Markov chain. Vague prior distributions are adopted as follows:
For the Bayesian Weibull model using TTF data:
πΌ~πΊ 0.0001, 0.0001 , πΎ~πΊ 0.0001, 0.0001 ;
For the Bayesian lognormal model using TTR data:
π~π 0, 0.0001 , π~πΊ 0.0001, 0.0001 .
KPI framework for maintenance management through eMaintenance
79
Table 5.3.4 Posterior statistics in Bayesian Weibull model with censored TTF data
Ballingdrum Parameter Mean SD MCerror 95%HPDinterval
1 πΌ 0.5399 0.0235 4.34E-4 (0.4954, 0.5870) πΎ 0.0934 0.0122 2.26E-4 (0.0710, 0.1186)
2 πΌ 0.5721 0.0289 6.25E-4 (0.5159, 0.6295) πΎ 0.0651 0.0110 2.39E-4 (0.0459, 0.0890)
3 πΌ 0.5781 0.0251 5.08E-4 (0.5299, 0.6281) πΎ 0.0742 0.0104 2.09E-4 (0.0555, 0.0961)
4 πΌ 0.5713 0.0252 5.14E-4 (0.5228, 0.6210) πΎ 0.0763 0.0109 2.22E-4 (0.0569, 0.0992)
5 πΌ 0.5601 0.0219 3.95E-4 (0.5176, 0.6038) πΎ 0.0940 0.0111 1.99E-4 (0.0735, 0.1175)
Using convergence diagnostics (i.e. checking dynamic traces in Markov chains, determining time series and Gelman-Rubin-Brooks (GRB) statistics, and comparing MC error with standard deviation (SD)) (Lin, 2014), we consider the posterior distribution statistics shown in Table 5.3.4 and Table 5.3.5, including the parametersβ posterior distribution mean, SD, Monte Carlo error (MC error), and 95% highest posterior distribution density (HPD) interval.
Table 5.3.5 Posterior statistics in Bayesian lognormal model with censored TTR data
Ballingdrum Parameter Mean SD MCerror 95%HPDinterval
1 π -0.4501 0.0882 4.98E-4 (-0.6250, -0.2776) π 0.3585 0.0267 1.50E-4 (0.3078, 0.4125)
2 π -0.3825 0.1082 6.24E-4 (-0.5959, -0.1719) π 0.3277 0.0285 1.56E-4 (0.2742, 0.3853)
3 π -0.4510 0.0839 5.10E-4 (-0.6176, -0.2871) π 0.4041 0.0305 1.80E-4 (0.3463, 0.4660)
4 π -0.6124 0.0907 5.29E-4 (-0.7924, -0.4351) π 0.3516 0.0266 1.49E-4 (0.3010, 0.4057)
5 π -0.6023 0.0812 4.72E-4 (-0.7633, -0.4432) π 0.3524 0.0238 1.39E-4 (0.3072, 0.4007)
Using the results from Table 5.3.4 and Table 5.3.5 for balling drums 1 to 5, we derive the distributions of TTF and TTR as shown in Table 5.3.6.
Table 5.3.6 Statistics of individual balling drums with censored data
Ballingdrum
TTF TTR Availabilityπ πΌ, πΎ πΏπ π, π 1 1 πΏπ π, π π πΌ, πΎββ
1 π 0.5399, 0.0934 πΏπ 0.4501, 0.3585 1 1 πΏπ π, π π πΌ, πΎββ 2 π 0.5721, 0.0651 πΏπ 0.3825, 0.3277 1 1 πΏπ π, π π πΌ, πΎββ 3 π 0.5781, 0.0742 πΏπ 0.4510, 0.4041 1 1 πΏπ π, π π πΌ, πΎββ 4 π 0.5713, 0.0763 πΏπ 0.6124, 0.3516 1 1 πΏπ π, π π πΌ, πΎββ 5 π 0.5601, 0.0940 πΏπ 0.6023, 0.3524 1 1 πΏπ π, π π πΌ, πΎββ
Chapter 5 Results and Discussion
80
Using the results in Table 5.3.6, we create the π. π. π. and π. π. π. charts of TTF and TTR data in Figure 5.3.1 and Figure 5.3.2.
(a) π. π. π. of TTF (b) π. π. π. of TTR
Figure 5.3.1 π. π. π. of TTF and TTR
(a) π. π. π. of TTF (b) π. π. π. of TTR
Figure 5.3.2 π. π. π. of TTF and TTR
As discussed above, system availability can be computed via the TTF and TTR, but we cannot obtain a closed-form distribution of system availability. Therefore, we use an empirical distribution instead of an analytical one. We generate 10,000 samples from the distributions of TTF and TTF and calculate the associated availability. Figure 5.3.3 presents the histogram of availability of the five balling drums. We use the Kaplan-Meier estimate as the empirical π. π. π. Figure 5.3.4 shows the empirical distribution of the availability of the five balling drums.
KPI framework for maintenance management through eMaintenance
81
Figure 5.3.3 Histogram plot of availability
Figure 5.3.4 Empirical π. π. π. of availability
Table 5.3.7 Statistics of individual balling drums with censored data
BallingdrumMTTF MTTR Availability
Mean 95% HPD interval Mean 95% HPD interval Mean 95% HPD interval 1 145.0 (118.4, 178.2) 2.616 (2.000, 3.437) 0.9821 (0.9753, 0.9873) 2 197.0 (157.6, 247.5) 3.223 (2.301, 4.540) 0.9837 (0.9759, 0.9893) 3 146.0 (120.7, 177.0) 2.239 (1.741, 2.864) 0.9848 (0.9795, 0.9890) 4 149.0 (122.5, 181.8) 2.289 (1.736, 3.041) 0.9847 (0.9788, 0.9891) 5 115.0 (96.40, 137.5) 2.296 (1.796, 2.958) 0.9803 (0.9736, 0.9855)
Chapter 5 Results and Discussion
82
We calculate the availability of the individual balling drums in Table 5.3.7, where MTTF = πΈ π π‘ |πΌ, πΎ , and MTTR = πΈ π π‘ |π, π . Then, according to the assumption that it is treated as a parallel system, the system availability of the five balling drums is
π΄π π¦π π‘ππ 1 1 π΄π
5
π 1
0.99
5.3.2.5Acomparisonstudy
For comparative purposes, Table 5.3.8 and Table 5.3.9 show the statistics of the individual balling drums with no censored data. All TTF and TTR data collected in Stage I are treated as reasonable and require no improvement.
Table 5.3.8 Statistics of individual balling drums with no censored data
Ballingdrum
TTF TTR Availabilityπ πΌ, πΎ πΏπ π, π 1 1 πΏπ π, π π πΌ, πΎββ
1 π 0.5409, 0.0928 πΏπ 0.1842, 0.2270 1 1 πΏπ π, π π πΌ, πΎββ
2 π 0.5747, 0.0642 πΏπ 0.0075, 0.1861 1 1 πΏπ π, π π πΌ, πΎββ
3 π 0.5975, 0.0712 πΏπ 0.4574, 0.2196 1 1 πΏπ π, π π πΌ, πΎββ 4 π 0.5745, 0.0750 πΏπ 0.3540, 0.2184 1 1 πΏπ π, π π πΌ, πΎββ 5 π 0.5660, 0.0958 πΏπ 0.3484, 0.2195 1 1 πΏπ π, π π πΌ, πΎββ
Table 5.3.9 Statistics of individual balling drums with no censored data
BallingdrumMTTF MTTR Availability
Mean 95% HPD interval Mean 95% HPD interval Mean 95% HPD interval 1 145.0 (118.1, 178.0) 7.779 (5.284, 11.58) 0.9487 (0.9229, 0.9665) 2 196.4 (157.7, 256.0) 15.48 (8.927, 26.60) 0.9265 (0.8766, 0.9582) 3 128.7 (127.9, 155.0) 6.381 (6.194, 9.622) 0.9525 (0.9538, 0.9693) 4 148.5 (122.5, 180.3) 7.178 (4.755, 10.86) 0.9536 (0.9291, 0.9702) 5 115.8 (115.1, 139.0) 7.083 (6.926, 10.22) 0.9420 (0.9433, 0.9610)
For convenience, the results are also listed in Table 5.3.10.
Table 5.3.10 Comparison of statistics with and without censored data
Ballingdrum
MeanofMTTF MeanofMTTR MeanofAvailabilityNo
censored Censored %
No censored
censored % No
censored censored %
1 145.0 145.0 0 7.779 2.616 66.37 0.9487 0.9821 3.52 2 196.4 197.0 0.30 15.48 3.223 79.18 0.9265 0.9837 6.17 3 128.7 146.0 13.4 6.381 2.239 64.91 0.9525 0.9848 3.39 4 148.5 149.0 0.33 7.178 2.289 68.11 0.9536 0.9847 3.26 5 115.8 115.0 0 7.083 2.296 67.58 0.9420 0.9803 4.07
KPI framework for maintenance management through eMaintenance
83
In Table 5.3.10, β%β denotes the percentage after considering the censored data. For instance, for balling drum 1, after considering the censored data, the mean of MTTF does not change; MTTR improves by 66.37%, and availability improves by 3.52%.
According to the results from Table 5.3.10, if 20% of the abnormal TTR data could be improved (for instance, by applying RCA activities, or more specifically, by improving maintenance resource management, including maintenance skills, spare parts, etc.), the TTR could be improved by 66.37%, 79.18%, 64.91%, 68.11%, and 67.58% for drums 1 to 5, respectively. Meanwhile, the availability would be improved by 3.52%, 6.17%, 3.39%, 3.26%, and 4.07% for drums 1 to 5, respectively.
The improvement of the TTF is not as impressive. We apply right-censored data for the TTRs under the assumption that they can be improved (censored at six), but the corresponding TTFs can only be marked as censored instead of censored at some specified value, under the assumption that the maintenance interval will not change all that much. This implies that if the maintenance interval (for instance, the preventive maintenance) could be improved, the TTFs could be improved (censored at a larger value), thus improving the availability.
5.3.2.6ConnectionbetweentechnicalandsoftKPIs
In the studied company, Key Performance Indicators (KPIs) are divided into two groups: technical KPIs and soft KPIs. The former are related to the performance of equipment, whilst the latter focus on maintenance management.
In this case, the abnormal values of TTR are assumed to be mainly caused by lack of maintenance resources, including personnel with suitable skills, spare parts, etc. KPIs for maintenance resources are treated as soft KPIs in the company. Therefore, using our comparative approach, we can easily find out how the technical KPIs (TTF, availability of assets) would be influenced by improving soft KPIs.
5.3.2.7Applicationofthethresholdasamonitoringline
In this study, the threshold of abnormal TTR values in the work orders is determined by a β80-20β rule in Pareto analysis, in which a TTR value exceeding six is treated as an abnormally long time for TTR and should be improved by RCA activities, including improving maintenance resource management.
Actually, the threshold could be determined by the company according to its business goals; for instance, it could be set at 70% or 90%, or set according to other rules combined with business goals. The threshold could also be changed gradually to improve the maintenance step by step, following a PDCA process. In another words, the so-called abnormal data are not really abnormal. Finally, the threshold could be treated as a monitoring line, permitting the dynamic monitoring of system availability.
Chapter 5 Results and Discussion
84
5.3.2.8Otherdiscussionsrelatedtothiscasestudy
In this study, since the five balling drums are relatively new, the gamma distributions and normal distributions are selected as vague priors due to lack of real prior information. This could be improved with more historical data/experience.
The system configurations could be extended to other more complex architectures (series, k-out-of-n, stand-by, multi-state, or mixed).
The results of system availability are all larger than 0.99, with or without considering censored data. The difference is not very obvious for two reasons. First, the system configuration is assumed in parallel; second, the individual balling drums have relatively high availabilities (higher than 0.9). The difference (with or without considering censored data) will be more obvious with other system configurations and less individual availability.
For TTF data, the shape parameter for the Weibull distribution is less than 1. The TTFs have a decreasing trend (as in the early stage of the bathtub curve) which is not suitable for the real-world experience of mechanical equipment. However, the TTF data include not only corrective maintenance but also preventive maintenance. The decreasing trends suggest a possible way to improve TTF is to improve the preventive maintenance plan.
5.3.3 AssessmentofsoftKPIs
This study proposes approaches to assessing soft KPIs using forecasting methods for continuous, intermittent and slow moving data. For soft KPIs (e.g. work orders) whose distribution cannot be easily determined, we apply approaches such as time series analysis if the data are continuous or fast moving. We apply Croston analysis if the data are intermittent and or Bootstrap analysis if the data are slow moving. For the purpose of illustration, this section adopts data from work orders of the studied company.
5.3.3.1Timeseriesforecasting
Suppose that the time series for some kind of work orders (e.g., spare parts with fast consumption) are as below; Table 5.3.11 and Figure 5.3.5 indicate the plots of the times series data. The procedure is shown in Table 5.3.12.
Table 5.3.11 Time series data from the work orders: an example
Year/Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 2013 3 1 5 4 1 4 0 2 1 2 4 4 2014 3 1 4 0 1 3 2 1 3 4 7 7 2015 3 5 1 1 3 1 7 1 4 7 4 2 2016 5 2 3 3 3 6 11 2 1 10 3 6 2017 6 5 4 2 1 1 4 4 3 7 5 3 2018 5 8 3 7 11 0 7 7 4 6 5 8
KPI framework for maintenance management through eMaintenance
85
(a) Time series plot of work order data
(b) Work order data with no trend
Figure 5.3.5 Time series data from the work orders: an example
Using the the auto.arima function, we determine that the best model to fit the data is the ARIMA (2, 1, 2). The auto-correlation function (ACF) and partial auto-correlation function (PACF) diagrams for the data appear below.
Table 5.3.12 The procedure of time series forecasting
Steps Procedure1 Stationarize the time series data, if necessary, by differencing, 2 Transform the time series data, if necessary to make variance constant.
3 Study the pattern of autocorrelations and partial autocorrelations to determine if lags of the stationarized series and/or lags of the forecasted errors should be included in the forecasting equation.
4 Fit the suggested model and check its residual diagnostics, particularly the residual ACF and PACF plots, to see if all coefficients are significant and the entire pattern has been explained.
5 Patterns that remain in the ACF and PACF may suggest the need for additional AR or MA terms.
Chapter 5 Results and Discussion
86
(a) ACF diagram
(b) PACF diagram
Figure 5.3.6 Time series data from the work orders: an example
Results from the forecasted model are shown in Figure 5.3.7; it is shown with 12 months(year 2019) of detailed estimates in Table 5.3.13.
Figure 5.3.7 Forecasted work orders
Table 5.3.13 Forecast of 12 months of work orders
Year/Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec 2019 5 5 6 5 6 5 6 6 6 6 6 6
KPI framework for maintenance management through eMaintenance
87
(a) ACF diagram of residuals
(b) Histogram of forecast errors
Figure 5.3.8 Histogram of forecast errors
Figure 5.3.8 (a) shows that none of the sample autocorrelations for lags 1-20 exceed the significance bounds; meanwhile, in this case the p-value for the Ljung-Box test is 0.78, therefore, we conclude that the evidence for non-zero autocorrelations in the forecast errors at lags 1-20 is not obvious.
Figure 5.3.8 (b) shows that the forecast errors are roughly normally distributed and the mean seems to be close to zero. Therefore, it is plausible that the forecast errors are normally distributed with mean zero and constant variance.
Additionally, since successive forecast errors do not seem to be correlated, and the forecast errors seem to be normally distributed with mean zero and constant variance, the ARIMA(2,1,2) does seem to provide an adequate predictive model for the number of work orders in this study.
5.3.3.2Crostonforecasting
The Croston method is used to predict intermittent demand. It performs exponential smoothing prediction by dividing the general time series into non-zero demand time interval series and non-zero demand series. An example is shown in Table 5.3.14, Figure 5.3.9 and 5.3.10 for spare parts consumption.
Table 5.3.14 Spare parts demand
Months 1 2 3 4 5 6 7 8 Demand 0 0 2 0 0 5 0 2
The forecasts are made using R. Table 5.3.15 shows the results of the forecasts using the original Croston method, referred to in the table as Croston, and two variants of Croston: Syntetos-Boylan Approximation (SBA) and Shale-Boylan-Johnston (SBJ). As the table shows, Croston forecasts a bit less demand at shorter intervals and very high average
Chapter 5 Results and Discussion
88
demand rates. SBA and SBJ forecast higher demand rates and higher intervals but less average demand rates. In Table 5.3.15, estimated results is calculated according to predicted results; since in reality the amount of spare parts should be an integer. The estimated results show only Croston forecasts a bit less demand at shorter intervals.
Figure 5.3.9 Histogram of spare parts
Figure 5.3.10 Line graph of spare parts demand
Table 5.3.15 Result among variants of the Croston method
Croston SBA SBJ
Predicted Estimated Predicted Estimated Predicted Estimated Demand 2.54 3 2.66 3 2.65 3 Interval 2.16 2 2.86 3 2.83 3
Demand Rate 1.18 1 0.88 1 0.88 1
Figures 5.3.11 to 5.3.13 plot the predicted outputs as graphs. The first red line indicates in-sample fit while the second red line from 9 to 14 indicates the predicted demand for the next six months.
KPI framework for maintenance management through eMaintenance
89
Figure 5.3.11 Croston forecast
Figure 5.3.12 Croston-SBA forecast
Figure 5.3.13 Croston-SBJ forecast
Chapter 5 Results and Discussion
90
5.3.3.3Bootstrapforecasting
The Bootstrap method is a prediction method when the sample size is relatively small and it is difficult to accurately predict based on the assumed distribution. It generates tens of thousands of demand groups accumulated over the lead time period based on the originally small sample and predicts the distribution and average demand of the original time series based on the distribution of the new data generated.
The bootstrap method's prediction results include both the confidence level and the average demand within the period, so it is a better risk prediction method. Simply put, the bootstrap method is a resampling of the sample and the estimated estimator is obtained from the sampled sample. Assuming the time series data are as shown in Table 5.3.16, then Figures 5.3.14 and 5.3.15 show the histogram and line graph of the data.
Table 5.3.16 Bootstrap data sample
Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Demand 0 0 19 0 0 0 4 18 17 0 0 0 Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Month Jan
Demand 0 0 3 0 0 19 0 0 0 5 4 5
Figure 5.3.14 Histogram of spares
KPI framework for maintenance management through eMaintenance
91
Figure 5.3.15 Line graph of spares
The demand for this spare part over the past 24 months is shown in Table 5.3.16, as is the intermittent demand, with non-zero demand (19, 4, 18, 17, 3, 19, 5, 4, 5). Assuming the lead time for the spare part is three months, we now need to predict how much will be consumed in the next three months to prepare our order.
We randomly generate a group of packet data from the lead period size (three months) based on the past 24 data. If we choose 4, 8, 15, the corresponding demand is 0, 18, 3 in advance. The total demand during the period is 21.
According to the above method, we randomly generate 100,000 sets of such data from the computer and calculate the total demand in the lead time.
Based on the large sample data generated randomly, we plot the demand distribution over the lead time as shown in Figure 5.3.16.
Figure 5.3.16 Line graph of spares
Chapter 5 Results and Discussion
92
As can be seen in the figure, the most demanding demand in the lead time is 0, and the probability of its occurrence is about 25%. The demand during the lead time may also be 3, 4, 5, 7, 56 or even more.
The average demand during the lead time is around 14.6. From the distribution of the above data, if the demand in the lead time is predicted with a 95% confidence level, that is, the spare parts inventory is required to have 95% spare parts availability, there should be 41 units of spare parts in the warehouse.
5.4 ResultsanddiscussionrelatedtoRQ4
RQ4: How can the developed KPI framework be improved continuously?
This KPI framework must be improved continuously. To ensure this is possible, we perform a comparison study to reveal the gaps between current and proposed KPIs in the studied mining company, and we adapt a roadmap from the railway industry to develop and review new KPIs.
5.4.1 ComparisonofcurrentandproposedKPIs
Table 5.4.1 is a summary of current KPIs used in the studied company.
When we compare this list with the KPI framework presented in section 5.1, se see that in the studied mining company, at the moment, the existing KPIs are mostly used to measure the performance of the technical system. There is a lack of KPIs to measure the overall maintenance process, especially soft KPIs.
Our proposed KPI framework has 111 soft KPIs, 85 for the maintenance process and 26 for maintenance resources. Following the maintenance process in the IEV standard, this KPI framework provides KPIs to measure maintenance strategy, maintenance planning, maintenance preparation, maintenance execution and maintenance assessment. These form the basis of the maintenance process. Thus, the proposed system is a more holistic performance measurement system; it will be beneficial to this mining organization, as there are some dependencies between soft KPIs and other organizational KPIs as shown in Figure 1.2.
Soft KPIs can affect the technical KPIs in the long run and increase or decrease utilization and plant speed. When utilization and plant speed decrease, total production output will also decrease. In some cases, quality can be affected. Thus, both the soft KPIs and the technical KPIs affect the production KPIs. The values of the soft and technical KPIs reflect how well maintenance activities are going. Ineffective maintenance will not give optimal production and can affect the quality of the product, in this case, iron ore, and/or reduce production times because of breakdowns. Poor production, in turn, will not give good manufacturing execution system (MES) KPIs. This will eventually reduce the marketing KPI values, as customers will not buy products that are not of the highest
KPI framework for maintenance management through eMaintenance
93
quality for high prices, and the companyβs overall KPIs will suffer. Each KPI in the proposed framework has a relationship of some kind with the KPIs above and below it; thus, changes in one KPI have a ripple effect on other KPIs. Recognizing appropriate soft KPIs and improving their values will increase overall capacity utilization, not just in maintenance but in all areas of the organization.
Table 5.4.1 Current KPIs in the studied mining company
Abbreviation (if there is one)
Name of current KPIs
Internal description of current KPIs
T Availability Ready time divided by planned operating (calendar) time. U Utilization Utilized time divided by planned operating (calendar) time.
FU Scheduled
Maintenance Maintenance time.
/
Internal Interference
Disturbance that interferes with its own facility, section, equipment.
External Interference
Disturbance for/after own installation, section, equipment.
Stop Object Time Standing time for equipment. Stop Object
Number Number of stops for equipment.
Stop Cause Time Standby time for breakdown. Stop Cause
Number Number of stops for breakdown.
MTBF Mean Time
Between Failure Operating time added with distortion time divided by the number of disturbances.
MTTF Mean Time To
Failure Operating time divided by number of disturbances.
MDT Mean Down Time Stop time divided by number of disturbances.
TK
1: C
ondi
tion
Mon
itor
ing
Ope
rati
on
TK
2: C
ondi
tion
Mon
itor
ing
Mai
nten
ance
SM: L
ubri
cati
ng R
ound
s
SR: S
top
Rou
nds
Percentage of Completed
Rounds Completed rounds divided with planned rounds.
Share Wrong Completed rounds wrongly shared with completed rounds.
Proportion of Delayed Rounds
Successful rounds reported late divided by completed rounds.
Executed Inspection Points
Completed inspection points.
Unsecured Inspection Points
Unfinished inspection points.
Misspelled Inspection Points
Inspection points with errors.
Completed Work Orders from
Error Message TK1/TK2/SM/SR
Completed work orders from error reporting.
/
Proportion of Planned
Maintenance All maintenance in addition to corrective maintenance.
Share of Planned Work Orders
Percentage of work orders with a scheduled start time, planned completion time, actual start time, actual completion time, real time and calculated time divided by total number of work orders.
Planning Security How estimated time complies with real time. Delivery
Reliability Percentage of work orders completed (actual completion time) before the scheduled completion time.
Chapter 5 Results and Discussion
94
Back Log Open delayed work orders divided by the total number of open AOs.
Mai
nten
ance
Sto
p The Proportion of Planned
maintenance
Percentage of work orders with a scheduled start time, planned completion time, actual start time and actual completion time divided by total number of work orders.
Planning Security How scheduled time matches real time. Delivery
Reliability Percentage of work orders completed (actual completion time) before the scheduled completion time.
Backlog Open delayed work orders divided by the total number of open work orders.
Mai
nten
ance
wor
k or
der
Trend Error Report / AO
proposal
Registration date and number or error reports accumulated over time.
Trend Released Work Orders
Date of release and number of work orders accumulated over time
Status Closed Work Order
Date of actual completion time and number of work orders accumulated over time.
/ SEK / Ton Financial outcome divided by tons of pellets. K Product Quality Approved production divided by total production. / Speed loss Under study.
5.4.2 OptimizationoftheproposedKPIs
A world class organization is dynamic and relies on continuous improvement of its work processes to retain its position as a world leader. An approach from the railway industry, the short name of which is In2Rail, is useful for developing new KPIs, and reviewing or improving existing KPIs so that they do not become old and irrelevant.
As reported by In2Rail, different organizations use different methods to define and measure their indicators. For example, a group may discuss the companyβs required KPIs and decide their relevance. This approach is highly subjective, however; a better and more objective approach is to follow established guidelines to define and evaluate indicators.
A good performance measurement system provides the data to answer the questions an organization needs to answer if it is to manage its performance effectively. For the studied mining company, the proposed KPIs will help to ensure high capacity utilization which will translate into good product quality, reduced costs, improved employee skills, and maintenance innovation. In addition to ensuring the companyβs vision is upheld, the KPIs will meet the following goals:
Be one of the three best in the world for maintenance in the mining industry. Work in a safe and environmentally friendly manner. Take a uniform and systematic approach to maintenance. Have committed and competent staffs who considers working in maintenance to
be attractive. Ensure staffs have knowledge of the construction and function of the plants,
making it possible to increase the proportion of operator maintenance. Design operational safety from a cost-effective perspective.
KPI framework for maintenance management through eMaintenance
95
Work on continuous improvements as a natural way of working. Design maintenance measures based on facts, analysis and long-term needs. Design maintenance based on plant values unless otherwise decided.
Although Neelyβs KPI definition guide is detailed which is introduced in Chapter 2, it has drawbacks. For one thing, the method is very time-consuming. For this reason, we have modified the ten steps of the KPI definition and use what is of interest to us; we provide a context and a purpose, a time frame definition and a general formula for each KPI suggested in the framework. We have left out who measures and who acts on the data (owner) as this will be taken care of by the studied company when they use the KPIs. We have also compressed the other eight steps and made them into four broad steps. See βNumber of Shutdownsβ for clarification.
****************************************************************************************
NumberofShutdownsContextandPurpose:Numberofshutdownsisthetotalnumberoftimestheassetisoutofservice.ThisKPIhelpstounderstandthenumberoftimestheequipment,productionlineorprocessunitisoutofserviceduringthequeryperiod. Italso includesthestoppingofequipmentortheshuttingdownofaproductionlineorprocessunittoconductplannedmaintenance.Thelowerthenumberof shutdown times, in particular, the asset failure times, the better the assetmanagement. Anavailableassetensureshigherproduction.TimeDefinition:Stopdate/workorderregistrationdateοΏ½(querystartdate,queryterminationdate)GeneralFormula:Count(numberofregisteredstops)
****************************************************************************************
After the KPI has been defined, we need to verify it. This can be done with the following verification questions provided by Neely:
1. The Truth Test: Are we really measuring what we set out to measure? 2. The Focus Test: Are we only measuring what we set out to measure? 3. The Relevancy Test: Is it the right measure of the performance factor we want to
track? 4. The Consistency Test: Will the data always be collected in the same way whoever
measures them? 5. The Access Test: Is it easy to locate and capture the data needed to make the
measurement? 6. The Clarity Test? 7. The So-What Test: Can and will the reported data be acted upon? 8. The Timeliness Test: Can the data be accessed rapidly and frequently enough for
action? 9. The Cost Test: Is the measure worth the cost of measurement? 10. The Gaming Test: Is the measure likely to encourage undesirable or
inappropriate behaviours? Since the development of KPIs is an ongoing process, the verification will also be ongoing.
Chapter 5 Results and Discussion
96
KPI framework for maintenance management through eMaintenance
97
Chapter6
Conclusions,contributionsandfutureresearch
This chapter concludes the research, summarizes the contributions and suggests future research.
6.1Conclusions
This study develops an integrated KPI framework for maintenance management in an eMaintenance environment. It explores the implementation of each proposed KPI in the mining environment. The study proposes a novel approach to assess technical and soft KPIs and discovers connections between technical and soft KPIs. By comparing the current situation in the mining company to the experience of other industries, it suggests ways to optimize the proposed KPIs through continuous improvement.
The three research questions (RQs) given in Chapter 1 have been answered as follows:
RQ1: What is a KPI framework for maintenance management?
This study develops a KPI framework consisting of technical KPIs (linked to machines) and soft KPIs (linked to maintenance workflow) to control and monitor the entire maintenance process to achieve the overall goals of the organization.
The proposed KPI framework has 134 KPIs divided into technical and soft KPIs as follows: asset operation management has 23 technical KPIs, maintenance process management has 85 soft KPIs and maintenance resources management has 26 soft KPIs.
The proposed KPI framework makes use of four hierarchical levels. o The first level, the asset management system, is the highest level in the
framework and encapsulates the second, third and fourth levels. o The second level consists of three broad categories; asset operation
management, maintenance process management and maintenance resources management. Asset operation management is used to track the technical aspects of the maintenance process while maintenance process management and maintenance resources management are used to track the soft aspects of the maintenance process.
o The third level is a further breakdown of the second-level categories. That is, asset operation management is broken down into five categories: overall asset, availability, reliability, maintainability and safety.
Chapter 6 Conclusions, contributions and future research
98
Maintenance process management is broken down into five categories: maintenance management, maintenance planning, maintenance preparation, maintenance execution and maintenance assessment. Finally, maintenance resources management is broken down into three categories: spare parts management, outsourcing management and human resources management.
o In level four, the KPIs are grouped into common measures. Results from this study will be applied to the studied company and supply the
guidance of developing the KPI framework.
RQ2: How can the developed KPI framework be implemented through eMaintenance?
Implementation of the proposed KPI framework has been discussed and timelines, definitions and general formulas given for each specified KPI. These will further support to develop KPI ontology and taxonomy of the proposed KPI.
Results from this study will be applied to the studied mining company and guide the implementation of the proposed KPIs in an eMaintenance environment.
RQ3: How can the KPIs be assessed using novel approaches?
This study proposes parametric Bayesian approaches to assess system availability in the operational stage. With these approaches, MTTF and MTTR can be treated as distributions instead of being βaveragedβ by point estimation. This better reflects reality.
MCMC is adopted to take advantage of both analytical and simulation methods. Because of MCMCβs high dimensional numerical integral calculation, the selection of prior information and descriptions of reliability/maintainability can be more flexible and realistic. The limitations of simulation data sample size are also overcome.
In the case studies, TTF and TTR are determined using a Bayesian Weibull model and a Bayesian lognormal model, respectively.
The proposed approach can integrate analytical and simulation methods for system availability assessment and could be applied to other technical problems in asset management (e.g., other industries, other systems).
By comparing the results with and without considering the threshold for censoring data, we show there is a connection between technical and soft KPIs, and the threshold can be used as a monitoring line for continuous improvement in the investigated mining company.
For those soft KPIs for which the distribution of data collected from eMaintenance system (e.g., work orders) is not easily determined, we could apply approaches, such as Time series analysis (if the data are βfast movingβ), Croston analysis (if the data are βintermittentβ), or Bootstrap analysis (if the data are βslow movingβ). The proposed approaches from this study could also be applied to other technical problems in asset management (e.g., other industries, other system).
KPI framework for maintenance management through eMaintenance
99
RQ4: How can the developed KPI framework be improved continuously?
A comparison study shows that, at the moment, the studied company uses about 26 KPIs. Out of the 26 KPIs, 1 KPI called βspeed lossβ is under study and only works in one processing plant. The existing KPIs are mostly used to measure the performance of the technical system. The company lacks KPIs to measure the overall maintenance process, especially soft KPIs.
This study introduces an approach for developing new KPIs, reviewing or improving existing KPIs so that they do not become old and irrelevant. This is necessary because organizations are not static entities. A world class organization is dynamic and relies on continuous improvement of its work processes to retain its position as a world leader.
6.2Contributions
The main contributions of this research can be summarized as follows:
An integrated KPI framework for maintenance management in a mining company is developed. This framework consists of technical KPIs (linked to machines) and soft KPIs (linked to maintenance workflow) to control and monitor the entire maintenance process to achieve the overall goals of the organization.
Implementation of the developed KPI framework is discussed, and timelines, definitions and general formulas are given for each specified KPI. Results from this study could be applied to the studied company to develop KPI ontology and taxonomy and guide the implementation of the proposed KPIs through eMaintenance.
Novel approaches to assessing both technical and soft KPIs are proposed. In particular, Bayesian approaches using MCMC can take advantage of the analytical and simulation methods for assessing system availability; by setting up a threshold for censoring data, we show there is a connection between technical and soft KPIs, and the threshold can be used as a monitoring line for continuous improvement in the investigated mining company.
Optimization of the developed KPI framework is discussed and an approach to continuous improvement is suggested.
6.3Futureresearch
The following are considered interesting topics for future research.
Since the research was motivated/ financed by a particular mining company, the developed technical (linked to machines) and soft (linked to workflow) KPIs are based on the companyβs business strategies. In the future, a more general framework can be studied for other companies and industries.
The link-and-effect model is not deal with in this study, which should be focused on in the future.
Chapter 6 Conclusions, contributions and future research
100
In this study, costs are not considered sufficiently, as only maintenance is included. In the future, costs could be highlighted in the KPI frameworks in forms of development, implementation, assessment, and optimization.
In this study, the emphasis is on developing a new KPI assessment, so the research uses only a few KPIs as examples because of time and project limitations. In the future, more assessment approaches could be explored.
The integrated KPIs are proposed in general. KPIs for different/specified plants, processes, maintenance tasks (e.g., condition morning, lubrication, etc.) are not studied separately. Further work could be done to minimize this limitation.
KPI framework for maintenance management through eMaintenance
101
REFERENCES
Al-Najjar, B. (2007). The lack of maintenance and not maintenance which costs: A model to describe and quantify the impact of vibration-based maintenance on company's business.InternationalJournalofProductionEconomics,107(1), 260-273.
Alegre, H., Baptista, J. M., Cabrera Jr, E., Cubillo, F., Duarte, P., Hirner, W., Parena, R. (2017). Performanceindicatorsforwatersupplyservices.ThirdEdition. London, UK: IWA publishing.
Aljumaili, M. (2016). Data Quality Assessment: Applied in Maintenance (PhD Thesis). LuleΓ₯ University of Technology, LuleΓ₯, Sweden.
Bourne, M., Melnyk, S., & Bititci, U. S. (2018). Performance measurement and management: Theory and practice. International Journal of Operations & Production Management, 38(11), 2010-2021.
Bourne, M., Mills, J., Wilcox, M., Neely, A., & Platts, K. (2000). Designing, implementing and updating performance measurement systems.International JournalofOperations&ProductionManagement,20(7), 754-771.
Box, G. E., & Jenkins, G. M. (1968). Some recent advances in forecasting and control.JournaloftheRoyalStatisticalSociety.SeriesC(AppliedStatistics),17(2), 91-109.
Box, G., & Tiao, G. (1992). Bayesianinferenceinstatisticalanalysis. New York: John Wiley & Sons.
Brender, D. M. (1968). The Bayesian assessment of system availability: Advanced applications and techniques. IEEEtransactionsonReliability,17(3), 138-147.
Brender, D. M. (1968). The Prediction and measurement of system availability: A Bayesian treatment. IEEETransactionsonReliability,17(3), 127-138.
Campbell, J. D., & Reyes-Picknell, J. (2006). Strategiesforexcellenceinmaintenancemanagement.Productivity Press.
CEN. (2007). SSβEN15341:2007maintenance:Maintenancekeyperformanceindicators. (Swedish Standards Institute ed.) European Committee for Standardization (CEN).
Coetzee, J. (1997). Towards a general maintenance model.ProceedingsofIFRIMβ97,1-9.
Cox, D., & Oakes, D. (1984). Analysisofsurvivaldata. New York: Chapman and Hall.
Dekker, R. & Groenendijk, W. (1995). Availability assessment methods and their application in practice. MicroelectronicsReliability,35(9-10), 1257-1274.
Del-RΓo-Ortega, A., Resinas, M., & Ruiz-CortΓ©s, A. (2010). Defining process performance indicators: An ontological approach. OTMConfederatedInternationalConferences:OntheMoveto
REFERENCES
102
MeaningfulInternetSystems (ss. 555-572). Berlin, Heidelberg: Springer.
Del-RΓO-Ortega, A., Resinas, M., Cabanillas, C., & & Ruiz-CortΓ©s, A. (2013). On the definition and design-time analysis of process performance indicators. InformationSystems,38(4), 470-490.
Diamantini, C., Genga, L., Potena, D., & Storti, E. (2014). Collaborative building of an ontology of key performance indicators. Conference proceeding. OTM Confederated InternationalConferences. October 27-31, 2014. Amantea, Italy.
Dwight, R. (1995). Concepts for measuring maintenance performance.NewDevelopments inMaintenance,109-125.
Dwight, R. (1999a). Frameworksformeasuringtheperformanceofthemaintenancesysteminacapitalintensiveorganisation.(PhD Thesis). DepartmentofMechanicalEngineering,UniversityofWollongong,Wollongong.
Dwight, R. (1999b). Searching for real maintenance performance measures.JournalofQualityinMaintenanceEngineering,5(3), 258-275.
Faghih-Roohi, S., Xie, M., Ng, K. M. & Yam, R. C. (2014). Dynamic Availability Assessment and Optimal Component Design of Multi-state Weighted k-out-of-n Systems. ReliabilityEngineeringandSystemSafety, 123, 57-62.
Galar, D. & Kumar, U. (2016). Maintenance audits handbook: A performance measurementframework (First Edition). Florida, USA: CRC Press.
Gelman, A., Carlin, J., Stern, H., & Rubin, D. (2004). Bayesiandataanalysis. New York: Chapman and Hall/CRC.
Hougaard, P. (2000). Analysisofmultivariatesurvivaldata. New York: Springer-Verlag.
IEC. (2004). 60300-3-14, βDependability managementβPart 3-14: Application guideβMaintenance and maintenance supportβ.BritishStandard.
Jantunen, E., Emmanouilidis, C., Arnaiz, A., & Gilabert, E. (2011). E-maintenance: Trends, challenges and opportunities for modern industry.IFACProceedings,44(1), 453-458.
Kajko-Mattsson, M., Karim, R., & Mirijamdotter, A. (2011). Essential components of eMaintenance. International JournalofPedagogy, InnovationandNewTechnologies,7(6), 555-571.
Kans, M., & Galar, D. (2017). The Impact of Maintenance 4.0 and Big Data Analytics within Strategic Asset Management. Conference proceedings. 6th International Conference onMaintenancePerformanceMeasurement andManagement (MPMM 2016), 28 November 2016, LuleΓ₯, Sweden.
Kaplan, R. S., & Norton, D. P. (1992). The balanced scorecard-measures that drive performance. Harvard Business Review, 70(1), 71-79.
Karim, R. (2008). AserviceβorientedapproachtoeβMaintenanceofcomplextechnicalsystems(PhDThesis).LuleΓ₯UniversityofTechnology,LuleΓ₯,Sweden.
KPI framework for maintenance management through eMaintenance
103
Karim, R., Westerberg, J., Galar, D. & Kumar, U., (2016) . Maintenance analyticsβthe new know in maintenance. IFAC-PapersOnLine, 49(28), 214-219.
Khan, M. A. & Islam, H. (2012). Bayesian analysis of system availability with half-normal life time. QualityTechnologyandQuantitativeManagement,9(2), 203-209.
Koc, M., & Lee, J. (2001). A system framework for next-generation eMaintenance systems.ChinaMechanicalEngineering,5, 14.
Koc, M. & Lee, J., 2003. E-manufacturing-fundamentals, requirements and expected impacts. InternationalJournalofAdvancedManufacturingSystems, 6(1), 29β46.
Kour, R., Aljumaili, M., Karim, R., & Tretten, P. (2019). eMaintenance in railways: Issues and challenges in cybersecurity.ProceedingsoftheInstitutionofMechanicalEngineers,PartF:JournalofRailandRapidTransit.doi:doi.org/10.1177/0954409718822915
Kourentzes, N. (2014). On intermittent demand model optimisation and selection.InternationalJournalofProductionEconomics,156, 180-190.
Kumar, U., & Ellingson, H. (2000). Development and implementation of maintenance performance indicators for the norweigan oil and gas industry. Conference Proceeding. The14thInternationalMaintenanceCongress(Euroβmaintenance,2000),7β10 March 2000, Gothenburg, Sweden.
Kumar, U., Galar, D., Parida, A., StenstrΓΆm, C., & Berges, L. (2013). Maintenance performance metrics: A State-of-the-art review.JournalofQualityinMaintenanceEngineering,19(3), 233-277.
Kuo, W. (1985). Bayesian availability using gamma distributed priors. IIETransactions,17(2), 132-140.
Lawless, J. (1982). Statisticalmodelsandmethodsforlifetimedata. New York: John Wiley & Sons.
Lin, J. (2014). An integrated procedure for Bayesian reliability inference using Markov Chain Monte Carlo Methods. JournalofQualityandReliabilityEngineering,Volume 2014, 1-16.
Lin J. (2016). Bayesian Reliability with MCMC: Opportunities and Challenges. Conference paper published in Book Chapter of Current Trends in Reliability, Availability, Maintainability and Safety. International Conference on Reliability, Safety and Hazard β Advances in Reliability,MaintenanceandSafety(ICRESHβARMS2015). June 14-16, LuleΓ₯, Sweden.
Lingle, J. H., & Schiemann, W. A. (1996). From balanced scorecard to strategic gauges: Is measurement worth it?ManagementReview,85(3), 56.
LΓΆfsten, H. (2000). Measuring maintenance performanceβin search for a maintenance productivity index.InternationalJournalofProductionEconomics,63(1), 47-58.
Marquez, A. C. & Iung, B. (2007). A Structured approach for the assessment of system availability and reliablity using Monte Carlo Simulatoin. Journal of Quality inMaintenance Engineering,13(2), 125-136.
Marquez, A. C., Heguedas, A. S. & Iung, B. (2005). Monte Carlo-based assessment of system
REFERENCES
104
availability. A Case study for cogeneration plants. ReliabilityEngineeringandSystemSafety,88, 273-289.
Muchiri, P., Pintelon, L., Gelders, L., & Martin, H. (2011). Development of maintenance function performance measurement framework and indicators. International Journal of ProductionEconomics,131(1), 295-302.
Muller, A., Crespo Marquez, A., & Iung, B. (2008). On the concept of eMaintenance: Review and current research. ReliabilityEngineering&SystemSafety, 93(8), 1165-1187.
Neely, A. (1999). The performance measurement revolution: Why now and what next?InternationalJournalofOperations&ProductionManagement,19(2), 205-228.
Negri, E., Fumagalli, L., & Garetti, M. (2015). Approach for the use of ontologies for KPI calculation in the manufacturing domain. XX Summer School "Francesco Turco" β IndustrialSystemsEngineering, (ss. 16-18). Napoli, Italy.
Ocnasu, A. B., BΓ©sanger, Y., Rognon, J. P., & Carer, P. (2007). Distribution system availability assessment monte carlo and antithetic variates method. Conference Proceeding. 19thInternationalConferenceonElectricityDistribution, 21st May -24th May, 2007. Vienna, Austria.
Parida, A. (2006). Development of a multiβcriteria hierarchical framework for maintenanceperformance measurement: Concepts, issues and challenges (PhD Thesis). LuleΓ₯ University ofTechnology,LuleΓ₯,Sweden.
Parida, A., & Chattopadhyay, G. (2007). Development of a multi-criteria hierarchical framework for maintenance performance measurement (MPM). Journal of Quality in MaintenanceEngineering,13(3), 241-258.
Parida, A., & Kumar, U. (2004). Managing information is key to maintenance effectiveness. Conference Proceeding. IMS2004 InternationalConferenceon IntelligentMaintenanceSystems, 15th July -17th July. Arles, France.
Parida, A. & Kumar, U., (2006). Maintenance performance measurement (MPM): issues and challenges. JournalofQualityinMaintenanceEngineering,12(3), 239-251.
Parmenter, D. (2007). Keyperformanceindicators:Developing,implementing,andusingwinningKPIs John Wiley & Sons.
Pascual, D. G., & Kumar, U. (2016). Maintenanceauditshandbook:Aperformancemeasurementframework. CRC Press.
Popova, V., & Alexei, S. (2010). Modeling organizational performance indicators. Informationsystems,35(4), 505-527.
Press, S. (1991). Bayesianstatistics:Principles,models,andapplications. New York: John Wiley & Sons Inc.
Pritchard, R. D., Roth, P. L., Jones, S. D., & Roth, P. G. (1990). Implementing feedback systems to enhance productivity: A practical guide. NationalProductivityReview,10(1), 57β67.
Rachman, A. (2019). ArtificialIntelligenceApproachestoLeanRiskβBasedInspectionAssessment
KPI framework for maintenance management through eMaintenance
105
(PhDThesis). University of Stavanger, Stavanger, Norway
Raje, D., Olaniya, R., Wakhare, P. & Deshpande, A. (2000). Availability assessment of a two-unit stand-by pumping system. ReliabilityEngineeringandSystemSafety,68, 269-274.
Schmidt, B. (2018). Toward PredictiveMaintenance in a CloudManufacturingEnvironment: apopulationβwideapproach(PhDthesis). University of SkΓΆvde, SkΓΆvde, Sweden.
Shale, E. A., Boylan, J. E., & Johnston, F. (2006). Forecasting for intermittent demand: The estimation of an unbiased average.JournaloftheOperationalResearchSociety,57(5), 588-592.
Sharma, K. & Bhutani, R. (1993). Bayesian analysis of system availability. MicroelectronicReliability,33(6), 809-811.
Shenstone, L., & Hyndman, R. J. (2005). Stochastic models underlying croston's method for intermittent demand forecasting.JournalofForecasting,24(6), 389-402.
StenstrΓΆm, C. (2014). Operationandmaintenanceperformanceofrailinfrastructure:ModelandMethods.Doctoralthesis,LuleΓ₯UniversityofTechnology,Sweden.
Syntetos, A. A., & Boylan, J. E. (2001). On the bias of intermittent demand estimates.InternationalJournalofProductionEconomics,71(1-3), 457-466.
SΓΆderholm, P. (2005). Maintenance and continuous improvement of complex systems: linkingstakeholder requirements to theuseofbuiltβin test systems.Doctoral thesis,LuleΓ₯UniversityofTechnology,Sweden.
Teunter, R. H., Syntetos, A. A., & Babai, M. Z. (2011). Intermittent demand: Linking forecasting to inventory obsolescence.EuropeanJournalofOperationalResearch,214(3), 606-615.
Therneau, T., & Grambsch, P. (2000). Appliedsurvivalanalysis. New York: Springer.
Tsang, A. H. (2000). Maintenance performancemanagement in capital intensive organizations(PhD Thesis). UniversityofToronto,Toronto,Canada.
Tsang, A. H. (2002). Strategic dimensions of maintenance management. JournalofQuality inMaintenanceEngineering,8(1), 7-39.
Ucar, M., & Qiu, R. G. (2005). eMaintenance in support of e-automated manufacturing systems.JournaloftheChineseInstituteofIndustrialEngineers,22(1), 1-10.
Weber, A., & Thomas, R. (2005). Key performance indicators: Measuring and managing the maintenance function.IvaraCorporation.
Wireman, T. (2005). Developing performance indicators for managing maintenance. SecondEdition. New York: Industrial Press Inc.
Yasseri, S. F. & Bahai, H. (2018). Availability assessment of subsea distribution systems at the architectural level. OceanEngineering, 153, 399-411.
Yin, Robert K. (2014). Casestudyresearch:designandmethods.Thirdedition. Sage Publications, Thousands Oaks, California, USA.
REFERENCES
106
Zio, E., Marella, M. & podofillini, L. (2007). A Monte Carlo simulation approach to the availability assessment of multi-state system with operational dependencies. ReliabilityEngineeringandSystemSafety,92, 871-882.
KPI framework for maintenance management through eMaintenance
107
APPENDIX
Figure A.1 Overall asset KPIs
Figure A.2 Availability KPIs
Figure A.3 Reliability KPIs
APPENDIX
108
Figure A.4 Maintainability KPIs
Figure A.5 Safety KPIs
KPI framework for maintenance management through eMaintenance
109
Figure A.6 Maintenance Strategy KPIs
APP
END
IX
110
Num
ber
of P
lann
ed
Wor
k O
rder
s Cr
eate
dA
vera
ge P
lann
ed
Exec
utio
n T
ime
Mai
nten
ance
Pla
nnin
gA
sset
Man
agem
ent
Tim
e R
elat
edQ
uant
iity
Rel
ated
Mai
nten
ance
Pro
cess
M
anag
emen
tR
esou
rce
Rel
ated
Cost
Rel
ated
Tot
al N
umbe
r of
Pl
anne
d In
tern
al
Labo
ur H
ours
Tot
al C
ost o
f Pla
nned
H
uman
Res
ourc
es
Ave
rage
Pla
nned
In
tern
al L
abou
r H
ours
Tot
al N
umbe
r of
Pl
anne
d Ex
tern
al
Labo
ur H
ours
Ave
rage
Pla
nned
Ex
tern
al L
abou
r H
ours
Plan
ned
Num
ber
of
Mat
eria
ls U
sed
Ave
rage
Pla
nned
N
umbe
r of
Mat
eria
ls
Use
d
Ave
rage
Pla
nned
Ex
tern
al H
uman
R
esou
rce
Cost
s
Tot
al C
ost o
f Pla
nned
M
ater
ials
Plan
ned
Ave
rage
M
ater
ial C
ost
Labo
ur C
ost R
atio
Plan
ned
Mat
eria
l Cos
t R
atio
Figu
re A
.7 M
aint
enan
ce P
lann
ing
KPI
s
KPI
fram
ewor
k fo
r m
aint
enan
ce m
anag
emen
t thr
ough
eM
aint
enan
ce
111
Plan
ned
Star
t / E
nd
Tim
e R
egis
trat
ion
Rat
eA
ctua
l Spa
re P
arts
Use
R
egis
trat
ion
Rat
e
Mai
nten
ance
Pr
epar
atio
nA
sset
Man
agem
ent
Wor
k O
rder
Fee
dbac
kW
ork
Ord
er C
reat
ion
Mai
nten
ance
Pro
cess
M
anag
emen
tW
ork
Ord
er A
ppro
val
Tot
al N
umbe
r of
Wor
k O
rder
s
Tot
al N
umbe
r of
A
ppro
ved
Wor
k O
rder
s
Tot
al N
umbe
r of
U
napp
rove
d W
ork
Ord
ers
Wor
k O
rder
App
rova
l R
atio
One
-tim
e A
ppro
ved
Wor
k O
rder
Rat
io
Ave
rage
tim
e la
g fo
r R
epor
ting
and
A
ppro
ving
Wor
k O
rder
s
Plan
ned
Spar
e Pa
rts
Reg
istr
atio
n R
ate
Plan
ned
Man
-Hou
r R
egis
trat
ion
Rat
e
Plan
ned
Dow
ntim
e R
egis
trat
ion
Rat
e
Stan
dard
Ope
rati
ng
Plan
Reg
istr
atio
n R
ate
Plan
ned
Wor
k T
ype
Reg
istr
atio
n R
ate
Job
Prio
rity
R
egis
trat
ion
Rat
e
Act
ual M
an-H
our
Reg
istr
atio
n R
ate
Act
ual D
ownt
ime
Reg
istr
atio
n R
ate
Wor
k O
rder
R
egis
trat
ion
Bac
k-Lo
g
Figu
re A
.8 M
aint
enan
ce P
repa
rati
on K
PIs
APP
END
IX
112
Figu
re A
.9 M
aint
enan
ce E
xecu
tion
KPI
s
KPI framework for maintenance management through eMaintenance
113
Figure A.10 Maintenance Assessment KPIs
APPENDIX
114
Figure A.11 Spare Parts Management KPIs
Figure A.12 Outsourcing Management KPIs
KPI
fram
ewor
k fo
r m
aint
enan
ce m
anag
emen
t thr
ough
eM
aint
enan
ce
115
Figu
re A
.13
Hum
an R
esou
rces
Man
agem
ent K
PIs
APP
END
IX
116
KPI framework for maintenance management through eMaintenance
PartII
AppendedPapers
Paper A
Development and implementation of a KPI framework for maintenance management in a mining company
Saari, E., Sun, H-L., Lin, J. and Karim, R. 2019. Development and implementation of a KPI framework for maintenance management in a mining company. International Journal of System
Assurance Engineering and Management. Under Review.
1
Development and implementation of a KPI framework for maintenance management in a mining company
Esi Saari1, Huiling Sun2, Jing Lin1*, Ramin Karim1
1. Division of Operation and Maintenance Engineering, LuleΓ₯ University of Technology, LuleΓ₯, Sweden 2. SKF(China) Co.Ltd., Beijing, China
*Corresponding author; E-mail address: [email protected]
Abstract: Performance measurement is critical if organizations want to thrive. The motivation for the research originated from the project βKey Performance Indicators (KPI) for control and management of maintenance process through eMaintenanceβ, initiated and financed by a mining company in Sweden. The main purpose is to develop an integrated KPI framework for the studied mining companyβs maintenance and its implementation through eMaintenance. The proposed KPI framework has 134 KPIs divided into technical and soft KPIs as follows: asset operation management has 23 technical KPIs, maintenance process management has 85 soft KPIs and maintenance resources management has 26 soft KPIs. Its implementation is discussed, and timelines, definitions and general formulas are given for each specified KPI. Results from this study will be applied to the studied company and supply the guidance of implementing those KPIs through eMaintenance.
Keywords: asset management, performance management, Key Performance Indicator (KPI), mining industry.
1. Introduction Performance measurement (PM) is critical to the success of organizations (Bourne, Melnyk, & Bititci, 2018). Those using a balanced or integrated performance measurement system perform better than those that do not (Lingle & Schiemann, 1996) because performance measures provide an important link between strategies and action and thus support the implementation and execution of improvement initiatives (Muchiri, Pintelon, Gelders, & Martin, 2011).
PM requires the formulation of Key Performance Indicators (KPIs), a set of measures that focus on those aspects of organizational performance that are most critical for current and future success (Parmenter, 2007). KPIs demonstrate how effectively a company is achieving key business objectives. They evaluate the companyβs success in reaching targets and the degree to which areas within the company (e.g., maintenance) achieve their goals.
The influence of maintenance on profitability is too high to ignore (Kumar & Ellingson, 2000). With reduced natural resource reserves, e.g. iron ore, oil and gas, and the unstable prices of these resources on the global market, the process industries working with these resources, such as mining companies, must optimise the maintenance process (Kumar & Ellingson, 2000). Because maintenance performs a service function for production, its merits or shortcomings are not always immediately apparent (Muchiri et al., 2011), but it must be measured for companies to remain profitable. This requires the development and use of a suitable set of KPIs.
2
In this paper, we propose a KPI framework to measure the maintenance performance of a Swedish mining company. We define the KPI framework as a system that combines all facets of maintenance actions into a set of measures focusing on aspects of maintenance performance that are most critical for the current and future success of the organization, thus providing a means to quantify the efficiency and effectiveness of its maintenance actions. The importance of an integrated KPI framework for controlling and monitoring the maintenance process cannot be underestimated. It will enable the organization to create internal benchmarks, produce high-quality products at moderate prices, and retain the organizationβs place as a market leader.
Many authors have written about PM, including Kaplan and Norton (1992), Neely (1999), Bourne, Mills, Wilcox, Neely, and Platts (2000), Campbell and Reyes-Picknell (2006), Coetzee (1997), Weber and Thomas (2005), Dwight (1995; 1999b), and Tsang (2000). Some authors have looked specifically at maintenance performance measurement (MPM), including Kumar, Galar, Parida, StenstrΓΆm, and Berges (2013), Parida and Chattopadhyay (2007). These authors proposed measuring the performance of maintenance by focusing on the maintenance process or on the maintenance results (Kumar et al., 2013).
Dwight (1999a) suggested a βvalue-based performance measurementβ, a system audit approach to measuring the maintenance systemβs contribution to organizational success. His approach takes into account the impact of maintenance activities on the future value of the organization, with an emphasis on variations in the lag between actions and outcomes.
Tsang (1998) proposed a strategic approach to managing maintenance performance using a balanced scorecard (Kaplan and Norton, 1992; Kaplan and Norton, 1996). However, the success of the balanced scorecard approach depends on how individual companies use it.
LΓΆfsten (2000) advocated for the use of aggregated measures like the maintenance productivity index, which measures the ratio of maintenance output to maintenance input. But Muchiri et al. (2011) say LΓΆfstenβs approach gives a very limited view of maintenance performance, and it is difficult to quantify different types of maintenance inputs.
More recently, Parida and Chattopadhyay (2007) proposed a multi-criteria hierarchical framework for MPM; the framework includes multi-criteria indicators for each level of management, i.e. the strategic, tactical and operational levels. These multi-criteria indicators are categorized as equipment-/process-related (e.g. capacity utilization, OEE, availability, etc.), cost-related (e.g. maintenance cost per unit of production cost), maintenance-task-related (e.g. the ratio between planned and total maintenance tasks), customer and employee satisfaction, and health, safety and the environment, with indicators proposed for each level of management in each category.
Al-Najjar (2007) designed a model to describe and quantify the impact of maintenance on a businessβs key competitive objectives related to production, quality and cost. The model can be used to assess the cost effectiveness of maintenance investment and provide strategic decision support for different improvement plans.
Muchiri et al. (2011) proposed an MPM system based on the maintenance process and maintenance results. These authors sought to align maintenance objectives with manufacturing and corporate objectives and provide a link between maintenance objectives, maintenance
3
process/efforts and maintenance results. Based on this conceptual framework, they identified performance indicators of the maintenance process and maintenance results for each category. Their conceptual framework provides a generic approach to developing maintenance performance measures with room for customization for individual company needs.
The above proposals are based on both new and existing techniques; some are quantitative and others are qualitative. At this point, there is no integrated approach to measuring the performance of all components of maintenance.
The case study mining company lacks an integrated KPI framework to monitor its maintenance activities. It tried a balanced scorecard, but this was not compatible with the organizational culture. The company has many technical KPIs, i.e. KPIs linked to machines, but very few soft KPIs, i.e. KPIs linked to the maintenance workflow. Whilst it measures the former, it does not measure the latter. Therefore, this study develops a KPI framework consisting of technical KPIs (linked to machines) and soft KPIs (linked to maintenance workflow) to control and monitor the entire maintenance process to achieve the overall goals of the organization. Besides the KPI framework, another contribution and novelty in this study is addressing its implementation by introducing time definition and general formula of each specified KPI.
The paper is set up as follows. The introductory section defines the problem. Section 2 describes the proposed framework. Sections 3 to 5 present the developed KPIs: Section 3 has KPIs for asset operation management, Section 4 has maintenance process management, and Section 5 has maintenance resources management. Section 6 implements the KPIs in the case study mine. Sections 7 and 8 present the discussion and conclusion respectively.
2. KPI Framework A framework is a basic structure underlying a system or concept. It has also been defined as a meta-level model or a higher-level abstraction through which a range of concepts, models, techniques, and methodologies can either be clarified and/or integrated (Jayaratna, 1994).
The proposed KPI framework makes use of a four hierarchical levels. The first level, the asset management system, is the highest level in the framework and encapsulates the second, third, and fourth levels. The second level consists of three broad categories; asset operation management, maintenance process management and maintenance resources management. Asset operation management is used to track the technical aspects of the maintenance process while maintenance process management and maintenance resources management are used to track the soft aspects of the maintenance process. The third level is a further breakdown of the second-level categories. That is, asset operation management is broken down into five categories: overall asset, availability, reliability, maintainability and safety. Maintenance process management is broken down into five categories: maintenance management, maintenance planning, maintenance preparation, maintenance execution and maintenance assessment while maintenance resources management is broken down into three categories: spare parts management, outsourcing management and human resources management (See Figure 1). In level four, the KPIs are grouped into common measures.
4
In all, there are 134 KPIs in this framework. Asset operation management has 23 technical KPIs, listed in Table 1 Maintenance process management has 85 soft KPIs, listed in Table 2, and maintenance resources management has 26 soft KPIs, listed in Table 3.
Asset Management
KPIs
Asset Operation
Management
Maintenance Process
Management
Shutdown Statistics Failure Related
Quantity Related Time Related Resource
Related Cost Related
Quality Effectiveness
Mean Reliability Measures Failure Related
Operational Availability
Mean Maintainability Measures
Maintenance Strategy
Quantity Related Time Related Resource
Related Cost Related
Inventory Management
Contractor Statistics
Maintenance Resources
Management
Skills Management
Workload Management
Training Management
Competence Development
Work Order Approval
Work Order Creation
Work Order Feedback
Overall Asset
Availability
Maintenance Management
Maintenance Planning
Maintenance Preparation
Maintenance Execution
Maintenance Assessment
Spare Parts Management
Outsourcing Management
Human Resources
Management
Reliability
Maintainability
Safety Occupational Safety
Level 1 Level 2 Level 3 Level 4
Figure 1 KPI framework
5 3.
Ass
et O
pera
tion
Man
agem
ent
This
sect
ion
desc
ribe
s ass
et o
pera
tion
man
agem
ent,
incl
udin
g KP
I nam
es, c
onte
xt a
nd p
urpo
ses.
The
KPIs
are
sum
med
up
and
expl
aine
d in
Tab
le 1
.
Tabl
e 1:
Ass
et O
pera
tion
Man
agem
ent K
PIs
Leve
l N
ame
Cont
ext
Purp
ose
3 4
Overall Asset
Shutdown Statistics
Num
ber o
f Shu
tdow
ns
This
is th
e to
tal n
umbe
r of t
imes
the
asse
t is o
ut o
f ser
vice
. H
elps
to u
nder
stan
d th
e nu
mbe
r of t
imes
the
equi
pmen
t, pr
oduc
tion
line
or p
roce
ss u
nit i
s out
of
serv
ice
duri
ng th
e qu
ery
peri
od.
Tota
l Shu
tdow
n Ti
me
This
is th
e to
tal n
umbe
r of h
ours
the
asse
ts a
re o
ut o
f ser
vice
. H
elps
to e
stim
ate
the
tota
l los
s of t
he e
quip
men
t in
term
s of t
ime
duri
ng th
e qu
ery
peri
od.
Aver
age
Shut
dow
n Ti
me
This
is th
e ra
tio o
f tot
al sh
utdo
wn
time
to n
umbe
r of s
hutd
owns
. H
elps
to u
nder
stan
d th
e m
ean
time
of e
ach
shut
dow
n, e
spec
ially
for t
he fa
iled
asse
t.
Failure Related
Dow
ntim
e Ra
tio/F
requ
ency
This
is th
e ra
tio o
f the
num
ber o
f tim
es th
e eq
uipm
ent,
prod
uctio
n lin
e or
pr
oces
s uni
t is n
ot p
rodu
cing
bec
ause
it is
bro
ken,
und
er re
pair
or i
dle
to
the
tota
l pro
duct
ion
time.
Hel
ps to
und
erst
and
the
prop
ortio
n of
the
faile
d as
set i
n th
e to
tal n
umbe
r of s
tops
.
Dow
ntim
e Ra
tio/T
ime
This
is th
e ra
tio o
f the
num
ber o
f hou
rs th
e eq
uipm
ent,
prod
uctio
n lin
e or
pro
cess
uni
t is n
ot p
rodu
cing
bec
ause
it is
bro
ken
dow
n, u
nder
repa
ir
or id
le to
the
tota
l num
ber o
f wor
k ho
urs.
Hel
ps to
und
erst
and
the
prop
ortio
n of
the
faile
d as
set i
n th
e to
tal n
umbe
r of s
tops
in te
rms o
f tim
e.
Failu
re M
ode
Repo
rtin
g Ra
te
This
is th
e am
ount
of c
orre
ctiv
e m
aint
enan
ce w
ork
who
se fa
ilure
mod
e is
kno
wn.
Hel
ps to
und
erst
and
the
prop
ortio
n of
corr
ectiv
e m
aint
enan
ce w
ork
orde
rs w
ith fa
ilure
mod
e in
form
atio
n.
Reas
on fo
r Fai
lure
Re
gist
ratio
n Ra
te
Thi
s is t
he a
mou
nt o
f cor
rect
ive
mai
nten
ance
wor
k w
ith d
escr
iptio
ns.
Hel
ps to
und
erst
and
the
prop
ortio
n of
wor
k or
ders
ent
ered
dur
ing
the
corr
ectiv
e m
aint
enan
ce w
ork
with
info
rmat
ion
on ca
uses
of
failu
re.
Availability
Operational Availability
Avai
labi
lity
This
is th
e as
setβs
abi
lity
to p
erfo
rm a
s and
whe
n re
quir
ed, u
nder
giv
en
cond
ition
s, as
sum
ing
that
the
nece
ssar
y ex
tern
al re
sour
ces a
re p
rovi
ded.
H
elps
to u
nder
stan
d th
e av
aila
bilit
y of
a p
rodu
ct
line
or e
quip
men
t.
6
Reliability
Mean Reliability Measures
Mea
n Ti
me
Betw
een
Failu
re
This
is th
e av
erag
e tim
e be
twee
n fa
ilure
s of r
epai
rabl
e as
sets
and
co
mpo
nent
s.
Hel
ps to
und
erst
and
the
aver
age
time
in b
etw
een
unex
pect
ed b
reak
dow
n of
an
asse
t or p
rodu
ctio
n st
oppa
ges o
f ass
et.
Mea
n Ti
me
To F
ailu
re
This
is th
e av
erag
e tim
e to
failu
re fo
r non
-rep
aira
ble
asse
ts.
Hel
ps to
und
erst
and
the
aver
age
time
that
a
syst
em is
not
faile
d, o
r is a
vaila
ble
Mea
n Up
Tim
e Th
is is
the
mea
n tim
e fr
om th
e sy
stem
(sub
syst
em) r
epai
r to
next
syst
em
(sub
syst
em) f
ailu
re.
Hel
ps to
und
erst
and
the
aver
age
time
duri
ng
whi
ch a
syst
em is
in o
pera
tion.
Failure Related
Emer
genc
y Fa
ilure
Ra
tio
This
is th
e pr
opor
tion
of e
mer
genc
y fa
ilure
s in
the
wor
k or
ders
. H
elps
to u
nder
stan
d th
e pr
opor
tion
of
emer
genc
y fa
ilure
s out
of a
ll fa
ilure
s tha
t hav
e oc
curr
ed.
Emer
genc
y Fa
iled
Equi
pmen
t Rat
io
This
is th
e pr
opor
tion
of fa
iled
asse
ts in
em
erge
ncy
failu
re w
ork
orde
rs.
Hel
ps to
und
erst
and
the
prop
ortio
n of
faile
d as
sets
in e
mer
genc
y fa
ilure
s.
Corr
ectiv
e M
aint
enan
ce F
ailu
re
Rate
Th
is is
the
tota
l num
ber o
f mai
nten
ance
act
ions
on
faile
d as
sets
. H
elps
to u
nder
stan
d th
e fr
eque
ncy
of co
rrec
tive
mai
nten
ance
act
iviti
es.
Repe
at F
ailu
re
This
is th
e to
tal n
umbe
r of m
aint
enan
ce a
ctio
ns o
n fa
ilure
s tha
t occ
ur
mor
e th
an o
ne ti
me.
Hel
ps to
und
erst
and
the
prop
ortio
n of
failu
re
mod
es th
at o
ccur
mor
e th
an o
nce
in th
e to
tal
failu
re.
Maintainability
Mean Maintainability Measures
Mea
n D
ownt
ime
This
is th
e m
ean
time
that
an
equi
pmen
t, pr
oduc
tion
line
or p
roce
ss u
nit
is n
on-o
pera
tiona
l for
reas
ons o
ther
than
repa
ir, s
uch
as m
aint
enan
ce,
and
incl
udes
the
time
from
failu
re to
rest
orat
ion
of a
n as
set o
r co
mpo
nent
.
Hel
ps to
und
erst
and
the
aver
age
tota
l dow
ntim
e re
quir
ed to
rest
ore
an a
sset
to it
s ful
l ope
ratio
nal
capa
bilit
ies.
Mea
n Ti
me
Betw
een
Mai
nten
ance
Th
is is
the
aver
age
leng
th o
f ope
ratin
g tim
e be
twee
n on
e m
aint
enan
ce
actio
n an
d an
othe
r mai
nten
ance
act
ion
for a
com
pone
nt.
Hel
ps to
und
erst
and
the
aver
age
time
that
a
mai
nten
ance
act
ion
requ
ires
to fi
x th
e fa
iled
com
pone
nt o
r the
low
est r
epla
ceab
le u
nit.
Mea
n Ti
me
To
Mai
ntai
n Th
is is
the
aver
age
time
to m
aint
enan
ce.
Hel
ps to
und
erst
and
the
aver
age
mai
nten
ance
du
ratio
n of
equ
ipm
ent.
Mea
n Ti
me
To R
epai
r Th
is is
the
aver
age
time
that
a re
pair
able
or n
on-r
epai
rabl
e as
set a
nd\o
r co
mpo
nent
take
s to
reco
ver f
rom
failu
re.
Hel
ps to
und
erst
and
the
aver
age
time
requ
ired
to
trou
bles
hoot
and
repa
ir fa
iled
equi
pmen
t and
re
turn
it to
nor
mal
ope
ratin
g co
nditi
ons.
Fals
e Al
arm
Rat
e Th
is is
the
prop
ortio
n of
unw
ante
d al
arm
s giv
en in
err
or fo
r an
equi
pmen
t, pr
oduc
tion
line
or p
roce
ss u
nit.
Hel
ps to
und
erst
and
the
num
ber o
f fal
se
posi
tives
that
occ
urre
d fo
r an
asse
t.
7
Safety
Occupational Safety
Num
ber o
f Saf
ety
Inci
dent
s Th
is is
the
tota
l num
ber o
f saf
ety
inci
dent
s tha
t hav
e oc
curr
ed d
urin
g m
aint
enan
ce a
ctiv
ities
. H
elps
to u
nder
stan
d th
e nu
mbe
r of s
afet
y in
cide
nts.
Inju
ry R
atio
Th
is is
the
ratio
of m
aint
enan
ce p
erso
nnel
inju
ries
to to
tal w
ork
hour
s. H
elps
to u
nder
stan
d th
e nu
mbe
r of i
njur
ies t
hat
mai
nten
ance
per
sonn
el su
stai
ned
on th
e jo
b.
Inju
ry R
atio
per
Fa
ilure
Th
is is
the
ratio
of f
ailu
res c
ausi
ng in
juri
es to
the
tota
l num
ber o
f fa
ilure
s.
Hel
ps to
und
erst
and
the
num
ber o
f inj
urie
s tha
t m
aint
enan
ce p
erso
nnel
sust
aine
d co
mpa
red
to
the
tota
l num
ber o
f fai
lure
s.
4. M
aint
enan
ce P
roce
ss M
anag
emen
t
This
sec
tion
desc
ribe
s m
aint
enan
ce p
roce
ss m
anag
emen
t w
hich
dea
ls w
ith K
PIs
that
mea
sure
effi
cien
cy a
nd e
ffect
iven
ess
of t
he c
onsi
sten
t ap
plic
atio
n of
mai
nten
ance
and
mai
nten
ance
supp
ort;
incl
udin
g na
mes
, con
text
and
pur
pose
s. Th
e KP
Is fo
r thi
s lev
el a
re li
sted
and
exp
lain
ed in
Tab
le
2.
Tabl
e 2:
Mai
nten
ance
Pro
cess
Man
agem
ent K
PIs
Leve
l N
ame
Cont
ext
Purp
ose
3 4
Maintenance Management
Maintenance Strategy
Criti
cal E
quip
men
t Rat
io
This
is th
e am
ount
of e
quip
men
t im
port
ant t
o pe
rfor
man
ce,
capa
city
, and
thro
ughp
ut a
nd v
ital t
o op
erat
ion
to a
ll eq
uipm
ent i
n th
e co
mpa
nyβs
plan
t.
Hel
ps to
und
erst
and
the
prop
ortio
n of
cri
tical
equ
ipm
ent i
n th
e pl
ant o
r pro
cess
ing
unit.
Prev
entiv
e M
aint
enan
ce
Rate
This
is th
e pr
opor
tion
of m
aint
enan
ce w
ork
carr
ied
out a
t pr
edet
erm
ined
inte
rval
s or a
ccor
ding
to p
resc
ribe
d cr
iteri
a,
inte
nded
to re
duce
the
prob
abili
ty o
f fai
lure
or d
egra
datio
n of
as
set.
Hel
ps to
und
erst
and
the
prop
ortio
n of
equ
ipm
ent w
ith a
pr
oact
ive
mai
nten
ance
stra
tegy
in th
e pl
ant o
r pro
cess
ing
unit.
Pred
ictiv
e M
aint
enan
ce
(PdM
) Rat
e
This
is th
e pr
opor
tion
of co
nditi
on-b
ased
mai
nten
ance
carr
ied
out f
ollo
win
g a
fore
cast
der
ived
from
repe
ated
ana
lysi
s or
know
n ch
arac
teri
stic
s and
eva
luat
ion
of th
e si
gnifi
cant
pa
ram
eter
s of d
egra
ding
ass
et.
Hel
ps to
und
erst
and
the
prop
ortio
n of
equ
ipm
ent w
ith a
pr
edic
tive
mai
nten
ance
pol
icy
in th
e pl
ant o
r pro
cess
ing
unit.
Prev
entiv
e M
aint
enan
ce
Rate
(Cri
tical
Eq
uipm
ent)
This
is th
e pr
opor
tion
of m
aint
enan
ce ca
rrie
d ou
t at
pred
eter
min
ed in
terv
als o
r acc
ordi
ng to
pre
scri
bed
crite
ria,
in
tend
ed to
redu
ce th
e pr
obab
ility
of f
ailu
re o
r deg
rada
tion
of
the
asse
t.
Hel
ps to
und
erst
and
the
prop
ortio
n of
cri
tical
equ
ipm
ent
with
a p
roac
tive
mai
nten
ance
stra
tegy
in th
e pl
ant o
r pr
oces
sing
uni
t.
Pred
ictiv
e M
aint
enan
ce
Rate
(Cri
tical
Eq
uipm
ent)
This
is th
e pr
opor
tion
of co
nditi
on-b
ased
mai
nten
ance
carr
ied
out f
ollo
win
g a
fore
cast
der
ived
from
repe
ated
ana
lysi
s or
know
n ch
arac
teri
stic
s and
eva
luat
ion
of th
e si
gnifi
cant
Hel
ps to
und
erst
and
the
prop
ortio
n of
cri
tical
equ
ipm
ent
with
a p
redi
ctiv
e m
aint
enan
ce p
olic
y in
the
plan
t or
proc
essi
ng u
nit.
8
pa
ram
eter
s of t
he d
egra
ding
ass
et.
Run
to F
ailu
re (R
TF)
Ratio
for C
ritic
al
Equi
pmen
t
This
is th
e ra
tio o
f fai
lure
man
agem
ent p
olic
y fo
r cri
tical
eq
uipm
ent w
ithou
t any
att
empt
to a
ntic
ipat
e or
pre
vent
failu
re
to a
ll po
licy
for c
ritic
al e
quip
men
t.
Hel
ps to
und
erst
and
the
prop
ortio
n of
cri
tical
equ
ipm
ent
that
doe
s not
hav
e an
y pr
ecau
tiona
ry o
r pre
dict
ive
mai
nten
ance
pol
icy
in th
e pl
ant o
r pro
cess
ing
unit.
Pl
anne
d M
aint
enan
ce v
s Un
plan
ned
Mai
nten
ance
Th
is is
the
ratio
of p
lann
ed m
aint
enan
ce to
unp
lann
ed
mai
nten
ance
. H
elps
to u
nder
stan
d th
e re
latio
nshi
p be
twee
n pl
anne
d m
aint
enan
ce a
nd u
npla
nned
mai
nten
ance
.
Maintenance Planning
Quantity Related
Num
ber o
f Pla
nned
W
ork
Orde
rs C
reat
ed
This
is th
e to
tal n
umbe
r of w
ork
orde
rs th
at h
ave
been
sc
hedu
led.
H
elps
to u
nder
stan
d th
e pl
anne
d am
ount
of s
ched
uled
m
aint
enan
ce/m
aint
enan
ce w
ork.
Time Related
Aver
age
Plan
ned
Exec
utio
n Ti
me
This
is th
e m
ean
exec
utio
n tim
e of
all
plan
ned
wor
k or
ders
. H
elps
to u
nder
stan
d th
e av
erag
e pl
anne
d ex
ecut
ion
time
of
plan
ned
mai
nten
ance
/mai
nten
ance
wor
k.
Resource Related
Tota
l Num
ber o
f Pl
anne
d In
tern
al L
abou
r H
ours
This
is th
e su
m o
f lab
our h
ours
att
ribu
ted
to p
lann
ed
mai
nten
ance
wor
k do
ne b
y in
tern
al m
aint
enan
ce p
erso
nnel
. H
elps
to u
nder
stan
d th
e pl
anne
d m
an-h
ours
requ
ired
for
plan
ned
inte
rnal
mai
nten
ance
.
Aver
age
Plan
ned
Inte
rnal
Lab
our H
ours
Th
is is
the
mea
n ho
urs f
or p
lann
ed in
tern
al la
bour
. H
elps
to u
nder
stan
d th
e m
ean
man
-hou
rs re
quir
ed fo
r pl
anne
d in
tern
al m
aint
enan
ce.
Tota
l Num
ber o
f Pl
anne
d Ex
tern
al L
abou
r H
ours
This
is th
e su
m o
f lab
our h
ours
att
ribu
ted
to p
lann
ed
mai
nten
ance
wor
k by
ext
erna
l mai
nten
ance
per
sonn
el.
Hel
ps to
und
erst
and
the
plan
ned
labo
ur h
ours
requ
ired
for
mai
nten
ance
wor
k by
ext
erna
l mai
nten
ance
per
sonn
el.
Aver
age
Plan
ned
Exte
rnal
Lab
our H
ours
Th
is is
the
mea
n la
bour
hou
rs fo
r pla
nned
ext
erna
l lab
our.
Hel
ps to
und
erst
and
the
aver
age
time
requ
ired
for p
lann
ed
mai
nten
ance
by
exte
rnal
mai
nten
ance
per
sonn
el.
Plan
ned
Num
ber o
f M
ater
ial U
sed
This
is th
e su
m o
f all
mat
eria
ls sc
hedu
led
to b
e us
ed fo
r m
aint
enan
ce a
nd/o
r mai
nten
ance
wor
k.
Hel
ps to
und
erst
and
the
num
ber o
f spa
re p
arts
use
d in
the
plan
ned
mai
nten
ance
. Av
erag
e Pl
anne
d N
umbe
r of M
ater
ials
Us
ed
This
is th
e m
ean
num
ber o
f mat
eria
ls to
be
used
for s
ched
uled
m
aint
enan
ce a
nd/o
r mai
nten
ance
wor
k.
Hel
ps to
und
erst
and
the
aver
age
num
ber o
f spa
re p
arts
us
ed fo
r pla
nned
mai
nten
ance
.
Cost Related
Tota
l Cos
t of P
lann
ed
Hum
an R
esou
rces
Th
is is
the
tota
l cos
t of m
anpo
wer
use
d fo
r sch
edul
ed
mai
nten
ance
and
/or m
aint
enan
ce w
ork.
H
elps
to u
nder
stan
d th
e m
anpo
wer
cost
of p
lann
ed
mai
nten
ance
. Av
erag
e Pl
anne
d Ex
tern
al H
uman
Re
sour
ce C
osts
This
is th
e m
ean
exte
rnal
man
pow
er co
st fo
r sch
edul
ed
mai
nten
ance
and
/or m
aint
enan
ce w
ork.
H
elps
to u
nder
stan
d th
e av
erag
e pl
anne
d m
anpo
wer
cost
of
exte
rnal
labo
ur fo
r pla
nned
mai
nten
ance
.
Tota
l Cos
t of P
lann
ed
Mat
eria
ls
This
is th
e to
tal c
ost o
f mat
eria
ls n
eede
d fo
r sch
edul
ed
mai
nten
ance
and
/or m
aint
enan
ce w
ork.
H
elps
to u
nder
stan
d th
e co
st o
f mat
eria
ls fo
r pla
nned
m
aint
enan
ce.
9
Plan
ned
Aver
age
Mat
eria
l Cos
t Th
is is
the
mea
n co
st o
f mat
eria
ls fo
r sch
edul
ed m
aint
enan
ce
and/
or m
aint
enan
ce w
ork.
H
elps
to u
nder
stan
d th
e m
ean
plan
ned
cost
of m
ater
ials
for
each
sche
dule
d re
pair
or m
aint
enan
ce a
ctiv
ity.
Labo
ur C
ost R
atio
Th
is is
the
ratio
of m
anpo
wer
cost
to th
e to
tal c
ost o
f pla
nned
m
aint
enan
ce.
Hel
ps to
und
erst
and
the
ratio
of m
anpo
wer
cost
to to
tal
plan
ned
cost
in p
lann
ed m
aint
enan
ce.
Plan
ned
Mat
eria
l Cos
t Ra
tio
This
is th
e ra
tio o
f pla
nned
mat
eria
l cos
t to
the
plan
ned
tota
l co
st o
f mai
nten
ance
. H
elps
to u
nder
stan
d th
e pr
opor
tion
of th
e to
tal c
osts
of
plan
ned
mat
eria
l allo
cate
d to
pla
nned
mai
nten
ance
.
Maintenance Preparation
Work Order Creation
Plan
ned
Star
t / E
nd
Tim
e Re
gist
ratio
n Ra
te
This
is th
e ra
tio o
f wor
k or
ders
who
se p
lann
ed st
art/
end
tim
e is
kno
wn
at th
e tim
e of
crea
tion
to th
e to
tal w
ork
orde
rs
crea
ted.
Hel
ps to
und
erst
and
the
amou
nt o
f wor
k or
ders
who
se
plan
ned
star
t and
end
tim
e ar
e pr
ovid
ed d
urin
g th
eir
crea
tion.
Plan
ned
Spar
e Pa
rts
Regi
stra
tion
Rate
This
is th
e ra
tio o
f wor
k or
der w
hose
spar
e pa
rts r
equi
rem
ent
are
know
n at
the
time
of th
e w
ork
orde
r cre
atio
n to
the
tota
l w
ork
orde
rs cr
eate
d.
Hel
ps to
kno
w th
e pl
anne
d sp
are
part
s reg
istr
atio
n ra
te o
f w
ork
orde
rs.
Plan
ned
Man
-Hou
r Re
gist
ratio
n Ra
te
This
is th
e nu
mbe
r of w
ork
orde
rs w
ith la
bour
hou
rs n
eede
d re
cord
ed d
urin
g w
ork
orde
r cre
atio
n ou
t of a
ll th
e w
ork
orde
rs
crea
ted.
Hel
ps to
und
erst
and
the
prop
ortio
n of
wor
k or
ders
with
th
e re
quir
ed la
bour
regi
ster
ed d
urin
g w
ork
orde
r cre
atio
n.
Plan
ned
Dow
ntim
e Re
gist
ratio
n Ra
te
This
is th
e ra
tio o
f hou
rs th
at th
e pl
ant o
r ass
et w
ill b
e do
wn
ahea
d of
tim
e to
the
tota
l wor
k ho
urs.
Hel
ps to
und
erst
and
the
perc
enta
ge o
f wor
k or
ders
that
w
ere
ente
red
for p
lann
ed d
ownt
ime
duri
ng w
ork
orde
r cr
eatio
n.
Stan
dard
Ope
ratin
g Pl
an
Regi
stra
tion
Rate
Th
is is
ratio
of t
he n
umbe
r of w
ork
orde
rs w
ith a
n SO
P to
the
tota
l wor
k or
ders
. H
elps
to u
nder
stan
d th
e pr
opor
tion
of w
ork
orde
rs w
ith
stan
dard
ope
ratin
g pr
oced
ure
plan
s.
Plan
ned
Wor
k Ty
pe
Regi
stra
tion
Rate
Th
is is
the
prop
ortio
n of
wor
k or
ders
with
requ
ired
skill
s re
gist
ered
dur
ing
thei
r cre
atio
n.
Hel
ps to
und
erst
and
the
prop
ortio
n of
wor
k or
ders
with
kn
own
skill
s req
uire
d in
the
wor
k ca
tego
ry.
Job
Prio
rity
Reg
istr
atio
n Ra
te
This
is th
e nu
mbe
r of w
ork
orde
rs w
ith jo
b pr
iori
ties a
ssig
ned
duri
ng th
e w
ork
orde
r cre
atio
n ou
t of a
ll th
e w
ork
orde
rs.
Hel
ps to
und
erst
and
the
prop
ortio
n of
wor
k or
ders
as
sign
ed w
ork
prio
ritie
s dur
ing
wor
k or
der c
reat
ion.
Work Order Feedback
Actu
al S
pare
Par
ts U
se
Regi
stra
tion
Rate
Th
is is
the
amou
nt o
f spa
re p
arts
use
d fo
r mai
nten
ance
wor
k.
Hel
ps to
und
erst
and
the
actu
al u
se o
f spa
re p
arts
for
mai
nten
ance
jobs
.
Actu
al M
an-H
our
Regi
stra
tion
Rate
Th
is is
the
prop
ortio
n of
labo
ur u
sed
for m
aint
enan
ce w
ork.
H
elps
to u
nder
stan
d th
e am
ount
of l
abou
r use
d fo
r m
aint
enan
ce ta
sks.
Actu
al D
ownt
ime
Regi
stra
tion
Rate
Th
is is
the
num
ber o
f wor
k or
ders
caus
ing
actu
al d
ownt
ime.
H
elps
to u
nder
stan
d th
e pr
opor
tion
of w
ork
orde
rs th
at
lead
to d
ownt
ime.
Wor
k Or
der R
egis
trat
ion
Back
-Log
Th
is is
the
diffe
renc
e be
twee
n w
ork
orde
r reg
istr
atio
n da
te a
nd
the
actu
al re
gist
ratio
n da
te o
f the
wor
k or
der.
Hel
ps to
und
erst
and
the
time
inte
rval
bet
wee
n th
e co
mpl
etio
n of
the
wor
k or
der a
nd th
e co
mpl
etio
n of
re
gist
ratio
n in
the
syst
em.
10
Work Order Approval
Tota
l Num
ber o
f Wor
k Or
ders
Th
is is
the
sum
of p
ropo
sed
wor
k or
ders
that
hav
e be
en
regi
ster
ed.
Hel
ps to
und
erst
and
the
tota
l num
ber o
f wor
k or
ders
re
port
ed.
Tota
l Num
ber o
f Ap
prov
ed W
ork
Orde
rs
This
is th
e su
m o
f pro
pose
d w
ork
orde
rs th
at h
ave
been
ap
prov
ed.
Hel
ps to
und
erst
and
the
tota
l num
ber o
f wor
k or
ders
ap
prov
ed in
a si
ngle
pas
s. To
tal N
umbe
r of
Unap
prov
ed W
ork
Orde
rs
This
is th
e su
m o
f pro
pose
d w
ork
orde
rs th
at h
ave
not b
een
appr
oved
.
Hel
ps to
und
erst
and
the
tota
l num
ber o
f wor
k or
ders
not
ap
prov
ed in
a si
ngle
pas
s.
Wor
k Or
der A
ppro
val
Ratio
Th
is is
the
ratio
of p
ropo
sed
wor
k or
ders
to p
lann
ed w
ork
orde
rs.
Hel
ps to
und
erst
and
the
prop
ortio
n of
repo
rted
wor
k or
ders
aga
inst
the
tota
l pla
nned
wor
k or
ders
. On
e-tim
e Ap
prov
ed
Wor
k Or
der R
atio
This
is th
e ra
tio o
f wor
k or
ders
pro
posa
ls th
at w
ere
appr
oved
on
ce to
act
ual w
ork
orde
rs.
Hel
ps to
und
erst
and
the
rate
of o
ne-t
ime
appr
oval
s for
w
ork
orde
rs su
bmitt
ed.
Aver
age
time
lag
for
Repo
rtin
g an
d Ap
prov
ing
Wor
k Or
ders
This
is th
e di
ffere
nce
betw
een
appr
oved
wor
k or
ders
and
pr
opos
ed w
ork
orde
rs.
Hel
ps to
und
erst
and
the
aver
age
time
betw
een
subm
issi
on
of a
wor
k or
der a
nd th
e ap
prov
al o
f the
issu
ance
of t
he
wor
k or
der.
Maintenance Execution
Quantity Related
Num
ber o
f Pla
nned
W
ork
Orde
rs C
ompl
eted
Th
is is
the
tota
l num
ber o
f pre
vent
ive
mai
nten
ance
wor
k or
ders
that
hav
e be
en re
solv
ed.
Hel
ps to
und
erst
and
the
plan
ned
mai
nten
ance
wor
k do
ne.
Num
ber o
f Unp
lann
ed
Wor
k Or
ders
Com
plet
ed
This
is th
e to
tal n
umbe
r of u
npla
nned
corr
ectiv
e w
ork
orde
rs
that
hav
e be
en re
solv
ed.
Hel
ps to
und
erst
and
the
amou
nt o
f unp
lann
ed m
aint
enan
ce
wor
k co
mpl
eted
. N
umbe
r of W
ork
Orde
rs
Com
plet
ed P
er S
hift
This
is th
e to
tal n
umbe
r of w
ork
orde
rs co
mpl
eted
per
shift
. H
elps
to u
nder
stan
d th
e nu
mbe
r of w
ork
orde
rs co
mpl
eted
in
a sh
ift.
Wor
k Or
der R
esol
utio
n Ra
te
This
is th
e ra
tio o
f the
num
ber o
f wor
k or
ders
per
form
ed a
s sc
hedu
led
to th
e to
tal n
umbe
r of s
ched
uled
wor
k or
ders
. H
elps
to u
nder
stan
d th
e ra
tio o
f the
num
ber o
f wor
k or
ders
co
mpl
eted
as s
ched
uled
.
Time Related
Aver
age
Wor
k Or
der
Tim
e Th
is is
the
mea
n ex
ecut
ion
time
for c
ompl
eted
wor
k or
ders
. H
elps
to u
nder
stan
d th
e av
erag
e ex
ecut
ion
time
of
com
plet
ed m
aint
enan
ce w
ork.
Av
erag
e W
aitin
g Ti
me
for P
erso
nnel
Th
is is
the
mea
n w
aitin
g tim
e fo
r mai
nten
ance
per
sonn
el
need
ed to
reso
lve
a m
aint
enan
ce re
ques
t. H
elps
to u
nder
stan
d th
e av
erag
e lo
gist
ical
wai
ting
time
for
mai
nten
ance
staf
f for
com
plet
ed m
aint
enan
ce w
ork.
Av
erag
e W
aitin
g Ti
me
for S
pare
Par
ts
This
is th
e m
ean
wai
ting
time
for s
pare
par
ts u
sed
for
com
plet
ed m
aint
enan
ce w
ork.
H
elps
to u
nder
stan
d th
e w
aitin
g tim
e fo
r spa
re p
arts
for
mai
nten
ance
wor
k.
Pers
onne
l Wai
ting
Tim
e Ra
tio
This
is th
e pr
opor
tion
of ti
me
it ta
kes t
o ge
t mai
nten
ance
pe
rson
nel t
o re
solv
e a
mai
nten
ance
task
. H
elps
to u
nder
stan
d th
e st
aff w
aitin
g tim
e fo
r mai
nten
ance
w
ork
com
plet
ed.
Spar
e Pa
rts W
aitin
g Ti
me
Ratio
Th
is is
the
prop
ortio
nal w
aitin
g tim
e fo
r spa
re p
arts
use
d fo
r m
aint
enan
ce w
ork.
H
elps
to u
nder
stan
d th
e sp
are
part
s wai
ting
time
for
com
plet
ed m
aint
enan
ce w
ork.
Av
erag
e M
aint
enan
ce
Outa
ge T
ime
This
is th
e pe
riod
of t
ime
that
the
asse
t fai
ls to
pro
vide
or
perf
orm
its p
rim
ary
func
tion
duri
ng m
aint
enan
ce w
ork.
H
elps
to u
nder
stan
d th
e av
erag
e ex
ecut
ion
time
of th
e m
aint
enan
ce w
ork.
Av
erag
e W
aitin
g Ti
me
of
Pers
onne
l dur
ing
This
is th
e m
ean
wai
ting
time
for m
aint
enan
ce p
erso
nnel
du
ring
shut
dow
n.
Hel
ps to
und
erst
and
the
aver
age
logi
stic
wai
ting
time
for
mai
nten
ance
per
sonn
el fo
r mai
nten
ance
wor
k du
ring
11
Shut
dow
n sh
utdo
wn.
Av
erag
e W
aitin
g Ti
me
for S
pare
Par
ts d
urin
g Sh
utdo
wn
This
is th
e m
ean
wai
ting
time
of w
aitin
g fo
r spa
re p
arts
dur
ing
shut
dow
n.
Hel
ps to
und
erst
and
the
aver
age
wai
ting
time
for s
pare
pa
rts u
sed
for c
ompl
etin
g m
aint
enan
ce w
ork
at sh
utdo
wn.
Aver
age
Wai
ting
Tim
e of
Pe
rson
nel d
urin
g Sh
utdo
wn
Ratio
This
is th
e m
ean
wai
ting
time
for m
aint
enan
ce p
erso
nnel
to
mea
n m
aint
enan
ce o
utag
e tim
e du
ring
shut
dow
n.
Hel
ps to
und
erst
and
the
ratio
of w
aitin
g tim
e fo
r per
sonn
el
who
hav
e co
mpl
eted
the
mai
nten
ance
wor
k at
shut
dow
n to
th
e to
tal r
epai
r tim
e.
Aver
age
Wai
ting
Tim
e fo
r Spa
re P
arts
dur
ing
Shut
dow
n Ra
tio
This
is th
e m
ean
wai
ting
time
for s
pare
par
ts to
the
mea
n m
aint
enan
ce o
utag
e tim
e.
Hel
ps to
und
erst
and
the
prop
ortio
n of
spar
e pa
rts w
aitin
g tim
e fo
r the
repa
ir/m
aint
enan
ce w
ork
to to
tal m
aint
enan
ce
outa
ge ti
me
duri
ng th
e qu
ery
peri
od.
Estim
ated
Tim
e vs
. Ac
tual
Tim
e Th
is is
the
diffe
renc
e be
twee
n ac
tual
mai
nten
ance
tim
e an
d pl
anne
d m
aint
enan
ce ti
me.
H
elps
to u
nder
stan
d th
e tim
e va
rian
ces i
n w
ork
orde
r.
Resource Related
Tota
l Num
ber o
f In
tern
al L
abou
r Hou
rs
This
is th
e su
m o
f hou
rs u
sed
by in
-hou
se m
aint
enan
ce
pers
onne
l for
mai
nten
ance
wor
k.
Hel
ps to
und
erst
and
the
tota
l num
ber o
f hou
rs u
sed
by in
-ho
use
mai
nten
ance
per
sonn
el fo
r mai
nten
ance
wor
k pe
rfor
med
. Av
erag
e In
tern
al L
abou
r H
ours
Use
d Th
is is
the
mea
n nu
mbe
r of h
ours
use
d by
in-h
ouse
m
aint
enan
ce p
erso
nnel
for m
aint
enan
ce w
ork.
H
elps
to u
nder
stan
d th
e av
erag
e la
bour
hou
rs u
sed
for e
ach
com
plet
ed in
tern
al m
aint
enan
ce w
ork.
To
tal N
umbe
r of
Exte
rnal
Lab
our H
ours
This
is th
e su
m o
f hou
rs u
sed
by m
aint
enan
ce co
ntra
ctor
s for
m
aint
enan
ce w
ork.
H
elps
to u
nder
stan
d th
e la
bour
hou
rs u
sed
for e
xter
nal
mai
nten
ance
wor
k.
Aver
age
Exte
rnal
Lab
our
Hou
rs U
sed
This
is th
e m
ean
hour
s use
d by
ext
erna
l mai
nten
ance
pe
rson
nel f
or m
aint
enan
ce w
ork.
H
elps
to u
nder
stan
d th
e av
erag
e la
bour
hou
rs fo
r eac
h co
mpl
eted
ext
erna
l mai
nten
ance
act
ion.
N
umbe
r of M
ater
ials
Us
ed
This
is th
e to
tal n
umbe
r of s
pare
par
ts u
sed
for m
aint
enan
ce
wor
k.
Hel
ps to
und
erst
and
the
actu
al n
umbe
r of s
pare
par
ts u
sed
for m
aint
enan
ce w
ork.
Aver
age
Mat
eria
ls U
sed
This
is th
e m
ean
spar
e pa
rts u
sed
for m
aint
enan
ce w
ork.
H
elps
to u
nder
stan
d th
e av
erag
e nu
mbe
r of s
pare
par
ts
used
for e
ach
com
plet
ed m
aint
enan
ce a
ctio
n.
Cost Related
Tota
l Cos
t of E
xter
nal
Hum
an R
esou
rces
Use
d Th
is is
the
tota
l cos
t of u
sing
mai
nten
ance
cont
ract
ors f
or
mai
nten
ance
wor
k.
Hel
ps to
und
erst
and
the
cost
of e
xter
nal l
abou
r for
co
mpl
eted
mai
nten
ance
wor
k.
Aver
age
Exte
rnal
H
uman
Res
ourc
es C
osts
Th
is is
the
mea
n co
st o
f ext
erna
l mai
nten
ance
cont
ract
ors f
or
mai
nten
ance
wor
k.
Hel
ps to
und
erst
and
the
aver
age
exte
rnal
labo
ur co
sts u
sed
for m
aint
enan
ce w
ork
com
plet
ed.
Tota
l Cos
t of M
ater
ials
Us
ed
This
is th
e to
tal c
ost o
f mat
eria
ls u
sed
for m
aint
enan
ce.
Hel
ps to
und
erst
and
the
cost
of m
ater
ials
use
d fo
r m
aint
enan
ce w
ork
com
plet
ed.
Aver
age
Cost
of
Mat
eria
ls U
sed
This
is th
e m
ean
cost
of m
ater
ials
use
d fo
r mai
nten
ance
wor
k.
Hel
ps to
und
erst
and
the
aver
age
cost
of m
ater
ials
for
com
plet
ed m
aint
enan
ce w
ork.
Ex
tern
al L
abou
r Cos
ts
Ratio
Th
is is
the
ratio
of t
he to
tal e
xter
nal m
aint
enan
ce co
ntra
ctor
co
st to
the
tota
l mai
nten
ance
cost
. H
elps
to u
nder
stan
d th
e co
st o
f man
pow
er co
st to
tota
l cos
t of
mai
nten
ance
wor
k co
mpl
eted
12
Actu
al M
ater
ials
Cos
t Ra
tio
This
is th
e ra
tio o
f cos
ts fo
r mat
eria
ls to
the
tota
l mai
nten
ance
co
st.
Hel
ps to
und
erst
and
the
cost
of t
he m
ater
ials
use
d to
co
mpl
ete
the
mai
nten
ance
wor
k.
Mai
nten
ance
Cos
t per
As
set
This
is th
e to
tal c
ost i
ncur
red
for m
aint
aini
ng a
n as
set.
Hel
ps to
und
erst
and
the
cost
incu
rred
for m
aint
enan
ce
wor
k.
Maintenance Assessment
Quality
Num
ber o
f Com
plet
ed
Wor
k Or
ders
App
rove
d Th
is is
the
tota
l num
ber o
f com
plet
ed w
ork
orde
rs th
at h
ave
been
app
rove
d af
ter r
esol
utio
n.
Hel
ps to
und
erst
and
the
tota
l num
ber o
f rep
orte
d ap
prov
als f
or co
mpl
eted
wor
k or
ders
. W
ork
Orde
r App
rova
l Ra
tio
This
is th
e ra
tio o
f com
plet
ed w
ork
orde
rs th
at n
eed
to b
e ap
prov
ed a
fter r
esol
utio
n to
tota
l com
plet
ed w
ork
orde
rs.
Hel
ps to
und
erst
and
the
prop
ortio
n of
the
wor
k or
ders
that
ne
ed to
be
subm
itted
for a
ppro
val.
One-
Tim
e Pa
ss In
tern
al
Com
plet
ion
Rate
This
is th
e ra
tio o
f wor
k or
ders
that
are
reso
lved
the
very
firs
t tim
e th
ey o
ccur
by
inte
rnal
mai
nten
ance
per
sonn
el to
tota
l co
mpl
eted
wor
k or
ders
.
Hel
ps to
und
erst
and
the
num
ber o
f one
-tim
e w
ork
orde
rs
by in
tern
al m
aint
enan
ce p
erso
nnel
that
do
not n
eed
to b
e re
wor
ked.
One-
Tim
e Pa
ss E
xter
nal
Com
plet
ion
Rate
This
is th
e ra
tio o
f wor
k or
ders
that
are
reso
lved
the
very
firs
t tim
e th
ey o
ccur
by
exte
rnal
mai
nten
ance
per
sonn
el to
tota
l co
mpl
eted
wor
k or
ders
.
Hel
ps to
und
erst
and
the
num
ber o
f one
-tim
e w
ork
orde
rs
by e
xter
nal m
aint
enan
ce p
erso
nnel
that
do
not n
eed
to b
e re
wor
ked.
Plan
ning
Com
plia
nce
This
is a
mea
sure
of a
dher
ence
to m
aint
enan
ce p
lans
. H
elps
to u
nder
stan
d th
e am
ount
of p
lann
ed m
aint
enan
ce
wor
k th
at is
star
ted
on th
e sa
me
date
as p
lann
ed co
mpa
red
to im
plem
enta
tion
and
eval
uatio
n pl
ans.
Effectiveness
Inte
rnal
Wor
k Co
mpl
etio
n Ra
te
This
is th
e ra
tio o
f suc
cess
ful w
ork
com
plet
ed b
y in
tern
al
mai
nten
ance
per
sonn
el to
tota
l com
plet
ed w
ork.
H
elps
to u
nder
stan
d th
e pr
opor
tion
of w
ork
orde
rs
com
plet
ed b
y in
tern
al m
aint
enan
ce p
erso
nnel
. Ou
tsou
rced
Wor
k Co
mpl
etio
n Ra
te
This
is th
e ra
tio o
f suc
cess
ful w
ork
com
plet
ion
by e
xter
nal
mai
nten
ance
per
sonn
el to
tota
l com
plet
ed w
ork.
H
elps
to u
nder
stan
d th
e pr
opor
tion
of w
ork
orde
rs
com
plet
ed b
y ex
tern
al m
aint
enan
ce p
erso
nnel
. In
tern
al W
ork
Dela
y Ra
te
This
is th
e ra
tio o
f del
ayed
mai
nten
ance
wor
k by
inte
rnal
m
aint
enan
ce p
erso
nnel
to a
ll in
tern
al m
aint
enan
ce.
Hel
ps to
und
erst
and
com
plet
ion
dela
ys in
inte
rnal
m
aint
enan
ce w
ork.
Inte
rnal
Wor
k Av
erag
e De
lay
Peri
od
This
is th
e m
ean
peri
od o
f del
ayed
wor
k by
inte
rnal
m
aint
enan
ce p
erso
nnel
.
Hel
ps to
und
erst
and
the
aver
age
dela
y pe
riod
of t
he w
ork
orde
rs sc
hedu
led
to b
e co
mpl
eted
by
inte
rnal
mai
nten
ance
pe
rson
nel.
Exte
rnal
Wor
k D
elay
Ra
te
This
is th
e ra
tio o
f del
ayed
mai
nten
ance
wor
k by
ext
erna
l m
aint
enan
ce p
erso
nnel
to a
ll ex
tern
al w
ork.
H
elps
to u
nder
stan
d th
e de
laye
d co
mpl
etio
n of
ext
erna
l w
ork.
Exte
rnal
Wor
k Av
erag
e De
lay
Peri
od
This
is th
e m
ean
peri
od o
f del
ayed
wor
k by
ext
erna
l m
aint
enan
ce p
erso
nnel
.
Hel
ps to
und
erst
and
the
aver
age
dela
y pe
riod
of t
he w
ork
orde
rs sc
hedu
led
to b
e co
mpl
eted
by
exte
rnal
mai
nten
ance
pe
rson
nel.
Inte
rnal
Ave
rage
Ex
ecut
ion
Tim
e De
viat
ion
Ratio
This
is th
e di
ffere
nce
in ti
me
betw
een
plan
ned
and
actu
al
mai
nten
ance
jobs
don
e by
inte
rnal
mai
nten
ance
per
sonn
el.
Hel
ps to
und
erst
and
the
diffe
renc
e be
twee
n th
e av
erag
e ex
ecut
ion
time
of th
e in
tern
al m
aint
enan
ce w
ork
and
the
plan
. Ex
tern
al C
omm
ittee
Ex
ecut
ion
Tim
e De
viat
ion
Ratio
This
is th
e di
ffere
nce
in ti
me
betw
een
plan
ned
and
actu
al
mai
nten
ance
jobs
don
e by
ext
erna
l mai
nten
ance
per
sonn
el
Hel
ps to
und
erst
and
the
diffe
renc
e be
twee
n th
e av
erag
e ex
ecut
ion
time
and
plan
of t
he e
xter
nal m
aint
enan
ce w
ork
com
plet
ed.
13
Inte
rnal
Man
-Hou
r Di
ffere
nce
Ratio
Th
is is
the
diffe
renc
e in
tim
e be
twee
n pl
anne
d an
d ac
tual
la
bour
hou
rs u
sed
by in
tern
al m
aint
enan
ce p
erso
nnel
. H
elps
to u
nder
stan
d th
e de
viat
ions
from
the
plan
ned
labo
ur u
sed
for i
nter
nal m
aint
enan
ce w
ork.
Inte
rnal
Ave
rage
Man
-H
our D
iffer
ence
Rat
io
This
is th
e m
ean
diffe
renc
e in
tim
e be
twee
n pl
anne
d an
d ac
tual
la
bour
hou
rs u
sed
by in
tern
al m
aint
enan
ce p
erso
nnel
.
Hel
ps to
und
erst
and
the
aver
age
devi
atio
n fr
om th
e pl
anne
d av
erag
e fo
r eac
h co
mpl
eted
inte
rnal
mai
nten
ance
ac
tion.
Ex
tern
al M
an-H
our
Diffe
renc
e Ra
tio
This
is th
e di
ffere
nce
in ti
me
betw
een
plan
ned
and
actu
al
labo
ur h
ours
of e
xter
nal m
aint
enan
ce p
erso
nnel
. H
elps
to u
nder
stan
d th
e de
viat
ion
betw
een
actu
al a
nd
plan
ned
labo
ur h
ours
of
exte
rnal
mai
nten
ance
wor
k.
Exte
rnal
Ave
rage
Man
-H
our D
iffer
ence
Rat
io
This
is th
e m
ean
diffe
renc
e in
tim
e be
twee
n pl
anne
d an
d ac
tual
la
bour
hou
rs o
f ext
erna
l mai
nten
ance
per
sonn
el.
Hel
ps to
und
erst
and
the
aver
age
devi
atio
n fr
om th
e pl
anne
d av
erag
e fo
r eac
h ex
tern
al m
aint
enan
ce a
ctio
n.
Mat
eria
l Diff
eren
ce
Ratio
Th
is is
the
diffe
renc
e be
twee
n pl
anne
d sp
are
part
s and
act
ual
spar
e pa
rts u
sed
for m
aint
enan
ce w
ork.
Hel
ps to
und
erst
and
the
diffe
renc
e be
twee
n th
e ac
tual
nu
mbe
r of s
pare
par
ts u
sed
for m
aint
enan
ce w
ork
and
the
num
ber o
f spa
re p
arts
ass
igne
d in
the
plan
.
Aver
age
Mat
eria
l Di
ffere
nce
Ratio
Th
is is
the
mea
n di
ffere
nce
betw
een
plan
ned
spar
e pa
rts a
nd
actu
al sp
are
part
s use
d fo
r mai
nten
ance
wor
k.
Hel
ps to
und
erst
and
the
diffe
renc
e be
twee
n th
e av
erag
e nu
mbe
r of u
sed
spar
e pa
rts a
nd th
e pl
anne
d av
erag
e fo
r ea
ch co
mpl
eted
mai
nten
ance
act
ion.
5. M
aint
enan
ce R
esou
rces
Man
agem
ent
This
sec
tion
desc
ribe
s Le
vel
III,
mai
nten
ance
res
ourc
es m
anag
emen
t, w
hich
dea
ls w
ith K
PIs
that
mea
sure
spa
re p
art
man
agem
ent,
inte
rnal
m
aint
enan
ce p
erso
nnel
man
agem
ent a
nd e
xter
nal m
aint
enan
ce p
erso
nnel
man
agem
ent;
incl
udin
g KP
I nam
es, c
onte
xt a
nd p
urpo
ses.
The
KPIs
are
lis
ted
and
expl
aine
d in
Tab
le 3
.
Tabl
e 3:
Mai
nten
ance
Res
ourc
es M
anag
emen
t KPI
s
Leve
l N
ame
Cont
ext
Purp
ose
3 4
Spare Parts Management
Inventory Management
Aver
age
Spar
e Pa
rt Q
uant
ity
This
is th
e m
ean
num
ber o
f spa
re p
arts
in st
ock.
H
elps
to k
now
the
aver
age
num
ber o
f spa
re p
arts
be
twee
n op
enin
g an
d cl
osin
g st
ocks
Spar
e Pa
rt C
apita
l Util
izat
ion
This
is th
e m
ean
cost
of s
pare
par
ts u
tiliz
atio
n.
Hel
ps to
und
erst
and
the
aver
age
inve
ntor
y va
lue
of u
sing
spar
e pa
rts c
ompa
red
to th
e or
igin
al
purc
hase
cost
of t
he e
quip
men
t. Sp
are
Part
s Cap
ital
Repl
acem
ent R
ate
This
is th
e av
erag
e co
st o
f spa
re p
art r
epla
cem
ent.
Hel
ps to
und
erst
and
the
aver
age
inve
ntor
y co
st
of re
plac
ing
spar
e pa
rts.
Spar
e Pa
rt C
onsu
mpt
ion
per
Thou
sand
SEK
Out
put
This
is th
e av
erag
e co
st o
f spa
re p
arts
for m
aint
enan
ce w
ork
per
ever
y 10
00 S
EK o
utpu
t. H
elps
to k
now
the
aver
age
cost
of s
pare
par
ts fo
r m
aint
enan
ce fo
r eve
ry th
ousa
nd S
EK sp
ent o
n
14
over
all m
aint
enan
ce.
Spar
e Pa
rt T
urno
ver R
ate
This
is th
e nu
mbe
r of s
pare
par
ts b
ough
t to
repl
ace
faile
d pa
rts
in a
qua
rter
or a
yea
r. H
elps
to u
nder
stan
d sp
are
part
s tur
nove
r rat
e.
Spar
e Pa
rt T
urno
ver P
erio
d Th
is is
the
ratio
of a
vera
ge in
vent
ory
valu
e to
cost
of s
pare
par
ts
with
in th
e ye
ar.
Hel
ps to
und
erst
and
the
spar
e pa
rts t
urno
ver
peri
od.
Slow
Mov
ing
Inve
ntor
y Ra
tio
This
is d
efin
ed a
s the
pro
port
ion
of st
ock
that
has
not
ship
ped
in
a ce
rtai
n am
ount
of t
ime,
e.g
. 90d
ays o
r 180
day
s, an
d in
clud
es
stoc
k w
ith a
low
turn
over
rate
rela
tive
to th
e qu
antit
y on
han
d.
Hel
ps to
und
erst
and
peri
ods o
f no
cons
umpt
ion
of so
me
type
s of s
pare
par
ts fr
om th
e to
tal s
pare
pa
rts i
nven
tory
.
Outsourcing Management
Contractor Statistics
Num
ber o
f Out
sour
ced
Equi
pmen
t Bre
akdo
wns
Th
is is
the
tota
l am
ount
of o
utso
urce
d eq
uipm
ent t
hat i
s out
of
serv
ice.
Hel
ps to
und
erst
and
the
tota
l am
ount
of
equi
pmen
t han
dled
by
outs
ourc
ed m
aint
enan
ce
pers
onne
l tha
t is n
ot w
orki
ng.
Num
ber o
f Out
sour
ced
Mai
nten
ance
Per
sonn
el
This
is th
e to
tal n
umbe
r of o
utso
urce
d m
aint
enan
ce p
erso
nnel
. H
elps
to u
nder
stan
d th
e to
tal n
umbe
r of e
xter
nal
mai
nten
ance
per
sonn
el.
Exte
rnal
Mai
nten
ance
Cos
t Ra
tio
This
is th
e ra
tio o
f cos
t of o
utso
urce
d m
aint
enan
ce p
erso
nnel
to
the
over
all m
aint
enan
ce co
st.
Hel
ps to
und
erst
and
the
cost
of e
xter
nal
mai
nten
ance
per
sonn
el.
Human Resources Management
Skills Management
Tota
l Num
ber o
f Mai
nten
ance
Op
erat
ors
This
is th
e nu
mbe
r of m
aint
enan
ce o
pera
tors
use
d fo
r m
aint
enan
ce ta
sks.
Hel
ps to
und
erst
and
the
tota
l num
ber o
f re
gist
ered
mai
nten
ance
ope
rato
rs a
ssig
ned
to
task
s.
Tota
l Num
ber o
f Mai
nten
ance
En
gine
ers
This
is th
e nu
mbe
r of m
aint
enan
ce e
ngin
eers
use
d fo
r m
aint
enan
ce ta
sks.
Hel
ps to
und
erst
and
the
tota
l num
ber o
f re
gist
ered
mai
nten
ance
eng
inee
rs a
ssig
ned
to
task
s.
Num
ber o
f Mul
ti-Sk
illed
M
aint
enan
ce P
erso
nnel
Th
is is
the
num
ber o
f mul
ti-sk
illed
mai
nten
ance
per
sonn
el u
sed
for m
aint
enan
ce ta
sks.
Hel
ps to
und
erst
and
the
tota
l num
ber o
f re
gist
ered
skill
ed m
aint
enan
ce p
erso
nnel
as
sign
ed to
task
s.
Mai
nten
ance
Ope
rato
r Rat
io
This
is th
e ra
tio o
f mai
nten
ance
ope
rato
rs to
tota
l mai
nten
ance
pe
rson
nel.
Hel
ps to
und
erst
and
the
perc
enta
ge o
f m
aint
enan
ce p
erso
nnel
who
are
ope
rato
rs.
Mai
nten
ance
Eng
inee
r Rat
io
This
is th
e ra
tio o
f mai
nten
ance
eng
inee
rs to
tota
l mai
nten
ance
pe
rson
nel.
Hel
ps to
und
erst
and
the
perc
enta
ge o
f m
aint
enan
ce p
erso
nnel
who
are
eng
inee
rs.
Mul
ti-Sk
illed
Mai
nten
ance
Pe
rson
nel R
atio
Th
is is
the
ratio
of m
ulti-
skill
ed m
aint
enan
ce p
erso
nnel
to to
tal
mai
nten
ance
per
sonn
el.
Hel
ps to
und
erst
and
the
perc
enta
ge o
f m
aint
enan
ce p
erso
nnel
who
are
mul
ti-sk
illed
.
Work Load Management
Aver
age
Num
ber o
f Wor
k Or
ders
Cre
ated
per
Per
son
This
is th
e nu
mbe
r of w
ork
orde
rs cr
eate
d by
eac
h m
aint
enan
ce
wor
ker.
Hel
ps to
und
erst
and
the
aver
age
num
ber o
f wor
k or
ders
crea
ted
by e
ach
mai
nten
ance
wor
ker.
Aver
age
Num
ber o
f Wor
k Or
ders
Exe
cute
d pe
r Per
son
This
is th
e nu
mbe
r of w
ork
orde
rs co
mpl
eted
per
mai
nten
ance
w
orke
r. H
elps
to u
nder
stan
d th
e av
erag
e nu
mbe
r of w
ork
orde
rs co
mpl
eted
by
each
mai
nten
ance
wor
ker.
Aver
age
Daily
Wor
kloa
d pe
r Pe
rson
Th
is is
the
num
ber o
f hou
rs fo
r eac
h m
aint
enan
ce w
orke
r in
a da
y.
Hel
ps to
und
erst
and
the
daily
ave
rage
num
ber o
f w
ork
hour
s for
the
impl
emen
tatio
n of
wor
k or
ders
for e
ach
mai
nten
ance
per
son.
15
Training Management
Aver
age
Annu
al T
rain
ing
Hou
rs p
er M
aint
enan
ce
Oper
ator
This
is th
e ye
arly
mea
n tr
aini
ng h
ours
per
mai
nten
ance
op
erat
or.
Hel
ps to
und
erst
and
the
aver
age
annu
al tr
aini
ng
hour
s for
mai
nten
ance
ope
rato
rs.
Aver
age
Annu
al T
rain
ing
Hou
rs p
er M
aint
enan
ce
Engi
neer
s
This
is th
e ye
arly
mea
n tr
aini
ng h
ours
per
mai
nten
ance
en
gine
er.
Hel
ps to
und
erst
and
the
aver
age
annu
al tr
aini
ng
hour
s for
mai
nten
ance
eng
inee
rs.
Aver
age
Annu
al T
rain
ing
Hou
rs p
er M
ulti-
Skill
ed
Mai
nten
ance
Eng
inee
rs
This
is th
e ye
arly
mea
n tr
aini
ng h
ours
per
mul
ti-sk
illed
m
aint
enan
ce e
ngin
eers
. H
elps
to u
nder
stan
d th
e av
erag
e an
nual
trai
ning
ho
urs f
or m
ulti-
skill
ed m
aint
enan
ce e
ngin
eers
.
Competence Development
Num
ber o
f New
Sen
ior
Mai
nten
ance
Eng
inee
rs
This
is th
e nu
mbe
r of m
aint
enan
ce o
pera
tors
who
hav
e be
com
e m
aint
enan
ce e
ngin
eers
.
Hel
ps to
und
erst
and
the
tota
l num
ber o
f m
aint
enan
ce o
pera
tors
who
hav
e ri
sen
to th
e ra
nk o
f mai
nten
ance
eng
inee
rs.
Ratio
of N
ew S
enio
r M
aint
enan
ce E
ngin
eers
This
is th
e ra
tio o
f the
num
ber o
f mai
nten
ance
ope
rato
rs w
ho
have
bec
ome
mai
nten
ance
eng
inee
rs to
the
tota
l num
ber o
f m
aint
enan
ce e
ngin
eers
.
Hel
ps to
und
erst
and
the
prop
ortio
n of
m
aint
enan
ce o
pera
tors
who
hav
e ri
sen
up to
the
rank
of m
aint
enan
ce e
ngin
eers
N
umbe
r of N
ew M
ulti-
Skill
ed
Mai
nten
ance
Eng
inee
rs
This
is th
e nu
mbe
r of m
aint
enan
ce e
ngin
eers
who
hav
e be
com
e m
ulti-
skill
ed m
aint
enan
ce e
ngin
eers
.
Hel
ps to
und
erst
and
the
tota
l num
ber o
f m
aint
enan
ce e
ngin
eers
who
hav
e ri
sen
to th
e ra
nk o
f mul
ti-sk
illed
mai
nten
ance
eng
inee
rs.
Ratio
of N
ew M
ulti-
Skill
ed
Mai
nten
ance
Eng
inee
rs
This
is th
e ra
tio o
f the
num
ber o
f mai
nten
ance
eng
inee
rs w
ho
have
bec
ome
mul
ti-sk
illed
mai
nten
ance
eng
inee
rs to
the
tota
l nu
mbe
r of m
ulti-
skill
ed m
aint
enan
ce e
ngin
eers
.
Hel
ps to
und
erst
and
the
prop
ortio
n of
m
aint
enan
ce e
ngin
eers
who
hav
e ri
sen
to th
e ra
nk o
f mul
ti-sk
illed
mai
nten
ance
eng
inee
rs.
6. Im
plem
enta
tion
of P
ropo
sed
KPI
s in
a M
inin
g Co
mpa
ny
Besi
des
the
prop
osed
KPI
fram
ewor
k, a
noth
er c
ontr
ibut
ion
in th
is s
tudy
pre
sent
ed in
this
sec
tion
is a
ddre
ssin
g its
impl
emen
tatio
n by
intr
oduc
ing
time
defin
ition
and
gen
eral
form
ula
of e
ach
spec
ified
KPI
. Res
ults
from
this
sec
tion
will
sup
ply
the
guid
ance
of i
mpl
emen
ting
thos
e KP
Is th
roug
h eM
aint
enan
ce. T
he p
roce
dure
, inc
ludi
ng th
e fo
rmul
a us
ed fo
r the
calc
ulat
ion
of K
PI v
alue
s, is
show
n in
Tab
le 4
, Tab
le 5
and
Tab
le 6
.
16
Tabl
e 4:
Impl
emen
tatio
n us
ing
eMai
nten
ance
for A
sset
Ope
ratio
n M
anag
emen
t
Leve
l N
ame
Tim
elin
e Ge
nera
l For
mul
a 3
4
Overall Asset
Shutdown Statistics
Num
ber o
f Sh
utdo
wns
St
op d
ate/
Reg
istr
atio
n da
te β
(que
ry st
art d
ate,
que
ry
term
inat
ion
date
) ππππππ
( ππππππ
ππππππ ππππ
π π πππ π π π π π π π πππππππ π πππ π πππππ π )
Tota
l Shu
tdow
n Ti
me
Regi
stra
tion
date
/ st
op re
cord
dat
e β
(que
ry st
art d
ate,
qu
ery
term
inat
ion
date
) ππππππ
( π π πππ π π π π π π π πππππππ π πππ π ππππ
πππ π ππππ)
Aver
age
Shut
dow
n Ti
me
Regi
stra
tion
date
/ st
op re
cord
dat
e β
(que
ry st
art d
ate,
qu
ery
term
inat
ion
date
) ππππππ
(π π πππ π π π π π π π πππππππ π πππ π ππππ
πππ π ππππ)
πΆπΆπππππΆπΆπ π
(ππππππ
ππππππ ππππ
π π πππ π π π π π π π πππππππ π πππ π πππππ π )
Failure Related
Dow
ntim
e Ra
tio/F
requ
ency
Re
gist
ratio
n da
te /
stop
reco
rd d
ate β
(que
ry st
art d
ate,
qu
ery
term
inat
ion
date
) ππππππ
(ππππππ
ππππππ ππππ
π π πππ π π π π π π π πππππππ π πππ π πππππ π )
ππβππππππ
π π π π β²πππππππππ π
πππ π πΆπΆππβ²
ππππππ
(ππππππ
ππππππ ππππ
π π πππ π π π π π π π πππππππ π πππ π πππππ π )
Dow
ntim
e Ra
tio/T
ime
Regi
stra
tion
date
/ st
op re
cord
dat
e β
(que
ry st
art d
ate,
qu
ery
term
inat
ion
date
) ππππππ
(π π πππ π π π π π π π πππππππ π πππ π ππππ
πππ π ππππ)
ππβππππππ
π π π π β²πππππππππ π
πππ π πΆπΆππβ²
ππππππ
(π π πππ π π π π π π π πππππππ π πππ π ππππ
πππ π ππππ)
Failu
re M
ode
Repo
rtin
g Ra
te
Wor
k or
der r
egis
trat
ion
/cre
atio
n da
te β
(que
ry st
art
date
, que
ry te
rmin
atio
n da
te) I
tem
: Wor
k or
der t
ype;
Sy
stem
/sec
tion;
Wor
k fo
r sup
plie
r gro
up; W
ork
supp
lier
attr
ibut
e
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
ππππππππ πππππ π πππππ π )
ππβππππππ
π π π π β²πππππππππππππ π π π ππππβ² πππΆπΆπ π
πππππ π ππππππππ
πππππ π ππ π π π π
πΆπΆπππ π
ππππππππ
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
ππππππππ πππππ π πππππ π )
ππβππππππ
π π π π β²πππππππππππππ π π π ππππβ²
Reas
on fo
r Fa
ilure
Re
gist
ratio
n Ra
te
wor
k or
der r
egis
trat
ion
date
β (q
uery
star
t dat
e, q
uery
te
rmin
atio
n da
te)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
ππππππππ πππππ π πππππ π )
ππβππππππ
π π π π β²πππππππππππππ π π π ππππβ²
πππΆπΆπ π
πππππ π ππππππππ
πππππππ π πππΆπΆ π π π π
πΆπΆπππ π
ππππππππ
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
ππππππππ πππππ π πππππ π )
ππβππππππ
π π π π β²πππππππππππππ π π π ππππβ²
Availability
Operational Availability
Avai
labi
lity
Regi
stra
tion
date
/ st
op re
cord
dat
e β
(que
ry st
art d
ate,
qu
ery
term
inat
ion
date
) πππππ π ππππ ππ
πππππππππ π π π πΆπΆπ π
πππ π ππππ
(πππππ π ππππ
πππππππππππ π π π πΆπΆπ π
πππ π ππππ
+ π·π·πππ·π·
πΆπΆ π π π π ππππ π·π·ππππ
π π ππ πππππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
)
Reliability
Mean Reliability Measures
Mea
n Ti
me
Betw
een
Failu
re
Regi
stra
tion
date
/ st
op re
cord
dat
e β
(que
ry st
art d
ate,
qu
ery
term
inat
ion
date
) ππππππ
( πππππππππππ π π π πΆπΆπ π
πππ π ππππ)ππβππππππ
π π π π ππππ
π π π π πππππππππππ π ππππππππ
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΉπΉπππ π πππππππππ π )
Mea
n Ti
me
To
Failu
re
Regi
stra
tion
date
/ st
op re
cord
dat
e β
(que
ry st
art d
ate,
qu
ery
term
inat
ion
date
) ππππππ
( πππππππππππ π π π πΆπΆπ π
πππ π ππππ)ππβππππππ
π π π π ππππ
π π π π πΆπΆπππ π
πππππππππππ π ππππππππ
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΉπΉπππ π πππππππππ π )
Mea
n Up
Tim
e Re
gist
ratio
n da
te /
star
t rec
ord
date
β (q
uery
star
t dat
e,
quer
y te
rmin
atio
n da
te)
ππππππ
(πππππ π π π ππππ π π πΆπΆ
π»π»πππππππ π
) ππππππ
ππππππ ππππ
πππππ π π π ππππ πΈπΈπππππΆπΆπ π π π
17
Failure Related
Emer
genc
y Fa
ilure
Rat
io
Wor
k or
der r
egis
trat
ion/
crea
tion
date
β (q
uery
star
t da
te, q
uery
end
dat
e)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
ππππππππ πππππ π πππππ π )
ππβππππππ
π π π π β²πππππππππ π πππΆπΆππππ πππππππππ π ππ
π·π·ππππππ πππππ π ππππβ²
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
ππππππππ πππππ π πππππ π )
Emer
genc
y Fa
iled
Equi
pmen
t Rat
io
Wor
k or
der r
egis
trat
ion/
crea
tion
date
β (q
uery
star
t da
te, q
uery
end
dat
e)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπΈπΈπππ π πππππππΆπΆπ π )
ππβππππππ
π π π π β²πππππππππ π πππΆπΆππππ πππππππππ π ππ
π·π·ππππππ πππππ π ππππβ²
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
ππππππππ πππππ π πππππ π )
Corr
ectiv
e M
aint
enan
ce
Failu
re R
ate
Wor
k or
der r
egis
trat
ion/
crea
tion
date
β (q
uery
star
t da
te, q
uery
end
dat
e)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
ππππππππ πππππ π πππππ π ππβππππππ
π π π π β²πππππππππππππ π π π ππππβ²
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
ππππππππ πππππ π πππππ π )
Repe
at F
ailu
re
Wor
k or
der r
egis
trat
ion/
crea
tion
date
β (q
uery
star
t da
te, q
uery
end
dat
e)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
ππππππππ πππππ π πππππ π )
ππβππππππ
πππππ π ππππππππ
πππππ π ππ
> 1
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
ππππππππ πππππ π πππππ π )
ππβππππππ
π π π π β²πππππππππππππ π π π ππππβ²
Maintainability
Mean Maintainability Measures
Mea
n D
ownt
ime
Regi
stra
tion
date
/ st
op re
cord
dat
e β
(que
ry st
art d
ate,
qu
ery
term
inat
ion
date
) ππππππ
(π·π·πππ·π·
πΆπΆπ π π π ππππ π π πΆπΆ
π»π»πππππππ π
)ππππππ
ππππππ ππππ
π·π·πππ·π·
πΆπΆπ π π π ππππ πΈπΈπππππΆπΆπ π π π
Mea
n Ti
me
Betw
een
Mai
nten
ance
Regi
stra
tion
date
/ st
art r
ecor
d da
te β
(que
ry st
art d
ate,
qu
ery
term
inat
ion
date
) ππππππ
(πππππ π π π ππππ)
ππππππ
ππππππ ππππ
πππππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
π΄π΄πππ π π π πππΆπΆπ π
Mea
n Ti
me
To
Mai
ntai
n Re
gist
ratio
n da
te /
stop
reco
rd d
ate β
(que
ry st
art d
ate,
qu
ery
term
inat
ion
date
) ππππππ
(βπΆπΆβ
πΌπΌπΆπΆπ π π π πππ π π π ππππππ
πππΆπΆπ π π π πππ π πππππ π
π π ππ πππππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
) πΆπΆπππππΆπΆπ π (
βπΆπΆβ ππ
πΆπΆπ π π π π π
)
Mea
n Ti
me
To
Repa
ir
Regi
stra
tion
date
/ st
op re
cord
dat
e β
(que
ry st
art d
ate,
qu
ery
term
inat
ion
date
)
ππππππ
(βπΆπΆβ
πΌπΌπΆπΆπ π π π πππ π π π ππππππ
πππΆπΆπ π π π πππ π πππππ π
π π ππ π π πππ π π π ππππππ
)πΆπΆπππππΆπΆπ π (
βπΆπΆβ ππ
πΆπΆπ π π π π π
)
Fals
e Al
arm
Rat
e Re
gist
ratio
n da
te β
(que
ry st
art d
ate,
que
ry te
rmin
atio
n da
te)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΉπΉπππππ π ππ
π΄π΄ππππππππ
π π )πππππ π ππππ ππ
ππππππππππ ππππ
π΄π΄ππππππππ
π π
Safety
Occupational Safety
Num
ber o
f Saf
ety
Inci
dent
s Re
gist
ratio
n da
te β
(que
ry st
art d
ate,
que
ry te
rmin
atio
n da
te)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πππππππππ π ππ πΌπΌπΆπΆπππ π π π πππΆπΆπ π π π )
Inju
ry R
ate
Regi
stra
tion
date
β (q
uery
star
t dat
e, q
uery
term
inat
ion
date
) πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πππππππππ π ππ πΌπΌπΆπΆπππ π π π πππΆπΆπ π π π )
ππβππππππ
πΌπΌπΆπΆπΌπΌππππππ
πππππ π π·π·πππππΆπΆ
β²π π πππ π ππ 1β²
πππΆπΆπ π
β²π π πππ π ππ 2β²
ππππππ
(πππππππππ π πΆπΆπ π
π»π»πππππππ π
)
Inju
ry R
ate
per
Failu
re
Regi
stra
tion
date
β (q
uery
star
t dat
e, q
uery
term
inat
ion
date
) πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΉπΉπππ π πππππππππ π πΆπΆπππππ π π π πΆπΆπ π πΌπΌπΆπΆπΌπΌππππππ
)πππππ π ππππ ππ
ππππππππππ ππππ
πΉπΉπππ π πππππππππ π
β10
0
18
Tabl
e 5:
Impl
emen
tatio
n us
ing
eMai
nten
ance
for M
aint
enan
ce P
roce
ss M
anag
emen
t
Le
vel
Nam
e Ti
mel
ine
Gene
ral F
orm
ula
3 4
MaintenanceManagement
Maintenance Strategy
Criti
cal E
quip
men
t Rat
io
Re
gist
ratio
n da
te β
(que
ry st
art d
ate,
qu
ery
term
inat
ion
date
) πΆπΆπππππΆπΆπ π (πΆπΆππππππππππ ππππ
πΈπΈπΈπΈπππ π πππππππΆπΆπ π )
ππβππππππ
π π π π β²πΆπΆπππ π π π π π ππππππβ²
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπΈπΈπππ π πππππππΆπΆπ π )
Prev
entiv
e M
aint
enan
ce
Rate
W
ork
orde
r reg
istr
atio
n da
te β
(que
ry
star
t dat
e, q
uery
term
inat
ion
date
) πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπΈπΈπππ π πππππππΆπΆπ π )
ππβππππππ
π π π π β²πππππ π ππππππ
π·π·ππππππ πππππ π ππππβ²
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπΈπΈπππ π πππππππΆπΆπ π )
Pred
ictiv
e M
aint
enan
ce
Rate
(PdM
)
Regi
stra
tion
date
β (q
uery
star
t dat
e,
quer
y te
rmin
atio
n da
te)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπΈπΈπππ π πππππππΆπΆπ π )
ππβππππππ
π π π π β²π π π π πππ π πππ π πππππΆπΆπ π π π πππππ π πΆπΆπ π πππππ π πΆπΆπ π β²
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπΈπΈπππ π πππππππΆπΆπ π )
Prev
entiv
e M
aint
enan
ce
Rate
(Cri
tical
Equ
ipm
ent)
W
ork
orde
r reg
istr
atio
n da
te β
(que
ry
star
t dat
e, q
uery
term
inat
ion
date
) πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπΈπΈπππ π πππππππΆπΆπ π )ππβππππππ
π π π π β²πππππ π ππππππ
π·π·ππππππ πππππ π ππππβ²
& β²πππππ π π π π π ππππππβ²
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπΈπΈπππ π πππππππΆπΆπ π )ππβππππππ
π π π π β²πΆπΆπππ π π π π π ππππππβ²
Pred
ictiv
e M
aint
enan
ce
Rate
(Cri
tical
Equ
ipm
ent)
Re
gist
ratio
n da
te β
(que
ry st
art d
ate,
qu
ery
term
inat
ion
date
)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπΈπΈπππ π πππππππΆπΆπ π )
ππβππππππ
π π π π β²πππππ π π π π π ππππππβ² π π π π
β²π π π π πππ π πππ π πππππΆπΆπ π π π πππππ π πΆπΆπ π πππππ π πΆπΆπ π β²
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπΈπΈπππ π πππππππΆπΆπ π )ππβππππππ
π π π π β²πππππ π π π π π ππππππβ²
Run
to F
ailu
re (R
TF) R
atio
fo
r Cri
tical
Equ
ipm
ent
Regi
stra
tion
date
β (q
uery
star
t dat
e,
quer
y te
rmin
atio
n da
te)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπΈπΈπππ π πππππππΆπΆπ π )
ππβππππππ
πΆπΆβ²πππ π π π π π ππππππβ² π π π π
πΆπΆππ β² π π π π πππ π πππ π πππππΆπΆπ π π π πππππ π πΆπΆπ π πππππ π πΆπΆπ π β²
πΆπΆππ ππππ
π·π·ππππππ πππππ π ππππ
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπΈπΈπππ π πππππππΆπΆπ π )
ππβππππππ
π π π π β²πππππ π π π π π ππππππβ²
Plan
ned
Mai
nten
ance
vs
Unpl
anne
d M
aint
enan
ce
Wor
k or
der r
egis
trat
ion
date
β (q
uery
st
art d
ate,
que
ry te
rmin
atio
n da
te)
ππππππ
(ππππππππ πππππ π πππππ π )
ππβππππππ
ππππ
_ππππππππ
=β²πππππππΆπΆβ²
ππππππ
(ππππππππ πππππ π πππππ π )
ππβππππππ
ππππ
_ππππππππ
= β²πππΆπΆπππππππΆπΆπππ π β²
Maintenance Planning
Quantity Related
Num
ber o
f Pla
nned
Wor
k Or
ders
Cre
ated
Wor
k or
der c
reat
ion
date
β (q
uery
star
t da
te, q
uery
end
dat
e)
ππππππ
( ππππππππ πππππ π πππππ π )
ππβππππππ
ππππ
_ππππππππ
= β²πππππππΆπΆβ²
Time Related
Aver
age
Plan
ned
Exec
utio
n Ti
me
Wor
k or
der c
reat
ion
date
β (q
uery
star
t da
te, q
uery
end
dat
e)
ππππππ
(πΈπΈπΈπΈπππππππ π π π πππΆπΆ
πππ π ππππ)
ππβππππππ
ππππ
_ππππππππ
= β²πππππππΆπΆβ²
ππππππ
( ππππππππ πππππ π πππππ π )
ππβππππππ
ππππ
_ππππππππ
= β²πππππππΆπΆβ²
Resource Related
Tota
l Num
ber o
f Pla
nned
In
tern
al L
abou
r Hou
rs
Wor
k or
der c
reat
ion
date
β (q
uery
star
t da
te, q
uery
end
dat
e)
ππππππ
(ππππππππππππ π»π»πππππππ π
) ππβππππππ
π·π·ππππππ πππππ π πππ π ππππππ
= ββπΌπΌπΆπΆπ π πππππΆπΆππππβ
& ππ
ππ_ππππππππ
= β²πππππππΆπΆβ²
Aver
age
Plan
ned
Inte
rnal
La
bour
Hou
rs
Wor
k or
der c
reat
ion
date
β (q
uery
star
t da
te, q
uery
end
dat
e)
ππππππ
(ππππππππππππ π»π»πππππππ π
) ππβππππππ
π·π·ππππππ πππππ π πππ π ππππππ
= βπΌπΌπΆπΆπ π πππππΆπΆππππβ
& ππππ
_ππππππππ
= β²πππππππΆπΆβ²
πΆπΆπππππΆπΆπ π (ππππππππ πππππ π πππππ π )
ππβππππππ
ππππ
_ππππππππ
= β²πππππππΆπΆβ²
Tota
l Num
ber o
f Pla
nned
W
ork
orde
r cre
atio
n da
te β
(que
ry st
art
ππππππ
(ππππππππππππ π»π»πππππππ π
) ππβππππππ
π·π·ππππππ πππππ π πππ π ππππππ
= βπΈπΈπΈπΈπ π πππππΆπΆππππβ²
& ππ
ππ_ππππππππ
= β²πππππππΆπΆβ²
19
Exte
rnal
Lab
our H
ours
da
te, q
uery
end
dat
e)
Aver
age
Plan
ned
Exte
rnal
La
bour
Hou
rs
Wor
k or
der c
reat
ion
date
β (q
uery
star
t da
te, q
uery
end
dat
e)
ππππππ
(ππππππππππππ π»π»πππππππ π
) ππβππππππ
π·π·ππππππ πππππ π πππ π ππππππ
= βπΈπΈπΈπΈπ π πππππΆπΆππππβ
& ππππ
_ππππππππ
= β²πππππππΆπΆβ²
)πΆπΆπππππΆπΆπ π (
ππππππππ πππππ π πππππ π )
ππβππππππ
ππππ
_ππππππππ
= β²πππππππΆπΆβ²
Plan
ned
Num
ber o
f Mat
eria
l Us
ed
Wor
k or
der c
reat
ion
date
β (q
uery
star
t da
te, q
uery
end
dat
e)
ππππππ
(ππππππππππ
ππππππ
ππππππ)
ππβππππππ
ππππ
_ππππππππ
= β²πππππππΆπΆβ²
Aver
age
Plan
ned
Num
ber o
f M
ater
ials
Use
d W
ork
orde
r cre
atio
n da
te β
(que
ry st
art
date
, que
ry e
nd d
ate)
ππππππ
(ππππππππππ
ππππππ
ππππππ)
ππβππππππ
ππππ
_ππππππππ
= β²πππππππΆπΆβ²
πΆπΆπππππΆπΆπ π (ππππππππ πππππ π πππππ π )
ππβππππππ
ππππ
_ππππππππ
= β²πππππππΆπΆβ²
Cost Related
Tota
l Cos
t of P
lann
ed
Hum
an R
esou
rces
W
ork
orde
r cre
atio
n da
te β
(que
ry st
art
date
, que
ry e
nd d
ate)
ππππππ
( ππππππππππππ π π πππ π ππ
) β( πππππππΆπΆπΆπΆπππ π
ππππππππππππ ππππππ
ππππππ)ππβππππππ
ππππππππππππ
=
β²πππππππΆπΆβ²
& π·π·ππππππ πππππ π πππ π ππππππ
= β²πππΈπΈπ π πππππΆπΆππππβ²
Aver
age
Plan
ned
Exte
rnal
H
uman
Res
ourc
e Co
sts
Wor
k or
der c
reat
ion
date
β (q
uery
star
t da
te, q
uery
end
dat
e)
ππππππ
( ππππππππππππ π π πππ π ππ
) β (πππππππΆπΆ
ππππππππππππ πππ π ππππ)ππβππππππ
ππππππππππππ
= β²πππππππΆπΆβ²
π·π·ππππππ πππππ π πππ π ππππππ
= β²πππΈπΈπ π πππππΆπΆππππβ²
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
ππππππππ πππππ π πππππ π )ππβππππππ
ππππππππππππ
=β²πππππππΆπΆβ²
π·π·ππππππ πππππ π πππ π ππππππ
=β²πππΈπΈπ π πππππΆπΆππππβ²
Tota
l Cos
t of P
lann
ed
Mat
eria
ls
Wor
k or
der c
reat
ion
date
β (q
uery
star
t da
te, q
uery
end
dat
e)
ππππππ
(ππππππππππ
πππππππ π π π
πππππππΆπΆπ π π π π π ππ)
β (ππππππππππ πππππππ π π π πππππ π ππππ)
ππβππππππ
ππππ
_ππππππππ
= β²πππππππΆπΆβ²
Plan
ned
Aver
age
Mat
eria
l Co
st
Wor
k or
der c
reat
ion
date
β (q
uery
star
t da
te, q
uery
end
dat
e)
ππππππ
(ππππππ
ππππππ ππππ
ππππππππππ
πππππππ π π π
) β
(ππππππππππ
πππππ π ππππ
) ππβππππππ
ππππ
_ππππππππ
= β²πππππππΆπΆβ²
ππππππ
(ππππππ
ππππππ ππππ
ππππππππ πππππ π πππππ π )
ππβππππππ
ππππ
_ππππππππ
= β²πππππππΆπΆβ²
Labo
ur C
ost R
atio
W
ork
orde
r cre
atio
n da
te β
(que
ry st
art
date
, que
ry e
nd d
ate)
πππππ π ππππ πΆπΆπππ π π π ππππ πππππππΆπΆπΆπΆπππ π π»π»ππππ
πππΆπΆ π π πππ π πππππππππππ π
(πππππ π ππππ
πΆπΆπππ π π π ππππ πππππππΆπΆπΆπΆπππ π π»π»ππππ
πππΆπΆ π π πππ π πππππππππππ π
+ πππππ π ππππ
πΆπΆπππ π π π ππππ πππππππΆπΆπΆπΆπππ π πππππ π πππππ π πππππ π
)
Plan
ned
Mat
eria
l Cos
t Rat
io
Wor
k or
der c
reat
ion
date
β (q
uery
star
t da
te, q
uery
end
dat
e)
πππππ π ππππ
πΆπΆπππ π π π ππππ πππππππΆπΆπΆπΆπππ π πππππ π πππππ π πππππ π
( πππππ π ππππ
πΆπΆπππ π π π ππππ πππππππΆπΆπΆπΆπππ π π»π»ππππ
πππΆπΆ π π πππ π πππππππππππ π
+ πππππ π ππππ
πΆπΆπππ π π π ππππ πππππππΆπΆπΆπΆπππ π πππππ π πππππ π πππππ π
)
Maintenance Preparation
Work Order Creation
Plan
ned
Star
t / E
nd T
ime
Regi
stra
tion
Rate
W
ork
orde
r reg
istr
atio
n/cr
eatio
n da
te β
(q
uery
star
t dat
e, q
uery
end
dat
e)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
+ (πΆπΆπππππππππΆπΆπ π
ππππππππ πππππ π πππππ π )
ππβππππππ
βπππππππΆπΆπΆπΆπππ π
π π π π πππππ π
/πππΆπΆπ π
π π π π ππππβ
π π π π πππππ π π π πππ π
πΆπΆπππππΆπΆπ π
(ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
+ (πΆπΆπππππππππΆπΆπ π ππ
ππππππ πππππ π πππππ π )
Plan
ned
Spar
e Pa
rts
Regi
stra
tion
Rate
W
ork
orde
r reg
istr
atio
n /
crea
tion
date
β
(que
ry st
art d
ate,
que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
+
(ππππππ
ππππππ ππππ
πΆπΆπππππππππΆπΆπ π
ππππππππ πππππ π πππππ π )
ππβππππππ
β²π π ππππππππ
πππππππ π π π
πππππππΆπΆβ²
π π π π πππππ π π π πππ π
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
+ (πΆπΆπππππππππΆπΆπ π ππ
ππππππ πππππ π πππππ π )
Plan
ned
Man
-Hou
r Re
gist
ratio
n Ra
te
Wor
k or
der r
egis
trat
ion/
crea
tion
date
β
(que
ry st
art d
ate,
que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
+ (ππ
ππππππππππ ππππ
πΆπΆπππππππππΆπΆπ π
ππππππππ πππππ π πππππ π )
ππβππππππ
βπππππππΆπΆπΆπΆπππ π
ππππππππππππ
βπππππππ π
β π π π π πππππ π π π πππ π
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
+ (ππππππ
ππππππ ππππ
πΆπΆπππππππππΆπΆπ π
ππππππππ πππππ π πππππ π )
Plan
ned
Dow
ntim
e Re
gist
ratio
n Ra
te
Wor
k or
der r
egis
trat
ion/
crea
tion
date
β
(que
ry st
art d
ate,
que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
+
(πΆπΆπππππππππΆπΆπ π
ππππππππ πππππ π ππππ
) ππβππππππ
βπππππππΆπΆπΆπΆπππ π
ππππππππππππ
π π π π ππππβ
π π π π πππππ π π π πππ π
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
+ (πΆπΆπππππππππΆπΆπ π ππ
ππππππ πππππ π ππππ
ππππππ
ππππππ)
Stan
dard
Ope
ratin
g Pl
an
Regi
stra
tion
Rate
W
ork
orde
r reg
istr
atio
n/cr
eatio
n da
te β
(q
uery
star
t dat
e, q
uery
end
dat
e)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
+ (πΆπΆπππππππππΆπΆπ π
ππππππππ πππππ π πππππ π )
ππβππππππ
βπ π π π πππΆπΆπ π πππππ π π·π·ππππππ πππππππΆπΆ
β π π π π π π π π πππππΆπΆ
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
+ (πΆπΆπππππππππΆπΆπ π ππ
ππππππ πππππ π πππππ π )
20
Plan
ned
Wor
k Ty
pe
Regi
stra
tion
Rate
W
ork
orde
r reg
istr
atio
n/cr
eatio
n da
te β
(q
uery
star
t dat
e, q
uery
end
dat
e)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
+ ( ππ
ππππππππππ ππππ
πΆπΆπππππππππΆπΆπ π
ππππππππ πππππ π πππππ π )ππβππππππ
βπ·π·ππππππ πππππ π πππ π ππππππ
πππππππΆπΆβ²
π π π π πππππ π π π πππ π
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
+ (πΆπΆπππππππππΆπΆπ π ππ
ππππππ πππππ π πππππ π )
Job
Prio
rity
Reg
istr
atio
n Ra
te
Wor
k or
der r
egis
trat
ion/
crea
tion
date
β
(que
ry st
art d
ate,
que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
+
(πΆπΆπππππππππΆπΆπ π
ππππππππ πππππ π ππππ
ππππππ
ππππππ)
ππβππππππ
β²πΌπΌππππ
πππππ π πππππ π π π ππβ²
π π π π π π π π πππππΆπΆ
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
+ (πΆπΆπππππππππΆπΆπ π ππ
ππππππ πππππ π ππππ
)
Work Order Feedback
Actu
al S
pare
Par
ts U
se
Regi
stra
tion
Rate
W
ork
orde
r reg
istr
atio
n β
(que
ry st
art
date
, que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
ππβππππππ
β²ππππππππ πππ π ππ
ππππ π π ππππππππ πππππππ π π π β²
π π π π πππππ π π π πππ π
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
πππππ π πππππ π )
ππβππππππ
β²ππππππππππ
πππππππ π π π
πππππππΆπΆβ²
π π π π πππππ π π π πππ π
Actu
al M
an-H
our
Regi
stra
tion
Rate
W
ork
orde
r reg
istr
atio
n β
(que
ry st
art
date
, que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
πππππ π πππππ π )
ππβππππππ
βπ·π·βπππΆπΆ πππ π π π πΆπΆπ π πππππΆπΆππππππβ π π π π
πππππ π π π πππ π
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
πππππ π πππππ π )
Actu
al D
ownt
ime
Regi
stra
tion
Rate
W
ork
orde
r reg
istr
atio
n β
(que
ry st
art
date
, que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
πππππ π πππππ π )
ππβππππππ
βπππππ π ππππππ π π πππ·π·
πΆπΆπ π π π ππππβ
π π π π πππππ π π π πππ π
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
πππππ π πππππ π )
ππβππππππ
βπππππππΆπΆπΆπΆπππ π
π π πππ·π·
πΆπΆπ π π π ππππβ
π π π π πππππ π π π πππ π
Wor
k Or
der R
egis
trat
ion
Back
-Log
W
ork
orde
r reg
istr
atio
n β
(que
ry st
art
date
, que
ry e
nd d
ate)
( ππ
ππππππ πππππ π ππππ
π π πππ π π π π π π π πππππ π π π πππΆπΆ πΆπΆπππππππππππ π π π πππΆπΆ π·π·πππ π ππ πππΆπΆπ π πππ π ππππ)
β (π΄π΄
πππ π ππππππ π·π·
πππ π ππ πππΆπΆπ π πππ π ππππ)
Work Order Approval
Tota
l Num
ber o
f Wor
k Or
ders
W
ork
orde
r cre
atio
n da
te β
(que
ry st
art
date
, que
ry e
nd d
ate)
ππππππ
(ππππππππ πππππ π πππππ π )
π·π·βππππππ
(ππππ
_ππππππππ
= β²πΆπΆπππππ π π π ππ
πππππππππππ π β²)
Tota
l Num
ber o
f App
rove
d W
ork
Orde
rs
Wor
k or
der c
reat
ion
date
β (q
uery
star
t da
te, q
uery
end
dat
e)
ππππππ
( ππππππππ πππππ π πππππ π )π·π·βππππππ
ππππππππππππ
=
β²πΆπΆπππππ π π π ππ
πππππππππππ π β²
& β²πππππ π
πΆπΆππ πππππΌπΌπππππ π π π πππΆπΆ πππππππππππ π β²
Tota
l Num
ber o
f Un
appr
oved
Wor
k Or
ders
W
ork
orde
r cre
atio
n da
te β
(que
ry st
art
date
, que
ry e
nd d
ate)
ππππππ
( ππππππππ πππππ π πππππ π )π·π·βππππππ
ππππππππππππ
=
β²πΆπΆπππππ π π π ππ
πππππππππππ π β²
& β²πππππ π
πππππΌπΌπππππ π π π πππΆπΆ
πππππππππππ π β²
Wor
k Or
der A
ppro
val R
atio
W
ork
orde
r cre
atio
n da
te β
(que
ry st
art
date
, que
ry e
nd d
ate)
ππππππππ πππππ π πππππ π π π ππ
ππππ π΄π΄πππππππππππππ π
ππππππ
ππππππ ππππ
πππππππΆπΆπΆπΆπππ π
ππππππππ πππππ π πππππ π πΆπΆπππππππ π πππ π
One-
time
Appr
oved
Wor
k Or
der R
atio
Wor
k or
der c
reat
ion
date
β (q
uery
star
t da
te, q
uery
end
dat
e)
πππππ π ππππ ππ
ππππππππππ ππππ
π΄π΄πππππππππππππ π ππππππππ πππππ π πππππ π
πππππ π ππππ ππ
ππππππππππ ππππ
ππππππππ πππππ π πππππ π
Aver
age
time
lag
for
Repo
rtin
g an
d Ap
prov
ing
Wor
k Or
ders
Wor
k or
der c
reat
ion
date
β (q
uery
star
t da
te, q
uery
end
dat
e)
ππππππ
( ππππππππ πππππ π ππππ
π΄π΄ππππππππππππππ π·π·
πππ π ππ)
β (ππ
ππππππ πππππ π ππππ
π π πππππππππ π π·π·
πππ π ππ)
π·π·βππππππ
ππππ
_ππππππππ
= β²π π πππππππππ π π π
πππΈπΈπππ π πππππ π
πππππ π ππππ ππ
ππππππππππ ππππ
π΄π΄πππππππππππππ π ππππππππ πππππ π πππππ π
21
Maintenance Execution
Quantity Related
Num
ber o
f Pla
nned
Wor
k Or
ders
Com
plet
ed
Wor
k or
der c
ompl
etio
n da
te β
(que
ry
star
t dat
e, q
uery
end
dat
e)
πΆπΆπππππΆπΆπ π (π π πππ π π π π π π π πππππππ π
ππππππππ πππππ π ππππ
) ππβππππππ
β²ππππ
_ππππππππ π π π π
βπππππππΆπΆβ²
Num
ber o
f Unp
lann
ed W
ork
Orde
rs C
ompl
eted
W
ork
orde
r com
plet
ion
date
β (q
uery
st
art d
ate,
que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (π π πππ π π π π π π π πππππππ π
ππππππππ πππππ π ππππ
) ππβππππππ
ππππ
_ππππππππ π π π π
βπππΆπΆπππππππΆπΆπΆπΆπππ π
β
Num
ber o
f Wor
k Or
ders
Co
mpl
eted
per
Shi
ft W
ork
orde
r com
plet
ion
date
β (q
uery
st
art d
ate,
que
ry e
nd d
ate)
οΏ½ππππππ
ππππππ ππππ
ππππππππ πππππ π πππππ π πππππππππππππππππ π
πππ π ππππβπππ π πππππππ π
πππππ π ππππ ππ
ππππππππππ ππππ
ππππβπππ π πππππππ π
ππππππππ πππππ π πππππ π
οΏ½β
100
Wor
k Or
der R
esol
utio
n Ra
te
Wor
k or
der c
ompl
etio
n da
te β
(que
ry
star
t dat
e, q
uery
end
dat
e)
οΏ½ππππππ
ππππππ ππππ
ππππππππ πππππ π πππππ π πππππππππππππππππ π
πππ π ππππβπππ π πππππππ π
πππππ π ππππ ππ
ππππππππππ ππππ
ππππβπππ π πππππππ π
ππππππππ πππππ π πππππ π
οΏ½β
100
Time Related
Aver
age
Wor
k Or
der T
ime
Wor
k or
der c
ompl
etio
n da
te β
(que
ry
star
t dat
e, q
uery
end
dat
e)
ππππππ
(πΆπΆππππ
πππππππ π πππ π
πππππΆπΆ
βπππ π ππππ
ππππππππ πππππ π ππππ
πΈπΈπΈπΈπππππππ π π π πππΆπΆ
πππ π ππππ)
πΆπΆπππππΆπΆπ π (πΆπΆπππππππππππ π πππ π
πππππΆπΆ
βπππ π ππππ
ππππππππ πππππ π ππππ
)
Aver
age
Wai
ting
Tim
e fo
r Pe
rson
nel
Wor
k or
der c
ompl
etio
n da
te β
(que
ry
star
t dat
e, q
uery
end
dat
e)
ππππππ
(πΆπΆππππ
πππππππ π πππ π
πππππΆπΆ
βπππ π ππππ
ππππππππ πππππ π ππππ
π·π·π π π π β πππ π ππππππ π π πΆπΆ
ππππππππππ
πππ π ππππ)
πΆπΆπππππΆπΆπ π (πΆπΆπππππππππππ π πππ π
πππππΆπΆ
βπππ π ππππ
ππππππππ πππππ π ππππ
)
Aver
age
Wai
ting
Tim
e fo
r Sp
are
Part
s W
ork
orde
r com
plet
ion
date
β (q
uery
st
art d
ate,
que
ry e
nd d
ate)
ππππππ
( ππππππππππ
π π πΆπΆ ππππππππππ
πππ π ππππ
] ππβππππππ
πΆπΆππππ
πππππππ π πππ π
πππππΆπΆ
βπππ π ππππ
ππππππππ πππππ π ππππ
ππππππππππ
πππππππ π π π
πππππππΆπΆ ππππππππ πππππ π ππππ
πΆπΆπππππΆπΆπ π (πΆπΆπππππππππππ π πππ π
πππππΆπΆ
βπππ π ππππ
ππππππππ πππππ π ππππ
& ππππππππππ
πππππππ π π π
πππππππΆπΆ ππππππππ πππππ π ππππ
)
Pers
onne
l Wai
ting
Tim
e Ra
tio
Wor
k or
der c
ompl
etio
n da
te β
(que
ry
star
t dat
e, q
uery
end
dat
e)
π΄π΄πππππππππ π ππ πππππ π π π π π πΆπΆπ π
πππ π ππππ ππππππ πππππππ π πππΆπΆπΆπΆππππ
π΄π΄πππππππππ π ππ
ππππππππ πππππ π ππππ
πππ π ππππ
Spar
e Pa
rts W
aitin
g Ti
me
Ratio
W
ork
orde
r com
plet
ion
date
β (q
uery
st
art d
ate,
que
ry e
nd d
ate)
π΄π΄πππππππππ π ππ πππππ π π π π π πΆπΆπ π
πππ π ππππ ππππππ ππππππππππ πππππππ π π π
π΄π΄πππππππππ π ππ ππππππππ πππππ π ππππ
πππ π ππππ
Aver
age
Mai
nten
ance
Ou
tage
Tim
e W
ork
orde
r com
plet
ion
date
β (q
uery
st
art d
ate,
que
ry e
nd d
ate)
ππππππ
( πΈπΈπΈπΈπππππππ π π π πππΆπΆ
πππ π ππππ)ππβππππππ
πππΈπΈπ π π π π π
ππππππ
πππππππ π πππ π
πππππππ π
βπ π π π ππππ
ππππ πππππ π πΆπΆ π·π·ππππππ πππππ π ππππ
πΆπΆπππππΆπΆπ π (πΆπΆπππππππππππ π πππ π
πππ π πππππ π βπππ π ππππ
ππππ πππππ π πΆπΆ ππππππππ πππππ π ππππ
)
Aver
age
Wai
ting
Tim
e of
Pe
rson
nel d
urin
g Sh
utdo
wn
Wor
k or
der c
ompl
etio
n da
te β
(que
ry
star
t dat
e, q
uery
end
dat
e)
ππππππ
( πππ π ππππππ
π π πΆπΆ ππππππππππ
πππ π ππππ)ππβππππππ
πππΈπΈπ π π π π π
ππππππ
πππππππ π πππ π
π π π π πππππ π
ππππ πππππ π πΆπΆ π·π·ππππππ πππππ π ππππ
πΆπΆπππππΆπΆπ π (πΆπΆπππππππππππ π πππ π
πππ π πππππ π
ππππ πππππ π πΆπΆ ππππππππ πππππ π ππππ
)
Aver
age
Wai
ting
Tim
e fo
r Sp
are
Part
s dur
ing
Shut
dow
n
Wor
k or
der c
ompl
etio
n da
te β
(que
ry
star
t dat
e, q
uery
end
dat
e)
ππππππ
( ππππππππππ
π π πΆπΆ ππππππππππ
πππ π ππππ)ππβππππππ
ππππππ
πππππππ π πππ π
π π π π ππππ πππ π πΆπΆππ
π·π·π π π π β π π ππππππππ πππππππ π π π πππππππΆπΆ
π·π·ππππππ πππππ π ππππ
πΆπΆπππππΆπΆπ π (πΆπΆπππππππππππ π πππ π
πππ π ππππ πππ π πΆπΆππ
& πππ π π π β ππππππππππ πππππππ π π π πππππππΆπΆ
ππππππππ πππππ π ππππ
)
Aver
age
Wai
ting
Tim
e of
Pe
rson
nel d
urin
g Sh
utdo
wn
Ratio
Wor
k or
der c
ompl
etio
n da
te β
(que
ry
star
t dat
e, q
uery
end
dat
e)
π΄π΄πππππππππ π ππ πππππ π π π π π πΆπΆπ π
πππ π ππππ ππππππ πππππππ π πππΆπΆπΆπΆππππ π π πππππ π πΆπΆπ π ππβπππ π π π πππ·π·πΆπΆ
π΄π΄πππππππππ π ππ πππππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππππ π πππ π ππ πππ π ππππ
Aver
age
Wai
ting
Tim
e fo
r Sp
are
Part
s dur
ing
Shut
dow
n Ra
tio
Wor
k or
der c
ompl
etio
n da
te β
(que
ry
star
t dat
e, q
uery
end
dat
e)
π΄π΄πππππππππ π ππ πππππ π π π π π πΆπΆπ π
πππ π ππππ ππππππ ππππππππππ πππππππ π π π π π πππππ π πΆπΆπ π
ππβπππ π π π πππ·π·
πΆπΆ π΄π΄πππππππππ π ππ πππππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππππ π πππ π ππ πππ π ππππ
Estim
ated
Tim
e vs
. Act
ual
Tim
e W
ork
orde
r com
plet
ion
date
β (q
uery
st
art d
ate,
que
ry e
nd d
ate)
π΄π΄πππππππππ π ππ πππππππΆπΆπΆπΆπππ π πΈπΈπΈπΈπππππππ π π π πππΆπΆ πππ π ππππβπ΄π΄πππππππππ π ππ ππππππππ πππππ π ππππ
πππ π ππππ
22
Resource Related
Tota
l Num
ber o
f Int
erna
l La
bour
Hou
rs
Wor
k or
der c
ompl
etio
n da
te β
(que
ry
star
t dat
e, q
uery
end
dat
e)
ππππππ
(π π πππ π π π π π π π πππππππ π ππππππππππππ
π»π»πππππππ π
)
Aver
age
Inte
rnal
Lab
our
Hou
rs U
sed
Wor
k or
der c
ompl
etio
n da
te β
(que
ry
star
t dat
e, q
uery
end
dat
e)
ππππππ
(π π πππ π π π π π π π πππππππ π ππππππππππππ
π»π»πππππππ π
)πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
Tota
l Num
ber o
f Ext
erna
l La
bour
Hou
rs
Wor
k or
der c
ompl
etio
n da
te β
(que
ry
star
t dat
e, q
uery
end
dat
e)
ππππππ
(π π πππ π π π π π π π πππππππ π ππππππππππππ
π»π»πππππππ π
)
Aver
age
Exte
rnal
Lab
our
Hou
rs U
sed
Wor
k or
der c
ompl
etio
n da
te β
(que
ry
star
t dat
e, q
uery
end
dat
e)
ππππππ
(π π πππ π π π π π π π πππππππ π ππππππππππππ
π»π»πππππππ π
) πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
Num
ber o
f Mat
eria
ls U
sed
Wor
k or
der c
ompl
etio
n da
te β
(que
ry
star
t dat
e, q
uery
end
dat
e)
ππππππ
(ππππππ
ππππππ ππππ
π π πππ π π π π π π π πππππππ π ππππππππππ πππππππ π π π )
Aver
age
Mat
eria
l Use
d W
ork
orde
r com
plet
ion
date
β (q
uery
st
art d
ate,
que
ry e
nd d
ate)
ππππππ
(ππππππ
ππππππ ππππ π π πππ π π π π π π π πππππππ π
ππππππππππ
πππππππ π π π
) πΆπΆπππππΆπΆπ π (πΆπΆπππππππππππ π πππ π
ππππππππ πππππ π ππππ
)
Cost Related
Tota
l Cos
t of E
xter
nal
Hum
an R
esou
rces
Use
d W
ork
orde
r reg
istr
atio
n da
te β
(que
ry
star
t dat
e, q
uery
term
inat
ion
date
) ππππππ
( π»π»ππππππππππ π π πππ π ππ
) β
(π π πππ π π π π π π π πππππ π π π πππΆπΆ ππππ
πΉπΉπππππππ π π π πΆπΆ
ππππππππππππ π»π»πππππππ π
)
Aver
age
Exte
rnal
Hum
an
Reso
urce
s Cos
ts
Wor
k or
der r
egis
trat
ion
date
β (q
uery
st
art d
ate,
que
ry te
rmin
atio
n da
te)
πππππ π ππππ πΆπΆπππ π π π ππππ πΈπΈπΈπΈπ π πππππΆπΆππππ
π»π»ππππ
πππΆπΆ π π πππ π πππππππππππ π
πππ π πππ π
πΆπΆπππππΆπΆπ π (πΆπΆπππππππππππ π πππ π
ππππππππ πππππ π ππππ
)ππβππππππ
π·π·ππππππ πππππ π πππ π ππππππ
=βπππΈπΈπ π πππππΆπΆππππβ
Tota
l Cos
t of M
ater
ials
Use
d W
ork
orde
r reg
istr
atio
n da
te β
(que
ry
star
t dat
e, q
uery
term
inat
ion
date
) ππππππ
π·π·π π π π π π π π πΆπΆπππ π πππ π π π πππ π
((ππππππππππ πππππππ π π π πππππππΆπΆπ π π π π π ππ)β
( ππππππππππ
πππππππ π π π
πππππ π ππππ
) )
Aver
age
Cost
of M
ater
ials
Us
ed
Wor
k or
der r
egis
trat
ion
date
β (q
uery
st
art d
ate,
que
ry te
rmin
atio
n da
te)
πππππ π ππππ πΆπΆπππ π π π ππππ πππππ π πππππ π ππππ ππ
π π πππ π
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
Exte
rnal
Lab
our C
osts
Rat
io
Wor
k or
der r
egis
trat
ion
date
β (q
uery
st
art d
ate,
que
ry te
rmin
atio
n da
te)
πππππ π ππππ πΆπΆπππ π π π ππππ πΈπΈπΈπΈπ π πππππΆπΆππππ
π»π»ππππ
πππΆπΆ π π πππ π πππππππππππ π
πππ π πππ π
(πππππ π ππππ
πΆπΆπππ π π π ππππ πΈπΈπΈπΈπ π πππππΆπΆππππ
π»π»ππππ
πππΆπΆ π π πππ π πππππππππππ π
πππ π πππ π
+ πππππ π ππππ
πΆπΆπππ π π π ππππ πππππ π πππππ π ππππ ππ
π π πππ π )
Actu
al M
ater
ials
Cos
t Rat
io
Wor
k or
der r
egis
trat
ion
date
β (q
uery
st
art d
ate,
que
ry te
rmin
atio
n da
te)
πππππ π ππππ πΆπΆπππ π π π ππππ πππππ π πππππ π ππππ ππ
π π πππ π
(πππππ π ππππ
πΆπΆπππ π π π ππππ πΈπΈπΈπΈπ π πππππΆπΆππππ
π»π»ππππ
πππΆπΆ π π πππ π πππππππππππ π
πππ π πππ π
+
πππππ π ππππ πΆπΆπππ π π π ππππ πππππ π πππππ π ππππ ππ
π π πππ π )
Mai
nten
ance
Cos
t per
Ass
et
Wor
k or
der r
egis
trat
ion
date
β (q
uery
st
art d
ate,
que
ry te
rmin
atio
n da
te)
ππππππ
(ππππππππππ
πππππππ π π π
πππππππΆπΆπ π π π π π ππ)
β (ππππππππππ πππππππ π π π πππππ π ππππ)
23
Maintenance Assessment
Quality N
umbe
r of C
ompl
eted
Wor
k Or
ders
App
rove
d W
ork
orde
r cre
atio
n da
te β
(que
ry st
art
date
, que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππππ πππππ π ππππ
) ππβππππππ
πππ π πππ π πππ π
=
β²ππππππ
πππππππ π ππβ²πππΆπΆπ π ππππ
_ππππππππ
= β²πππππππππππππππ π β²
Wor
k Or
der A
ppro
val R
atio
W
ork
orde
r cre
atio
n da
te β
(que
ry st
art
date
, que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππππ πππππ π ππππ
) ππβππππππ
ππππππππππππ
= β²πππππΈπΈπππ π ππππ
ππππππππππππππππβ²
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
ππππππππ πππππ π πππππ π )
One-
Tim
e Pa
ss In
tern
al
Com
plet
ion
Rate
W
ork
orde
r cre
atio
n da
te β
(que
ry st
art
date
, que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
ππππππππ πππππ π πππππ π )ππβππππππ
ππππππππππππ
= β²ππππππ
πππππππ π πππ π
ππππππ
ππππππππππππππππβ²
βπππππππππππππππ π πππΆπΆππππ
β πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
ππππππππ πππππ π πππππ π
) π·π·βππππππ
π·π·ππππππ π π ππππππππ
=β²π π πΆπΆπ π πππππΆπΆππππβ²
One-
Tim
e Pa
ss E
xter
nal
Com
plet
ion
Rate
W
ork
orde
r cre
atio
n da
te β
(que
ry st
art
date
, que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
ππππππππ πππππ π πππππ π )π·π·βππππππ
ππππππππππππ
= β²ππππππ
πππππππ π πππ π
ππππππ
ππππππππππππππππβ²
βπππππππππππππππ π
πππΆπΆππππβ
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
ππππππππ πππππ π πππππ π )
π·π·βππππππ
π·π·ππππππ π π ππππππππ
=β²πππΈπΈπ π πππππΆπΆππππβ²
Plan
ning
Com
plia
nce
Wor
k or
der c
reat
ion
date
β (q
uery
star
t da
te, q
uery
end
dat
e)
οΏ½πππππππΆπΆπΆπΆπππ π πππππΆπΆ
π»π»πππππππ π
πΆπΆππππ
πππππππ π πππ π
πππππ π ππππ ππ
ππππππππππ πππππππΆπΆπΆπΆπππ π πππππΆπΆ
π»π»πππππππ π
οΏ½β
100
Effectiveness
Inte
rnal
Wor
k Co
mpl
etio
n Ra
te
Plan
ned
wor
k or
der o
mpl
etio
n da
te β
(q
uery
star
t dat
e, q
uery
term
inat
ion
date
)
ππππππ
(πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
πΆπΆπππππΆπΆπ π (ππππππππ πππππ π πππππ π )ππβππππππ
π·π·πππππππ π ππππππππ
=β²πΌπΌπΆπΆπ π πππππΆπΆππππβ²
Outs
ourc
ed W
ork
Com
plet
ion
Rate
Plan
ned
wor
k or
der c
ompl
etio
n da
te β
(q
uery
star
t dat
e, q
uery
term
inat
ion
date
)
ππππππ
(πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
πΆπΆπππππΆπΆπ π (ππππππππ πππππ π πππππ π )ππβπππππππ·π·ππππππ π π ππππππππ
= β²πππΈπΈπ π πππππΆπΆππππβ²
Inte
rnal
Wor
k De
lay
Rate
W
ork
orde
r reg
istr
atio
n da
te β
(que
ry
star
t dat
e, q
uery
term
inat
ion
date
)
ππππππ
( ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
ππβππππππ
ππβ²πππ π π π π π π π πππππ π π π πππΆπΆ π π πππ π ππ
> πππππππΆπΆ πππππππππππππ π π π πππΆπΆ π π πππ π ππβ²
πΆπΆπππππΆπΆπ π (πΆπΆπππππππππππ π πππ π
ππππππππ πππππ π ππππ
ππππππ
ππππππ)
Inte
rnal
Wor
k Av
erag
e De
lay
Peri
od
Wor
k or
der r
egis
trat
ion
date
β (q
uery
st
art d
ate,
que
ry te
rmin
atio
n da
te)
πππππποΏ½
( π π πππ π π π π π π π πππππ π π π πππΆπΆ π·π·πππ π ππ)
β ( πππππππΆπΆπΆπΆπππ π
πΆπΆππππ
πππππππ π π π πππΆπΆ π·π·πππ π ππ)οΏ½
ππβππππππ
β²πππππ π π π π π π π πππππ π π π πππΆπΆ π π πππ π ππ
> πππππππΆπΆπΆπΆπππ π
ππππππ
πππππππ π π π πππΆπΆ π π πππ π ππβ²
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π )
ππβππππππ
β²πππππ π π π π π π π πππππ π π π πππΆπΆ π π πππ π ππ
> πππππππΆπΆπΆπΆπππ π
ππππππ
πππππππ π π π πππΆπΆ π π πππ π ππβ²
Exte
rnal
Wor
k D
elay
Rat
e W
ork
orde
r reg
istr
atio
n da
te β
(que
ry
star
t dat
e, q
uery
term
inat
ion
date
)
ππππππ
([ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
ππππππππ πππππ π πππππ π ]
ππβππππππ
β²πππππ π π π π π π π πππππ π π π πππΆπΆ π π πππ π ππ
> πππππππΆπΆ πππππππππππππ π π π πππΆπΆ π π πππ π ππβ²)
πΆπΆπππππΆπΆπ π (πΆπΆπππππππππππ π πππ π
ππππππππ πππππ π ππππ
ππππππ
ππππππ)
Exte
rnal
Wor
k Av
erag
e De
lay
Peri
od
Tick
et re
gist
ratio
n da
te β
(inq
uiry
star
t da
te, i
nqui
ry te
rmin
atio
n da
te)
ππππππ
( π π πππ π π π π π π π πππππ π π π πππΆπΆ π·π·πππ π ππ)
β ( πππππππΆπΆπΆπΆπππ π
πΆπΆππππ
πππππππ π π π πππΆπΆ π·π·πππ π ππ)
ππβππππππ
β²πππππ π π π π π π π πππππ π π π πππΆπΆ π π πππ π ππ
> πππππππΆπΆπΆπΆπππ π
ππππππ
πππππππ π π π πππΆπΆ π π πππ π ππβ²
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΆπΆππππ
πππππππ π πππ π
πππππ π πππππ π )
ππβππππππ
β²πππππ π π π π π π π πππππ π π π πππΆπΆ π π πππ π ππ
> πππππππΆπΆ πππππππππππππ π π π πππΆπΆ π π πππ π ππβ²
Inte
rnal
Ave
rage
Exe
cutio
n Ti
me
Dev
iatio
n Ra
tio
Wor
k or
der c
reat
ion
date
(dat
e of
in
quir
y, d
ate
of in
quir
y te
rmin
atio
n)
( πΌπΌπΆπΆπ π πππππΆπΆππππ ππ
πππππππ π πΆπΆπ π
π΄π΄πππππππππ π ππ
π΄π΄πππ π ππππππ πΈπΈπΈπΈπππππππ π π π πππΆπΆ
πππ π ππππ)
β (πΌπΌπΆπΆπ π πππππΆπΆππππ ππ
πππππππ π πΆπΆπ π
π΄π΄πππππππππ π ππ
πππππππΆπΆπΆπΆπππ π
πΈπΈπΈπΈπππππππ π π π πππΆπΆ
πππ π ππππ)
(πΌπΌπΆπΆπ π πππππΆπΆππππ ππ
πππππππ π πΆπΆπ π
π΄π΄πππππππππ π ππ
πππππππΆπΆπΆπΆπππ π
πΈπΈπΈπΈπππππππ π π π πππΆπΆ
πππ π ππππ)
24
Exte
rnal
Com
mitt
ee
Exec
utio
n Ti
me
Dev
iatio
n Ra
tio
Wor
k or
der c
reat
ion
date
(dat
e of
in
quir
y, d
ate
of in
quir
y te
rmin
atio
n)
( πΈπΈπΈπΈπ π πππππΆπΆππππ ππ
πππππππ π πΆπΆπ π
π΄π΄πππππππππ π ππ
π΄π΄πππ π ππππππ πΈπΈπΈπΈπππππππ π π π πππΆπΆ
πππ π ππππ)
β (πΈπΈπΈπΈπ π πππππΆπΆππππ ππ
πππππππ π πΆπΆπ π
π΄π΄πππππππππ π ππ
πππππππΆπΆπΆπΆπππ π
πΈπΈπΈπΈπππππππ π π π πππΆπΆ
πππ π ππππ)
πΈπΈπΈπΈπ π πππππΆπΆππππ
πππππππππ π πΆπΆπ π
π΄π΄πππππππππ π ππ
πππππππΆπΆπΆπΆπππ π
πΈπΈπΈπΈπππππππ π π π πππΆπΆ
πππ π ππππ
Inte
rnal
Man
-Hou
r Di
ffere
nce
Ratio
W
ork
orde
r cre
atio
n da
te (d
ate
of
inqu
iry,
dat
e of
inqu
iry
term
inat
ion)
ππππππ
( π π πππ π π π π π π π πππππ π π π πππΆπΆ ππππππππππππ
πππ π ππππ)β
ππππππ
(πππππππΆπΆπΆπΆπππ π
ππππππππππππ πππ π ππππ)
ππππππ
(πππππππΆπΆπΆπΆπππ π
ππππππππππππ πππ π ππππ)
Inte
rnal
Ave
rage
Man
-Hou
r Di
ffere
nce
Ratio
W
ork
orde
r cre
atio
n da
te (d
ate
of
inqu
iry,
dat
e of
inqu
iry
term
inat
ion)
( πΌπΌπΆπΆπ π πππππΆπΆππππ π΄π΄πππππππππ π ππ
ππππππππππππ πππ π ππππ)β
(πΌπΌπΆπΆπ π πππππΆπΆππππ π΄π΄πππππππππ π ππ
πππππππΆπΆ ππππππππππππ
πππ π ππππ)
πΌπΌπΆπΆπ π πππππΆπΆππππ
π΄π΄πππππππππ π ππ
πππππππΆπΆ ππππππππππππ
πππ π ππππ
Exte
rnal
Man
-Hou
r Di
ffere
nce
Ratio
W
ork
orde
r cre
atio
n da
te (d
ate
of
inqu
iry,
dat
e of
inqu
iry
term
inat
ion)
ππππππ
( π π πππ π π π π π π π πππππ π π π πππΆπΆ ππππππππππππ
πππ π ππππ)β
ππππππ
(πππππππΆπΆπΆπΆπππ π
ππππππππππππ πππ π ππππ)
ππππππ
(πππππππΆπΆπΆπΆπππ π
ππππππππππππ πππ π ππππ)
Exte
rnal
Ave
rage
Man
-Hou
r Di
ffere
nce
Ratio
W
ork
orde
r cre
atio
n da
te (d
ate
of
inqu
iry,
dat
e of
inqu
iry
term
inat
ion)
(πΈπΈπΈπΈπ π πππππΆπΆππππ π΄π΄πππππππππ π ππ
ππππππππππππ πππ π ππππ)
β(πΈπΈπΈπΈπ π πππππΆπΆππππ π΄π΄πππππππππ π ππ
πππππππΆπΆ ππππππππππππ
πππ π ππππ)
(πΈπΈπΈπΈπ π πππππΆπΆππππ π΄π΄πππππππππ π ππ
πππππππΆπΆ ππππππππππππ
πππ π ππππ)
Mat
eria
ls D
iffer
ence
Rat
io
Wor
k or
der c
reat
ion
date
(dat
e of
in
quir
y, d
ate
of in
quir
y te
rmin
atio
n)
ππππππ
(π π πππ π π π π π π π πππππππ π ππππππππππ πππππππ π π π )
β ππππππ
(ππππβπππ π πππππππ π
ππππππππππ
πππππππ π )
ππππππ
(ππππβπππ π πππππππ π
ππππππππππ
πππππππ π )
Aver
age
Mat
eria
ls
Diffe
renc
e Ra
tio
Wor
k or
der c
reat
ion
date
(dat
e of
in
quir
y, d
ate
of in
quir
y te
rmin
atio
n)
π΄π΄πππππππππ π ππ
(π π πππ π π π π π π π πππππππ π ππππππππππ πππππππ π π π )
β π΄π΄πππππππππ π ππ
(ππππβπππ π πππππππ π
ππππππππππ
πππππππ π π π
)π΄π΄πππππππππ π ππ
(ππππβπππ π πππππππ π
ππππππππππ
πππππππ π π π
)
Tabl
e 6:
Impl
emen
tatio
n us
ing
eMai
nten
ance
for M
aint
enan
ce R
esou
rce
Man
agem
ent
Le
vel
Nam
e Ti
mel
ine
Gene
ral F
orm
ula
3 4
Spare Parts Management
Inventory Management
Aver
age
Spar
e Pa
rt Q
uant
ity
Spar
e pa
rts s
tock
dat
e (q
uery
star
t da
te, q
uery
end
dat
e)
([πππππππΆπΆπ π πΆπΆπ π
πππ π ππππππ
] +
[πΈπΈπΆπΆπ π π π πΆπΆπ π
πππ π ππππππ
) 2
Spar
e Pa
rt C
apita
l Util
izat
ion
equi
pmen
t led
ger d
ate(
quer
y st
art
date
, que
ry e
nd d
ate)
ππππππππππ πππππππ π π π πΌπΌπΆπΆπππππΆπΆπ π ππππππ πΉπΉπππΆπΆπ π π π
ππππππ
(πΈπΈπΈπΈπππ π πππππππΆπΆπ π ππ
ππππππβπππ π ππ πππππ π ππππ)
Spar
e Pa
rts C
apita
l Rep
lace
men
t Rat
e eq
uipm
ent l
edge
r dat
e(qu
ery
star
t da
te, q
uery
end
dat
e)
ππππππππππ πππππππ π π π πΌπΌπΆπΆπππππΆπΆπ π ππππππ πΉπΉπππΆπΆπ π π π
ππππππ
(πΈπΈπΈπΈπππ π πππππππΆπΆπ π π π
πππππππππππππππππΆπΆπ π πΆπΆπππ π π π )
Spar
e Pa
rt C
onsu
mpt
ion
per T
hous
and
Sek
Outp
ut
Wor
k or
der r
egis
trat
ion
date
β (q
uery
st
art d
ate,
que
ry e
nd d
ate)
ππππππ
(πππππ π ππππ
πΆπΆπππ π π π ππππ ππππππππππ πππππππ π π π πΆπΆπππΆπΆπ π ππππ
πππ π π π πππΆπΆ)
πππππ π ππππ πππππ π πππππ π ππ
ππππππππ
ππππππ
100
0 ππππππ πππππ π πππππ π
Spar
e Pa
rt T
urno
ver R
ate
Wor
k or
der r
egis
trat
ion
date
β (q
uery
st
art d
ate,
que
ry e
nd d
ate)
ππππππ
(πππππ π ππππ
πΆπΆπππ π π π ππππ ππππππππππ πππππππ π π π πΆπΆπππΆπΆπ π ππππ
πππ π π π πππΆπΆ)
π΄π΄πππππππππ π ππ ππππππππππ πππππππ π π π πΌπΌπΆπΆπππππΆπΆπ π ππππππ πΉπΉπππΆπΆπ π π π
Spar
e Pa
rt T
urno
ver P
erio
d W
ork
orde
r reg
istr
atio
n da
te β
(que
ry
star
t dat
e, q
uery
end
dat
e)
π΄π΄πππππππππ π ππ ππππππππππ πππππππ π π π πΌπΌπΆπΆπππππΆπΆπ π ππππππ πΉπΉπππΆπΆπ π π π
ππππππ
(πππππ π ππππ
πΆπΆπππ π π π ππππ ππππππππππ πππππππ π π π πΆπΆπππΆπΆπ π ππππ
πππ π π π πππΆπΆ)β
365
Slow
Mov
ing
Inve
ntor
y Ra
tio
equi
pmen
t led
ger d
ate(
quer
y st
art
date
, que
ry e
nd d
ate)
ππππππ
ππππππ ππππ
ππππππππππ
πππππππ π π π
πππππ π
πππ π πππ π
πππππ π ππππ ππ
ππππππππππ ππππ
ππππππππππ
25
Outsourcing Management
Contractor Statistics
Num
ber o
f Out
sour
ced
Equi
pmen
t Br
eakd
owns
W
ork
supp
lier l
ist d
ate β
(que
ry st
art
date
, que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
π π πππ π π π π π π π πππππππ π πππ π πππππ π )
ππβππππππ
π π π π β²ππ
πππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππππππ π πππΆπΆπΆπΆππππβ² &
βπππππ π π π πππππππππππ π β
)
Num
ber o
f Out
sour
ced
Mai
nten
ance
Pe
rson
nel
Wor
k su
pplie
r lis
t dat
e β
(que
ry st
art
date
, que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπππππππππππππππ π )
ππβππππππ
π π π π β²ππ
πππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππππππ π πππΆπΆπΆπΆππππβ² &
βπππππ π π π πππππππππππ π β
)
Exte
rnal
Mai
nten
ance
Cos
t Rat
io
Wor
k su
pplie
r lis
t dat
e β
(que
ry st
art
date
, que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπΈπΈπ π πππππΆπΆππππ πππππππ π πππΆπΆπΆπΆππππ
) β
(π π πππ π ππ ππππ
ππππππππ π·π·πππΆπΆππ)
πππππ π ππππ ππ
πππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πΆπΆπππ π π π
β10
0
Human Resources Management
Skills Management
Tota
l Num
ber o
f Mai
nten
ance
Ope
rato
rs
Wor
k su
pplie
r lis
t dat
e β
(que
ry st
art
date
, que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπππππππππππππππ π )
ππβππππππ
π π π π β²ππ
πππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππππππ π πππΆπΆπΆπΆππππβ² &
β²πππππππππππ π ππππβ²
Tota
l Num
ber o
f Mai
nten
ance
Eng
inee
rs
Wor
k su
pplie
r lis
t dat
e β
(que
ry st
art
date
, que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπππππππππππππππ π )
π·π·βππππππ
π π π π β²ππ
πππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππππππ π πππΆπΆπΆπΆππππβ² &
β²πππΆπΆπ π π π πΆπΆππππππβ²
Num
ber o
f Mul
ti-Sk
illed
Mai
nten
ance
Pe
rson
nel
Wor
k su
pplie
r lis
t dat
e β
(que
ry st
art
date
, que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπππππππππππππππ π )
ππβππππππ
π π π π β²ππ
πππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππππππ π πππΆπΆπΆπΆππππβ² &
β²πππππππ π π π βπ π πππ π ππππβ²
Mai
nten
ance
Ope
rato
r Rat
e W
ork
supp
lier l
ist d
ate β
(que
ry st
art
date
, que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπππππππππππππππ π )
ππβππππππ
π π π π β²ππ
πππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππππππ π πππΆπΆπΆπΆππππβ² β²πππππππππππ π ππππβ²
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπππππππππππππππ π )
β10
0
Mai
nten
ance
Eng
inee
r Rat
e W
ork
supp
lier l
ist d
ate β
(que
ry st
art
date
, que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπππππππππππππππ π )
ππβππππππ
π π π π β²ππ
πππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππππππ π πππΆπΆπΆπΆππππβ² β²πππΆπΆπ π π π πΆπΆππππππβ²
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπππππππππππππππ π )
β10
0
Mul
ti-Sk
illed
Mai
nten
ance
Per
sonn
el
Rate
W
ork
supp
lier l
ist d
ate β
(que
ry st
art
date
, que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπππππππππππππππ π )
ππβππππππ
π π π π β²ππ
πππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππππππ π πππΆπΆπΆπΆππππβ² β²πππππππ π π π βπ π πππ π ππππβ²
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπππππππππππππππ π )
β10
0
Work Load Management
Aver
age
Num
ber o
f Wor
k Or
ders
Cr
eate
d pe
r Per
son
Wor
k or
der c
reat
ion
date
β (q
uery
st
art d
ate,
que
ry e
nd d
ate)
ππππππ
(πΆπΆππππ
ππππππ ππππ
π·π·ππππππ πππππ π πππππ π
)πΆπΆπππππΆπΆπ π (πΆπΆππππππππππ ππππ
πππππππππππππππππ π )
ππβππππππ
π π π π βπππππ π πππππΆπΆπ π π π ππππππ
ππππππ
π·π·ππππππ πππππ π ππππ πππππππππ π π π πππΆπΆ
β
Aver
age
Num
ber o
f Wor
k Or
ders
Ex
ecut
ed p
er P
erso
n W
ork
orde
r cre
atio
n da
te β
(que
ry
star
t dat
e, q
uery
end
dat
e)
ππππππ
(ππππππ
ππππππ ππππ
ππππππππ)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπππππππππππππππ π )
ππβππππππ
π π π π βπππππ π πππππΆπΆπ π π π ππππππ
ππππππ
π·π·ππππππ πππππ π ππππ πππΈπΈπππππππ π π π πππΆπΆβ
Aver
age
Daily
Wor
kloa
d pe
r Per
son
Wor
k or
der c
reat
ion
date
β (q
uery
st
art d
ate,
que
ry e
nd d
ate)
ππππππ
(π π πππ π π π π π π π πππππππ π π»π»πππππππ π
) πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπππππππππππππππ π )
ππβππππππ
π π π π βπππππ π πππππΆπΆπ π π π ππππππ
ππππππ
π·π·ππππππ πππππ π ππππ πππΈπΈπππππππ π π π πππΆπΆβ
β
(ππππππ
ππππππ ππππ
π·π·πππππ π π π πππππ π πΆπΆπ π
πΌπΌπΆπΆπΈπΈπππ π ππππ)
26
Training Management
Aver
age
Annu
al T
rain
ing
Hou
rs p
er
Mai
nten
ance
Ope
rato
r W
ork
orde
r cre
atio
n da
te β
(que
ry
star
t dat
e, q
uery
end
dat
e)
ππππππ
(π π πππ π π π π π π π πππππππ π π»π»πππππππ π
) πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπππππππππππππππ π )
ππβππππππ
π π π π β²ππ
πππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππππππ π πππΆπΆπΆπΆππππβ² β²πππππππππππ π ππππβ²
β36
5
Aver
age
Annu
al T
rain
ing
Hou
rs p
er
Mai
nten
ance
Eng
inee
rs
Wor
k or
der c
reat
ion
date
β (q
uery
st
art d
ate,
que
ry e
nd d
ate)
ππππππ
( π π πππ π π π π π π π πππππππ π π»π»πππππππ π
)πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπππππππππππππππ π )
ππβππππππ
π π π π β²ππ
πππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππππππ π πππΆπΆπΆπΆππππβ² β²πππΆπΆπ π π π πΆπΆππππππβ²
β36
5
Aver
age
Annu
al T
rain
ing
Hou
rs p
er
Mul
ti-Sk
illed
Mai
nten
ance
Eng
inee
rs
Wor
k or
der c
reat
ion
date
β (q
uery
st
art d
ate,
que
ry e
nd d
ate)
ππππππ
(π π πππ π π π π π π π πππππππ π π»π»πππππππ π
)πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπππππππππππππππ π )
ππβππππππ
π π π π β²ππ
πππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππππππ π πππΆπΆπΆπΆππππβ² β²πππππππ π π π βπ π πππ π πππππππ π β²β
365
Competence Development
Num
ber o
f New
Sen
ior M
aint
enan
ce
Engi
neer
s W
ork
supp
lier l
ist d
ate β
(que
ry st
art
date
, que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπππππππππππππππ π )
ππβππππππ
π π π π β²ππ
πππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππππππ π πππΆπΆπΆπΆππππβ² &
β²πππππππππππ π ππππβ²
& πππππ·π·
π π ππππππ
=
βπππππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππΆπΆπ π π π πΆπΆππππππβ
Perc
enta
ge o
f New
Sen
ior M
aint
enan
ce
Engi
neer
s W
ork
supp
lier l
ist d
ate β
(que
ry st
art
date
, que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπππππππππππππππ π )
ππβππππππ
π π π π β²ππ
πππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππππππ π πππΆπΆπΆπΆππππβ² &
β²πππππππππππ π ππππβ²
& πΆπΆπππ·π·
ππππππππ
=
βπππππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππΆπΆπ π π π πΆπΆππππππβ
β 1
00
Num
ber o
f New
Mul
ti-Sk
illed
M
aint
enan
ce E
ngin
eers
W
ork
supp
lier l
ist d
ate β
(que
ry st
art
date
, que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπππππππππππππππ π )
ππβππππππ
π π π π β²ππ
πππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππππππ π πππΆπΆπΆπΆππππβ² &
β²πππππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππΆπΆπ π π π πΆπΆππππππβ²
) &
(πΆπΆπππ·π·
ππππππππ
=βπππππππ π π π βπ π πππ π πππππππ π
πππππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππΆπΆπ π π π πΆπΆππππππβ
)
Perc
enta
ge o
f New
Mul
ti-Sk
illed
M
aint
enan
ce E
ngin
eers
W
ork
supp
lier l
ist d
ate β
(que
ry st
art
date
, que
ry e
nd d
ate)
πΆπΆπππππΆπΆπ π (ππππππ
ππππππ ππππ
πΈπΈπππππππππππππππ π )
ππβππππππ
π π π π β²ππ
πππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππππππ π πππΆπΆπΆπΆππππβ² &
β²πππππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππΆπΆπ π π π πΆπΆππππππβ²
) πππΆπΆπ π
(πΆπΆπππ·π·
ππππππππ
=βπππππππ π π π βπ π πππ π πππππππ π
πππππ π πΆπΆπ π πππΆπΆπππΆπΆππππ
πππΆπΆπ π π π πΆπΆππππππβ
) β
100
27
7. Discussion The frameworks and approaches highlighted in Section 1 cannot solve the problems of the case study mining company. In terms of technical KPIs, it is at the top of its game, possibly because measuring the performance of machines is not as complicated as measuring the maintenance process. With the right configuration and devices, censors can make measurements automatically with little human involvement. However, the company does not have a way to measure soft KPIs.
Our proposed KPI framework has 111 soft KPIs, 85 for the maintenance process and 26 for maintenance resources. Following the maintenance process in the IEV standard, this KPI framework provides KPIs to measure maintenance strategy, maintenance planning, maintenance preparation, maintenance execution and maintenance assessment. These form the basis of the maintenance process. Thus, the proposed system is a more holistic performance measurement system; it will be beneficial to this mining organization, as there are some dependencies between soft KPIs and other organizational KPIs as shown in Figure 2.
Figure 2: Dependencies between Organizational KPIs
Soft KPIs can affect the technical KPIs in the long run and increase or decrease utilization and plant speed. When utilization and plant speed decrease, total production output will also decrease. In some cases, quality can be affected. Thus, both the soft KPIs and the technical KPIs affect the production KPIs. The values of the soft and technical KPIs reflect how well maintenance activities are going. Ineffective maintenance will not give optimal production and can affect the quality of the product, in this case, iron ore, and/or reduce production times because of breakdowns. Poor production, in turn, will not give good manufacturing execution system (MES) KPIs. This will eventually reduce the marketing KPI values, as customers will not buy products that are not of the highest quality for high prices, and the companyβs overall KPIs will suffer. Each KPI in the proposed framework has a relationship of some kind with the KPIs
Overall KPIs
Marketing KPIs
Manufacturing Execution
System KPIs
Production KPIs
Technical KPIs
Soft KPIs
28
above and below it; thus, changes in one KPI have a ripple effect on other KPIs. Recognizing appropriate soft KPIs and improving their values will increase overall capacity utilization, not just in maintenance but in all areas of the organization.
8. Conclusions This study proposes a KPI framework for maintenance management in a mining company. This KPI framework comprises two parts: technical KPIs (linked to machines) and business KPIs (linked to workflow); the latter ones are also called βsoft KPIsβ internally. The developed KPI framework has four levels. One the second levels are Asset Operation Management which deals with KPIs that measure maintenance performance relative to the equipment condition, Maintenance Process Management which deals with KPIs that measure efficiency and effectiveness of the consistent application of maintenance and maintenance support and Maintenance Resources Management which deals with KPIs that measure spare part management, internal maintenance personnel management and external maintenance personnel management. The third level shows a further breakdown of the items on the second level while the fourth level shows the KPIs that are made up of the third level classifications. The proposed KPI framework presents 134 KPIs that can be used to measure maintenance performance and streamline maintenance processes. Twenty-three KPIs are technical and 111 are soft. For the latter, 85 KPIs are for maintenance process management and 26 are for maintenance resources management. The study suggests soft KPIs can help to track maintenance strategy, maintenance planning, preparation and execution; they can also show how well maintenance tasks are achieved and track the use of resources, including internal and external maintenance personnel and spare parts for maintenance tasks. Ultimately, an integrated KPI approach will increase the decision makerβs awareness of maintenance performance, enhancing his or her decision-making abilities. Besides the proposed KPI framework, another contribution in this study is addressing its implementation by introducing time definition and general formula of each specified KPI. Results from this study will be applied to the studied company and supply the guidance of implementing those KPIs through eMaintenance.
Acknowledgements The motivation for the research originated from the project βKey Performance Indicators (KPI) for control and management of maintenance process through eMaintenance (In Swedish: Nyckeltal fΓΆr styrning och uppfΓΆljning av underhΓ₯llsverksamhet m h a eUnderhΓ₯ll)β, initiated and financed by LKAB. The authors wish to thank Peter Olofsson, Mats Renfors, Sylvia Simma, Maria Rytty, Mikael From and Johan Enbak, for their support for this research in the form of funding and work hours.
29
References
Al-Najjar, B. (2007). The lack of maintenance and not maintenance which costs: A model to describe and quantify the impact of vibration-based maintenance on company's business. International Journal of Production Economics, 107(1), 260-273.
Bourne, M., Melnyk, S., & Bititci, U. S. (2018). Performance measurement and management: Theory and practice. International Journal of Operations & Production Management, 38(11), 2010-2021.
Bourne, M., Mills, J., Wilcox, M., Neely, A., & Platts, K. (2000). Designing, implementing and updating performance measurement systems. International Journal of Operations & Production Management, 20(7), 754-771.
Campbell, J. D., & Reyes-Picknell, J. (2006). Strategies for excellence in maintenance management Productivity Press.
Coetzee, J. (1997). Towards a general maintenance model. Proceedings of IFRIM β97, , 1-9.
Dwight, R. (1995). Concepts for measuring maintenance performance. New Developments in Maintenance, , 109-125.
Dwight, R. (1999a). Frameworks for measuring the performance of the maintenance system in a capital intensive organisation.
Dwight, R. (1999b). Searching for real maintenance performance measures. Journal of Quality in Maintenance Engineering, 5(3), 258-275.
Jayaratna, N. (1994). Understanding and evaluating methodologies: NIMSAD, a systematic framework McGraw-Hill, Inc.
Kaplan, R. S., & Norton, D. P. (1992). The balanced scorecard--measures that drive performance. Harvard Business Review, 70(1), 71-79. Retrieved from http://search.proquest.com/docview/73114889?accountid=27917
Kumar, U., & Ellingson, H. (2000). Development and implementation of maintenance performance indicators for the norweigan oil and gas industry. Paper presented at the Development and Implementation of Maintenance Performance Indicators for the Norweigan Oil and Gas Industry: 07/03/2000-10/03/2000, 221-228.
Kumar, U., Galar, D., Parida, A., StenstrΓΆm, C., & Berges, L. (2013). Maintenance performance metrics: A State-of-the-Art review. J of Qual in Maintenance Eng, 19(3), 233-277. doi:10.1108/JQME-05-2013-0029
Lingle, J. H., & Schiemann, W. A. (1996). From balanced scorecard to strategic gauges: Is measurement worth it? Management Review, 85(3), 56.
LΓΆfsten, H. (2000). Measuring maintenance performanceβin search for a maintenance productivity index. International Journal of Production Economics, 63(1), 47-58.
Muchiri, P., Pintelon, L., Gelders, L., & Martin, H. (2011). Development of maintenance function performance measurement framework and indicators. International Journal of Production Economics, 131(1), 295-302.
Neely, A. (1999). The performance measurement revolution: Why now and what next? International Journal of Operations & Production Management, 19(2), 205-228.
Parida, A., & Chattopadhyay, G. (2007). Development of a multi-criteria hierarchical framework for maintenance performance measurement (MPM). Journal of Quality in Maintenance Engineering, 13(3), 241-258.
Parmenter, D. (2007). Key performance indicators: Developing, implementing, and using winning KPIs John Wiley & Sons.
Tsang, A. H. (2000). Maintenance performance management in capital intensive organizations (PhD Thesis).
Weber, A., & Thomas, R. (2005). Key performance indicators: Measuring and managing the maintenance function. Ivara Corporation.
PaperB
System availability assessment using a parametric Bayesian approach β a case study of balling drums
Saari, E., Lin, J., Zhang, L-W, Liu B and Karim, R. 2019. System availability assessment using a parametric Bayesian approach β a case study of balling drums. InternationalJournalofSystemAssuranceEngineeringandManagement.Accepted.
1
SystemavailabilityassessmentusingaparametricBayesianapproach
A case study of balling drums
Esi Saari1, Jing Lin1*, Liangwei Zhang1,2, Bin Liu3, Ramin Karim1
1. DivisionofOperationandMaintenanceEngineering,LuleΓ₯UniversityofTechnology,LuleΓ₯,Sweden;2. DepartmentofIndustrialEngineering,DongguanUniversityofTechnology,Dongguan,China;3. DepartmentofManagementScience,UniversityofStrathclyde,Glasgow,UK.
*Correspondingauthor;Eβmailaddress:[email protected]
Abstract:Assessment of system availability usually uses either an analytical (e.g., Markov/semi-Markov) or a simulation approach (e.g., Monte Carlo simulation-based). However, the former cannot handle complicated state changes and the latter is computationally expensive. Traditional Bayesian approaches may solve these problems; however, because of their computational difficulties, they are not widely applied. The recent proliferation of Markov Chain Monte Carlo (MCMC) approaches have led to the use of the Bayesian inference in a wide variety of fields. This study proposes a new approach to system availability assessment: a parametric Bayesian approach using MCMC, an approach that takes advantages of the analytical and simulation methods. By using this approach, Mean Time to Failure (MTTF) and Mean Time to Repair (MTTR) are treated as distributions instead of being βaveragedβ, which better reflects reality and compensates for the limitations of simulation data sample size. To demonstrate the approach, the paper considers a case study of a balling drum system in a mining company. In this system, MTTF and MTTR are determined in a Bayesian Weibull model and a Bayesian lognormal model respectively. The results show that the proposed approach can integrate the analytical and simulation methods to assess system availability and could be applied to other technical problems in asset management (e.g., other industries, other systems).
Keywords: Asset management, system availability, reliability, maintainability, Bayesian statistics; Markov Chain Monte Carlo (MCMC), mining industry.
1. Introduction
Availability represents the proportion of a systemβs uptime out of the total time in service and is one of the most critical aspects of performance evaluation. Availability is commonly measured as Mean Time to Failure (MTTF) and Mean Time to Repair (MTTR). However, those βmeanβ values are normally βaveragedβ; thus, some useful information (e.g., trends, system complexity) may be neglected, and some problems may even be hidden.
Assessment of system availability has been studied from the design stage to the operational stage in various system configurations (e.g., in series, parallel, k-out-of-n, stand-by, multi-state, or mixed architectures). Approaches to assessing system availability mainly use either analytic or simulation techniques.
In general, analytic techniques represent the system using direct mathematical solutions from applied probability theory to make statements on various performance measures, such as the
2
steady-state availability or the interval availability (Dekker & Groenendijk, 1995) (Ocnasu, 2007). Researchers tend to use Markov models to assess dynamic availability or semi-Markov models using Laplace transforms to determine average performance measures (Dekker & Groenendijk, 1995) (Faghih-Roohi, et al., 2014). However, such approaches have been criticised as too restrictive to tackle practical problems; they assume constant failure and repair rates which is not likely to be the case in the real world (Raje, et al., 2000) (Marquez, et al., 2005). Furthermore, the time dependent availability obtained by a Markovian assumption is actually not valid for non-Markovian processes (Raje, et al., 2000).
Simulation techniques estimate availability by simulating the actual process and random behaviour of the system. The advantage is that non-Markov failures and repair processes can be modelled easily (Raje, et al., 2000). Recent research is working on developing Monte Carlo techniques to model the behaviour of complex systems under realistic time-dependent operational conditions (Marquez, et al., 2005) (Marquez & Iung, 2007) (Yasseri & Bahai, 2018) or to model multi-state systems with operational dependencies (Zio, et al., 2007). Although simulation is more flexible, it is computationally expensive.
Traditionally, Bayesian approaches have been used to assess system availability as they can solve the problem of complicated system state changes and computationally expensive simulation data; however, their development and application were stalled by the strict assumptions on prior forms and by computational difficulties. Research is more concerned with the priorβs selection or the posteriorβs computation than the reality (Brender, 1968) (Brender, 1968) (Kuo, 1985) (Sharma & Bhutani, 1993) (Khan & Islam, 2012).
The recent proliferation of Markov Chain Monte Carlo (MCMC) simulation techniques has led to the use of the Bayesian inference in a wide variety of fields. Because of MCMCβs high dimensional numerical integral calculation (Lin, 2014), the selection of prior information and descriptions of reliability/maintainability can be more flexible and more realistic.
This study proposes a new approach to system availability assessment: a parametric Bayesian approach with MCMC, with a focus on the operational stage, using both analytical and simulation methods. MTTF or MTTR are treated as distributions instead of being βaveragedβ by point estimation, and this is closer to reality; in addition, the limitations of simulation data sample size are addressed by using MCMC techniques.
The rest of this paper is organized as follows. Section 2 describes the problem statement, the balling drum system, the data preparation, and the preliminary analysis of failure and repair data. Section 3 proposes a Bayesian Weibull model for MTTF and a Bayesian lognormal model for MTTR and explains how to use an MCMC computational scheme to obtain the parametersβ posterior distributions. Section 4 presents a case study, results, and discussion. Section 5 offers conclusions and suggestions for further study.
2. Problemstatement
This section presents the study problem statement, the balling drum system and its configuration, the system availability framework, and data preparation; it performs a
3
preliminary analysis of failure and repair data based on which parametric Bayesian models are constructed subsequently.
2.1Ballingdrumsystemsintheminingindustry
Our study is motivated by a balling drum system in the mining industry. The case study mine consists of five balling drums, labelled 1-5 (see Figure.1). All five balling drums receive their feed for production in the same manner. Each balling drum is expected to produce the same amount of pellets at its maximum. According to the working mechanism and an i. i. d test, they are regarded as independent; if one of the balling drums breaks down, it does not affect the rest of the balling drums, except that total production will be reduced. One assumption is made here that the system will fail only if all subsystems fail; therefore, it is treated as a parallel system.
Balling drum 1
Balling drum 2
Balling drum 3
Balling drum 4
Balling drum 5
Figure.1 Description of a balling drum and the system sketch
The availability of a single balling drum, denoted as A , can be computed by
π΄ππππΉ
ππππΉ ππππ 1
According to the assumption, the total system availability, A , can be calculated as
π΄ 1 1 π΄ 2
2.2Datapreparationandpreliminaryanalysis
The study uses the failure and repair data of the five balling drums from January 2013 to December 2018. There are 1782 records. In the first step, the null values are removed, and the data are reduced to 1774 records.
The next step reveals there are different reasons for the TTF and TTR of individual balling drums. It is noticed that, for TTR data, if 150 shutdowns are considered normal (denoted as a threshold, see Figure. 2), then those exceeding 150 should be treated as abnormal and investigated using Root Cause Analysis (RCA).
4
After checking the work order types of such kind of abnormal data, it is found that most of them are caused by βpreventive maintenanceβ which may due to lack of maintenance resources. To simplify the study, we assume all maintenance resources are sufficient for βpreventive maintenanceβ; thus, the abnormally data might be caused by shortage of spare parts or skilled personnel will not be treated specially in this paper.
Figure.2 Example of TTR data for balling drum 1
To determine the baseline distribution of Time to Failure (TTF) and Time to Repair (TTR), we conduct a preliminary study of failure data and repair data using traditional analysis. In this preliminary study, several distributions are considered: exponential distribution, Weibull distribution, normal distribution, log-logistic distribution, lognormal distribution, and extreme value distribution. Table 1 lists the results.
Table.1 Preliminary study of failure data and repair data
BallingdrumTTFfitness TTRfitness
1st 2nd 3rd 1st 2nd 3rd 1 Weibull Log-logistic Lognormal Lognormal Weibull Logistic 2 Weibull Log-logistic Lognormal Lognormal Weibull Logistic 3 Weibull Log-logistic Lognormal Lognormal Weibull Logistic 4 Weibull Log-logistic Lognormal Lognormal Weibull Logistic 5 Weibull Log-logistic Lognormal Lognormal Weibull Logistic
Based on the results, the Weibull distribution and lognormal distribution are selected for the TTF and TTR for balling drums 1 to 5; these are applied to the parametric Bayesian models in the next section.
5
3. ParametricBayesianModels
This section proposes a Bayesian Weibull model for TTF and a Bayesian lognormal model for TTR in the proposed parametric Bayesian models and explains the procedure of MCMC computational scheme to obtain the posterior distributions.
3.1MarkovChainMonteCarlowithGibbssampling
The recent proliferation of Markov Chain Monte Carlo (MCMC) approaches has led to the use of the Bayesian inference in a wide variety of fields. MCMC is essentially Monte Carlo integration using Markov chains. Monte Carlo integration draws samples from the required distribution and then forms sample averages to approximate expectations. MCMC draws out these samples by running a cleverly constructed Markov chain for a long time. There are many ways of constructing these chains. The Gibbs sampler is one of the best known MCMC sampling algorithms in the Bayesian computational literature. It adopts the thinking of βdivide and conquerβ: i.e., when a set of parameters must be evaluated, the other parameters are assumed to be fixed and known. Let ΞΈ be an i-dimensional vector of parameters, and let f ΞΈ denote the marginal distribution for the j th parameter. The basic scheme of the Gibbs sampler for sampling from p ΞΈ is given as follows:
Step 1. Choose an arbitrary starting point π π , β¦ , π ;
Step 2. Generate π from the conditional distribution π π |π , β¦ , π , and
generate π from the conditional distribution distribution π π |π , π , β¦ , π ;
Step 3. Generate π from π π |π , β¦ , π , π β¦ , π ;
Step 4. Generate π from π π |π , π , β¦ , π ; the one-step transition from
π to π π , β¦ , π has been completed, where π is a one-time accomplishment of a Markov chain.
Step 5. Go to Step2.
After t iterationsοΌΞΈ ΞΈ , β¦ , ΞΈ can be obtained. Each component of ΞΈ can also be obtained. Starting from different ΞΈ , as t β β, the marginal distribution of ΞΈ can be viewed as a stationary distribution based on the theory of the ergodic average. Then, the chain is seen as converging, and the sampling points are seen as observations of the sample.
3.2BayesianWeibullmodelforTTF
Suppose the Time to Failure (TTF) data t t , t , β― , t for n individuals are i. i. d., and each corresponds to a 2-parameter Weibull distribution W Ξ±, Ξ³ , where Ξ± 0 and Ξ³ 0. Then, the p. d. f. is f t |Ξ±, Ξ³ Ξ±Ξ³t exp Ξ³t , while the c. d. f. is F t |Ξ±, Ξ³ 1 exp Ξ³t . The reliability function is R t |Ξ±, Ξ³ exp Ξ³t .
Denote the observed data set as D n, t . Therefore, the likelihood function for Ξ± and Ξ³ is
πΏ πΌ, πΎ|π· π π‘ |πΌ, πΎ πΌπΎπ‘ ππ₯π πΎπ‘ 3
6
In this study, we assume Ξ± to be a gamma distribution (Kuo, 1985), denoted by G a , b as its prior distribution, written as Ο Ξ± |a , b ; we assume Ξ³ to be a gamma distribution denoted by G c , d as its prior distribution, written as Ο Ξ³|c , d . This means
π πΌ |π , π β πΌ ππ₯π π πΌ (4)
π πΎ|π , π β πΎ ππ₯π π πΎ (5)
Therefore, the joint posterior distribution can be obtained according to equations (3) to (5) as
π πΌ, πΎ|π· β πΏ πΌ, πΎ|π· π πΌ |π , π π πΎ|π , π , 6
and the parametersβ full conditional distribution with Gibbs sampling can be written as
π πΌπ|πΌ π , πΎ, π·0 β πΏ πΌ, πΎ|π·0 πΌπ0 1ππ₯π π0πΌ 7
π πΎπ|πΌ, πΎ π , π·0 β πΏ πΌ, πΎ|π·0 πΎπ0 1ππ₯π π0πΎ 8
3.3BayesianLognormalmodelforTTR
Suppose the Time to Repair (TTF) data t t , t , β― , t for n individuals are i. i. d., and each ln t corresponds to a normal distribution, N ΞΌ, Ο . We can get t βs lognormal distribution with parameters ΞΌ and Ο . Then, the p. d. f. and c. d. f. are given by equation (9) and equation (10):
π π‘ |π, π1
β2πππ‘ππ₯π
12π
ππ π‘ π 9
πΉ π‘ |π, π Ξ¦ππ π‘ π
π 10
Denote the observed data set as D n, t . Therefore, according to equation (9), the likelihood function for ΞΌ and Ο becomes
πΏ π, π|π· π π‘ |π, π 11
In this study, we assume ΞΌ to be a normal distribution denoted by N e , f as its prior distribution, written as Ο ΞΌ|e , f ; we assume Ο to be a gamma distribution denoted by G g , h as its prior distribution, written as Ο Ο|g , h . This means
π π|π , π β π ππ₯ππ2
π π 12
7
π π|π , β β π ππ₯π β π (13)
Therefore, the joint posterior distribution can be obtained according to equations (11) to (13) as
π π, π|π· β πΏ π, π|π· π π |π , π π π|π , β 14
Then, the parametersβ full conditional distribution with Gibbs sampling can be written as
Ο π |π , π, π· β πΏ π, π|π· π0
12ππ₯π
π0
2π π0
2 15
Ο π |π, π , π· β πΏ π, π|π· π ππ₯π β π 16
4. Casestudy
This section presents a case study; it explains the procedure, gives the results, and offers a discussion.
4.1Theprocedure
The procedure applied in this case study to assess the system availability of the mineβs five balling drums has a total of seven steps, as described in Table 2.
Table 2. Steps in the system availability assessment
Steps Name Purpose Outputsinthiscase
1 Configuration definition
System configuration and dependencies determined to calculate system availability.
Five balling drum system parallel and independent (see Section 2.1).
2 Data collection Reliability and maintenance data (and information) collected.
1774 records for failure and repair data of the five balling drums collected from 2013 to 2018 (see Section 2.2).
3 Data preparation Data cleaned and outliers removed as needed.
Null values removed and abnormal data checked (see Section 2.2).
4 Preliminary Analysis
Pre-studies for TTF and TTR data performed to decide the baseline distributions.
MTTF fits a Weibull distribution; MTTR fits a lognormal distribution (see Section 2.2).
5 Parametric Bayesian model building
Prior distribution defined, and analytic models developed.
Bayesian Weibull model for MTTF with gamma priors and Bayesian lognormal model with gamma and normal priors constructed (see Section 3)
6 MCMC simulation
Burn-in defined and MCMC simulation implemented; convergence diagnostics and Monte Carlo error checked to confirm the effectiveness of the results.
Burn-in of 1000 samples used with an additional 10,000 Gibbs samples for each Markov chain (see Sections 3 and 4.2).
7 Results and analysis
Results, calculation, and discussion.
Results for parameters of interest in system availability assessment (see Sections 4.2 and 4.3).
8
4.2Results
In this case study, the calculations are implemented with WINBUGS. A three-chain Markov chain is constructed for each MCMC simulation. A burn-in of 1000 samples is used, with an additional 10,000 Gibbs samples for each Markov chain.
Vague prior distributions are adopted as follows:
For Bayesian Weibull model using TTF data:
πΌ~πΊ 0.0001, 0.0001 , πΎ~πΊ 0.0001, 0.0001 ;
For Bayesian lognormal model using TTR data:
π~π 0, 0.0001 , π~πΊ 0.0001, 0.0001 .
Using the convergence diagnostics (i.e. checking dynamic traces in Markov chains, determining time series and Gelman-Rubin-Brooks (GRB) statistics, and comparing Monte Carlo error (MC error) with standard deviation (SD)) (Lin, 2014), we consider the following posterior distribution summaries for our models (see Table 3 and Table 4), including the parametersβ posterior distribution mean, SD, MC error, and 95% highest posterior distribution density (HPD) interval.
Table.3 Posterior statistics in Bayesian Weibull model for TTF
Ballingdrum Parameter Mean SD MCerror 95%HPDinterval
1 πΌ 0.5409 0.0231 4.288E-4 (0.4964, 0.5867) πΎ 0.0928 0.0120 2.235E-4 (0.0712, 0.1178)
2 πΌ 0.5747 0.0288 6.289E-4 (0.5195, 0.6324) πΎ 0.0642 0.0109 2.334E-4 (0.0451, 0.0876)
3 πΌ 0.5975 0.0251 5.004E-4 (0.5974, 0.6481) πΎ 0.0712 0.0098 1.942E-4 (0.0707, 0.0922)
4 πΌ 0.5745 0.0245 4.885E-4 (0.5272, 0.6236) πΎ 0.0750 0.0104 2.028E-4 (0.0564, 0.0970)
5 πΌ 0.5560 0.0216 4.135E-4 (0.5558, 0.5988) πΎ 0.0958 0.0112 2.158E-4 (0.0952, 0.1196)
Table.4 Posterior statistics in Bayesian lognormal model for TTR
Ballingdrum Parameter Mean SD MCerror 95%HPDinterval
1 π -0.1842 0.1107 6.730E-4 (-0.4015, 0.0342)
π 0.2270 0.0169 9.565E-5 ( 0.1951,0.2615 )
2 π -0.0075 0.1424 8.504E-4 (-0.2845,0.2697)
π 0.1861 0.0161 9.140E-5 ( 0.1556, 0.2193)
3 π -0.4574 0.1134 6.540E-4 (-0.4578, -0.2354)
π 0.2196 0.0164 9.621E-5 ( 0.2191, 0.2533 )
4 π -0.3540 0.1145 7.052E-4 (-0.5787, -0.1297)
π 0.2184 0.0166 9.845E-5 ( 0.1871, 0.2523 )
5 π -0.3484 0.1023 6.265E-4 (-0.3486, -0.1488)
π 0.2195 0.0148 8.614E-5 ( 0.2189, 0.2495 )
9
Using the results from Table 3 and Table 4, we calculate the availability of individual balling drums in Table 5, where MTTF = E f t |Ξ±, Ξ³ , and MTTR = E f t |ΞΌ, Ο .
Table.5 Statistics of individual availability
BallingdrumMTTF MTTR Availability
Mean 95% HPD interval Mean 95% HPD interval Mean 95% HPD interval 1 145.0 (118.1, 178.0) 7.779 (5.284, 11.58) 0.9487 (0.9229, 0.9665) 2 196.4 (157.7, 256.0) 15.48 (8.927, 26.60) 0.9265 (0.8766, 0.9582) 3 128.7 (127.9, 155.0) 6.381 (6.194, 9.622) 0.9525 (0.9538, 0.9693) 4 148.5 (122.5, 180.3) 7.178 (4.755, 10.86) 0.9536 (0.9291, 0.9702) 5 115.8 (115.1, 139.0) 7.083 (6.926, 10.22) 0.9420 (0.9433, 0.9610)
According to equation (2), the system availability of the five balling drums is
π΄ 1 1 π΄ 0.99
4.3Discussion
Compared to the traditional method of assessing availability in equation (1), the proposed approach extends the method to equation (17), where
π΄πΈ π πππΉ
πΈ π πππΉ πΈ π πππ
πΈ π π‘ |πΌ, πΎπΈ π π‘ |πΌ, πΎ πΈ π π‘ |π, π .
17
Equation (17) shows the flexibility of assessing availability according to reality. For one thing, the parametric Bayesian models using MCMC make the calculation of posteriors more feasible. More importantly, however, parametric Bayesian models can be applied to predict TTF, TTR, and system availability in the future.
In this study, since the five balling drums are relatively new, the gamma distributions and normal distributions are selected as vague priors due to lack of prior information. This could be improved with more historical data/experience.
The system configurations could be extended to other more complex architectures (series, k-out-of-n, stand-by, multi-state, or mixed) by modifying equation (2).
The data analysis reveals that for TTF data, the shape parameter for the Weibull distribution is less than 1. The TTFs have a decreasing trend (as in an early stage of the bathtub curve) which is not suitable for the experience of mechanical equipment. The TTF data include not only corrective maintenance but also preventive maintenance. In this case study, a high percentage of TTF work orders are for preventive maintenance. The decreasing trends also indicate that a possible way to improve TTF is to improve the preventive maintenance plan.
Among those three stages, Step 1 to Step 4 can be treated as Plan stage; Step 5 and Step 6 as Do and Check stage, while Step 7 as Action stage. The outputs from Step 7 could become input for
10
Step 2 for the next calculation period. It means these eight steps are following the βPDCAβ cycle and the results could be continuously improved.
5. Conclusions
This study proposes a parametric Bayesian approach for system availability assessment on the operational stage. MCMC is adopted to take advantages of the analytical and simulation methods.
In this approach, MTTF and MTTR are treated as distributions instead of being βaveragedβ by a point estimation. This better reflects the reality; in addition, the limitations of simulation data sample size are compensated for by MCMC techniques.
In the case study, TTF and TTR are determined using a Bayesian Weibull model and a Bayesian lognormal model. The results show that the proposed approach can integrate the analytical and simulation methods for system availability assessment and could be applied to other technical problems in asset management (e.g., other industries, other systems).
Acknowledgements
The motivation for the research originated from the project βKey Performance Indicators (KPI) for control and management of maintenance process through eMaintenance (In Swedish: Nyckeltal fΓΆr styrning och uppfΓΆljning av underhΓ₯llsverksamhet m h a eUnderhΓ₯ll)β, which was initiated and financed by LKAB. The authors wish to thank Ramin Karim, Peter Olofsson, Mats Renfors, Sylvia Simma, Maria Rytty, Mikael From and Johan Enbak, for their support for this research in the form of funding and work hours.
References
Brender, D. M., 1968. The Bayesian Assessment of System Availability: Advanced Applications and Techniques. IEEEtransactionsonReliability,17(3), pp. 138-147.
Brender, D. M., 1968. The Prediction and Measurement of System Availability: A Bayesian Treatment. IEEETransactionsonReliability,17(3), pp. 127-138.
Dekker, R. & Groenendijk, W., 1995. Availability Assessment Methods and their Application in Practice. MicroelectronicsReliability,35(9-10), pp. 1257-1274.
Faghih-Roohi, S., Xie, M., Ng, K. M. & Yam, R. C., 2014. Dynamic Availability Assessment and Optimal Component Design of Multi-state Weighted k-out-of-n Systems. ReliabilityEngineeringandSystemSafety,Volume 123, pp. 57-62.
Khan, M. A. & Islam, H., 2012. Bayesian Analysis of System Availability with Half-Normal Life Time. QualityTechnologyandQuantitativeManagement,9(2), pp. 203-209.
Kuo, W., 1985. Bayesian Availability Using Gamma Distributed Priors. IIETransactions,17(2), pp. 132-140.
11
Lin, J., 2014. An Integrated Procedure for Bayesian Reliability Inference using Markov Chain Monte Carlo Methods. JournalofQualityandReliabilityEngineering,Volume 2014, pp. 1-16.
Marquez, A. C., Heguedas, A. S. & Iung, B., 2005. Monte Carlo-based Assessment of System Availability. A Case Study for Cogeneration Plants. ReliabilityEngineeringandSystemSafety,Volume 88, pp. 273-289.
Marquez, A. C. & Iung, B., 2007. A Structured Approach for the Assessment of System Availability and Reliablity using Monte Carlo Simulatoin. JournalofQualityinMaintenanceEngineering,13(2), pp. 125-136.
Ocnasu, A. B., 2007. Distribution System Availability Assessment βMonte Carlo and Antithetic VariatesMethod.Vienna, 19th International Conference on Electricity Distribution.
Raje, D., Olaniya, R., Wakhare, P. & Deshpande, A., 2000. Availability Assessment of a Two-unit Stand-by Pumping System. ReliabilityEngineeringandSystemSafety,Volume 68, pp. 269-274.
Sharma, K. & Bhutani, R., 1993. Bayesian Analysis of System Availability. MicroelectronicReliability,33(6), pp. 809-811.
Yasseri, S. F. & Bahai, H., 2018. Availability Assessment of Subsea Distribution Systems at the Architectural Level. OceanEngineering,Volume 153, pp. 399-411.
Zio, E., Marella, M. & podofillini, L., 2007. A Monte Carlo Simulation Approach to the Availability Assessment of Multi-state System with Operational Dependencies. Reliability Engineering and SystemSafety,Volume 92, pp. 871-882.
PaperC
A novel Bayesian approach to system availability assessment using a threshold to censor data
Saari, E., Lin, J., Liu B, Zhang, L-W and Karim, R.. 2019. A novel Bayesian approach to system availability assessment using a threshold to censor data. InternationalJournalofPerformabilityEngineering.Published.
1
AnovelBayesianapproachtosystemavailabilityassessmentusingathresholdtocensordata
A case study of balling drums in a mining company
Esi Saari1, Jing Lin1*, Bin Liu2, Liangwei Zhang1,3, Ramin Karim1
1. DivisionofOperationandMaintenanceEngineering,LuleΓ₯UniversityofTechnology,LuleΓ₯,Sweden;2. DepartmentofManagementScience,UniversityofStrathclyde,Glasgow,UK;3. DepartmentofIndustrialEngineering,DongguanUniversityofTechnology,Dongguan,China.
*Correspondingauthor;Eβmailaddress:[email protected]
Abstract:Assessment of system availability has been studied from the design stage to the operational stage in various system configurations using either analytic or simulation techniques. However, the former cannot handle complicated state changes and the latter is computationally expensive. This study proposes a Bayesian approach to evaluate system availability. In this approach: 1) Mean Time to Failure (MTTF) and Mean Time to Repair (MTTR) are treated as distributions instead of being βaveragedβ to better describe real scenarios and overcome the limitations of data sample size; 2) Markov Chain Monte Carlo (MCMC) simulations are applied to take advantages of the analytical and simulation methods; 3) a threshold is set up for Time to Failure (TTR) data and Time to Repair (TTR) data, and new datasets with right-censored data are created to reveal the connections between technical and βSoftβ KPIs. To demonstrate the approach, the paper considers a case study of a balling drum system in a mining company. In this system, MTTF and MTTR are determined by a Bayesian Weibull model and a Bayesian lognormal model respectively. The results show that the proposed approach can integrate the analytical and simulation methods to assess system availability and could be applied to other technical problems in asset management (e.g., other industries, other systems). By comparing the results with and without considering the threshold for censoring data, we show the threshold can be used as a monitoring line for continuous improvement in the investigated mining company.
Keywords: System availability, Bayesian statistics, Gibbs sampling, Kaplan-Meier estimation, mining industry.
1. Introduction
Availability, commonly measured as Mean Time to Failure (MTTF) and Mean Time to Repair (MTTR), is one of the most critical aspects of performance evaluation. Approaches to assessing system availability mainly use either analytic or simulation techniques (note: PC tools and databases are other options, but are not part of this research).
Simulation techniques estimate availability by simulating the actual process and random behaviour of the system. The advantage is that non-Markov failures and repair processes can be modelled easily (Raje, et al., 2000) (Marquez, et al., 2005) (Marquez & Iung, 2007) (Yasseri & Bahai, 2018), as can multi-state systems with operational dependencies (Zio, et al., 2007). Although simulation is more flexible, it is computationally expensive. In general, analytic techniques represent the system using mathematical solutions from applied probability theory to make
2
statements on various performance measures (Dekker & Groenendijk, 1995) (Ocnasu, 2007) (Marquez, et al., 2005). (Faghih-Roohi, et al., 2014). However, such approaches have been criticised as too restrictive to tackle practical problems; they assume constant failure and repair rates, and this is not likely to be the case in the real world. Furthermore, the time dependent availability obtained by a Markovian assumption (a common analytic technique) is actually not valid for non-Markovian processes (Raje, et al., 2000). Traditionally, Bayesian statistical approaches have been used to assess system availability as they can solve the problem of complicated system state changes and computationally expensive simulation data, but they require strict assumptions on prior forms and can be computationally difficult. Bayesian research is more concerned with the priorβs selection or the posteriorβs computation than the reality (Brender, 1968) (Brender, 1968) (Kuo, 1985) (Sharma & Bhutani, 1993) (Khan & Islam, 2012).
This study proposes a novel Bayesian approach to system availability assessment, combining analytic and simulation techniques. In the proposed approach: 1) Mean Time to Failure (MTTF) and Mean Time to Repair (MTTR) are treated as distributions instead of being βaveragedβ to better reflect reality and compensate for the limitations of simulation data sample size; 2) Markov Chain Monte Carlo (MCMC) simulations are used to take advantage of both analytical and simulation methods (Lin, 2014); 3) a threshold is established for Time to Failure (TTF) data and Time to Repair (TTR) data; new datasets created with right-censored data reveal the connections between technical and βsoftβ KPIs.
The rest of this paper is organized as follows. Section 2 explains the three stages of the proposed Bayesian approach. Section 3 describes Stage I, pre-analysis, including the configuration of a balling drum system in a case study mine, data collection and preparation, and the preliminary analysis of failure and repair data. Section 4 presents Stage II; it proposes a Bayesian Weibull model for MTTF and a Bayesian lognormal model for MTTR considering right-censored data and explains how to use an MCMC computational scheme to obtain the posterior distributions. Section 5 explains Stage III, the assessment of system availability. Section 6 presents and assess the results of a case study and then compares results with and without considering the data censored by the threshold. Section 7 features a discussion, while Section 8 provides conclusions and makes suggestions for further study.
2. Ageneralprocedure
The proposed Bayesian approach to system availability has seven steps divided into three stages (see Table 1): 1) in Stage I, we perform pre-analysis; 2) in Stage II, we create the analytic models (Bayesian) and simulation models (MCMC); 3) in Stage III, we assess system availability.
The seven steps follow a βPDCAβ cycle; those in Stage I can be treated as the Plan stage, Stage II as the Do and Check stage, and Stage III as the Action stage. The outputs from Stage III could become input for Stage I for the next calculation period, so the results can be continuously improved.
To accomplish step 2, prior information can come from: 1) engineering design data; 2) component test data; 3) system test data; 4) operational data from similar systems; 5) field data in various environments; 6) computer simulations; 7) related standards and operation manuals; 8)
3
experience data from similar systems; 9) expert judgment and personal experience. Of these, the first seven yield objective prior data, and the last two provide subjective prior data. Prior data also take a variety of forms, including reliability data, the distribution of reliability parameters, moments, confidence intervals, quantiles, upper and lower limits, etc. (Lin, 2014).
In step 3, a threshold is set up according to the asset management goals connected with the organizationβs business goals (see later sections for a more detailed discussion). In step 4, various types of priors can be used because of the flexibility of MCMC. In this study, since the balling drums in the case study mine are quite new, we adopt vague priors. In step 5, the likelihood function can differ according to the types of censored/ truncated data, while the Bayesian analytics could differ according to the preliminary study of the baseline analysis of TTF and TTR. In step 6, checking the MCMC simulation can follow Lin (2014). In step 7, system availability can also be described by an empirical distribution instead of an analytical one.
Table 1. A general procedure
Stages Steps Name Description
I
1 Configuration determination
Determine dependencies among units and system configuration.
2 Data collection Collect prior information and event data, including reliability and maintenance data.
3 Data preparation Clean data and remove outliers as needed. Set up a threshold for censored data.
4 Preliminary Analysis
Determine the distribution of prior information, TTF, and TTR for the Bayesian analytics in step 5.
II
5 Bayesian analytic modelling
According to step 3 and step 4, determine the likelihood function and Bayesian analytic models.
6 MCMC simulation
Define burn-in defined and implement MCMC simulation; perform convergence diagnostics and check Monte Carlo error to confirm the effectiveness of the results. If not passed, go back to step 4 and 5; if passed, go to step 7.
III 7 Assessment
According to the simulation results for Bayesian analytic models and system configuration, determine distributions of TTF and TTR and assess system availability. Assessment could start with the prior information collection in step 2 for the next calculation period.
3. StageI:Preβanalysis
3.1Configurationofballingdrumsystem
The case study mine has five balling drums, labelled 1-5. All five balling drums receive their feed for production in the same manner, and each balling drum is expected to produce the same amount of pellets at its maximum. According to the company, the balling drums are independent; if one breaks down, it does not affect the rest. One assumption is made here that the system will fail only if all subsystems fail; therefore, it is treated as a parallel system (Figure 1).
4
Figure1 Description of a balling drum and the system sketch
The availability of a single balling drum, denoted as π΄ , can be computed by
π΄ππππΉ
ππππΉ ππππ 1
The total system availability for this parallel configuration, π΄ , can be calculated as
π΄ 1 1 π΄ 2
3.2Datacollectionanddatapreparation
The study uses the failure and repair data of the five balling drums from January 2013 to December 2018. There are 1782 records. In the first step of data preparation, the null values are removed, and the data are reduced to 1774 records.
In the next step, we look for the normal and abnormal values for the TTF and TTR of individual balling drums. If 150 shutdowns are considered normal, for example, then those exceeding 150 are abnormal, and 150 is denoted as a threshold, as shown in Figure 2. The work orders show most of these abnormal shutdowns are caused by βpreventive maintenanceβ and may simply reflect a lack of maintenance resources. To simplify the study, we assume that not all maintenance resources are sufficient for βpreventive maintenanceβ; thus, the abnormal data may reflect a shortage of spare parts or skilled personnel.
5
Figure2 Example of TTR data for balling drum 1
To establish a more reasonable TTR threshold than the 150 shutdowns, we perform a Pareto analysis for all balling drums. The results shown in Figure 3. According to the figure, if the threshold is set up according to the β80-20β rule, the data can be censored at six hours. This explains almost 80% of the data. Therefore, we create a new dataset with TTR censored at six hours.
Figure3 Pareto analysis for TTR of five balling drums
In addition, we make the following assumptions:
1. Abnormal TTR values exceeding six hours could be improved by implementing maintenance improvements, including Root Cause Analysis (RCA), maintenance resource improvement, etc. The goal is to reduce the TTR values exceeding six hours. However, we
6
donβt know how much we can do. Therefore, those values are considered right censored at six;
2. The preventive maintenance plan is not changed. Thus, if one TTR is treated as censored, then in the corresponding maintenance interval, the Time between Failure (TBF), which equals to TTF plus TTR, will not change significantly, and the TTF could be longer than in the collected data. However, we donβt know how much longer the TTF could be. Therefore, TTF data can also be treated as right censored. The difference with censored TTR data is that the corresponding TTF data are treated as right-censored at the original value instead of a new value (see Figure 4).
Figure 4 Data censored under assumptions
We use Figure 4 to illustrate assumption 2. TBF equals to the time between t and t . TTR =t - t might be larger than six but it is right censored at six. Then, the original TTR is denoted as six with a right-censored indicator. Since TBF= t - t will not change, the corresponding TTFβ= π‘ t will be longer than TTF. However, according to assumption 2, we donβt know how much longer; therefore, TTFβ is denoted as right-censored data with an original value equal to t - t .
After this step, the censored TTF and TTR data represent a total of 20% of all data.
3.3Preliminaryanalysis
To determine the baseline distribution of TTR and TTF, we conduct a preliminary study of failure data and repair data using traditional analysis. We consider the following distributions: exponential distribution, Weibull distribution, normal distribution, log-logistic distribution, lognormal distribution, and extreme value distribution. Table 2 lists the results, including the goodness-of-fit using Anderson-Darling (AD) statistics.
Table 2 Preliminary study of failure data and repair data
Ballingdrum
TTFfitness TTRfitness1st AD 2nd AD 1st AD 2nd AD
1 Weibull 1.976 Lognormal 11.276 Lognormal 10.068 Weibull 14.607 2 Weibull 1.796 Lognormal 8.274 Lognormal 11.144 Weibull 14.302 3 Weibull 2.115 Lognormal 10.499 Lognormal 8.698 Weibull 14.332 4 Weibull 1.196 Lognormal 6.366 Lognormal 9.245 Weibull 13.106 5 Weibull 2.148 Lognormal 14.416 Lognormal 7.533 Weibull 11.933
7
Based on the results, we select the Weibull distribution for the TTF and the lognormal distribution for the TTR and apply these to their respective parametric Bayesian models with censored data, as explained in the next section.
4. StageII:Analyticandsimulationmodels
This section elaborates on the analytic and simulation models described in Stage II. It proposes a Bayesian Weibull model for TTF and a Bayesian lognormal model for TTR and explains how to use an MCMC computational scheme to obtain the posterior distributions considering right-censored data.
4.1MarkovChainMonteCarlowithGibbssampling
The recent proliferation of Markov Chain Monte Carlo (MCMC) approaches has led to the use of the Bayesian inference in a wide variety of fields. MCMC is essentially Monte Carlo integration using Markov chains. Monte Carlo integration draws samples from the required distribution and then forms sample averages to approximate expected results. MCMC draws out these samples by running a cleverly constructed Markov chain for a long time. There are many ways of constructing these chains. The Gibbs sampler is one of the best known MCMC sampling algorithms in the Bayesian computational literature. In this method, when a set of parameters must be evaluated, the other parameters are assumed to be fixed and known. Let π be an π-dimensional vector of parameters, and let π π denote the marginal distribution for the π th parameter. The basic scheme of the Gibbs sampler for sampling from π π comprises the following steps:
Step 1. Choose an arbitrary starting point π π , β¦ , π ; Step 2. Generate π from the conditional distribution π π |π , β¦ , π , and
generate π from the conditional distribution π π |π , π , β¦ , π ; Step 3. Generate π from π π |π , β¦ , π , π β¦ , π ; Step 4. Generate π from π π |π , π , β¦ , π ; the one-step transition from
π to π π , β¦ , π has been now completed, where π is a one-time accomplishment of a Markov chain.
Step 5. Go to Step2.
After π‘ iterationsοΌπ π , β¦ , π can be obtained. Each component of π can also be obtained. Starting from different π , as π‘ β β, the marginal distribution of π can be viewed as a stationary distribution based on the theory of the ergodic average. The chain is seen as converging, and the sampling points are seen as observations of the sample.
4.2Likelihoodconstructionforrightβcensoreddata
In practice, lifetime data are usually incomplete, and only a portion of the individual lifetimes of assets are known. Right-censored data are often called Type I censoring in the literature; the corresponding likelihood construction problem has been extensively studied. The right-censored data of this study are illustrated in Figure 4.
Suppose there are π individuals whose lifetimes and censoring times are independent. The π th individual has life time π and censoring time πΏ . The π s are assumed to have probability density
8
function π π‘ and reliability function π π‘ . The exact lifetime π of an individual will be observed only if π πΏ . The lifetime data involving right censoring can be conveniently represented by π pairs of random variables π‘ , π£ , where π‘ min π , πΏ and π£ 1 if π πΏ and π£ 0if π πΏ . That is, π£ indicates whether the lifetime π is censored or not. The likelihood function is deduced as
πΏ π‘ π π‘ π π‘ 3
4.3BayesianmodellingforTTF
Suppose the Time to Failure (TTF) data π‘ π‘ , π‘ , β― , π‘ for π individuals are π. π. π., and each corresponds to a 2-parameter Weibull distribution π πΌ, πΎ , where πΌ 0 and πΎ 0. Then, the π. π. π. is π π‘ |πΌ, πΎ πΌπΎπ‘ ππ₯π πΎπ‘ , while the π. π. π. is πΉ π‘ |πΌ, πΎ 1 ππ₯π πΎπ‘ , and the reliability function is π π‘ |πΌ, πΎ ππ₯π πΎπ‘ .
Let π£ π£ , π£ , β¦ , π£ indicate whether the lifetime is right-censored or not, and let the observed dataset for the study be denoted as π· , where π· π, π‘, π£ , following equation (3). Therefore, the likelihood function for πΌ and πΎ is
πΏ πΌ, πΎ|π· πΌβ ππ₯π π£ ππ πΎ π£ πΌ 1 ππ π‘ πΎπ‘ 4
In this study, we take Ξ± and πΎ to be independent. Furthermore, we assume Ξ± to be a gamma distribution, denoted by πΊ π , π as its prior distribution, written as Ο πΌ |π , π , and we assume πΎ to be a gamma distribution denoted by πΊ π , π as its prior distribution, written as Ο πΎ|π , π . This means
π πΌ |π , π β πΌ ππ₯π π πΌ (5)
π πΎ|π , π β πΎ ππ₯π π πΎ (6)
Therefore, the joint posterior distribution can be obtained according to equations (4) to (6) as
π πΌ, πΎ|π· β πΏ πΌ, πΎ|π· π πΌ |π , π π πΎ|π , π 7
The parametersβ full conditional distribution with Gibbs sampling can be written as
π πΌπ|πΌ π , πΎ, π·0 β πΏ πΌ, πΎ|π·0 πΌπ0 1ππ₯π π0πΌ 8
π πΎπ|πΌ, πΎ π , π·0 β πΏ πΌ, πΎ|π·0 πΎπ0 1ππ₯π π0πΎ 9
9
4.4BayesianmodellingforTTR
Suppose the Time to Repair (TTR) data π‘ π‘ , π‘ , β― , π‘ for π individuals are π. π. π., and each ππ π‘ corresponds to a normal distribution π π, π . We can get π‘ βs lognormal distribution with parameters π and π , denoted by πΏπ π, π . Then, the π. π. π. and π. π. π. are given by equation (10) and equation (11):
π π‘ |π, π1
β2πππ‘ππ₯π
12π
ππ π‘ π 10
πΉ π‘ |π, π Ξ¦ππ π‘ π
π 11
The likelihood function related to π and π , considering the censoring indicators π£π£ , π£ , β¦ , π£ and the observed data set π· π, π‘, π£ , becomes
πΏ π, π|π· 2ππ β ππ₯π1
2πππ π‘ π π‘ 1 Ξ¦
ππ π‘ ππ
12
In this study, we assume π to be a normal distribution denoted by π π , π as its prior distribution, written as π π|π , π , and we assume π to be a gamma distribution denoted by πΊ π , β as its prior distribution, written as π π|π , β . This means
π π|π , π β π ππ₯ππ2
π π 13
π π|π , β β π ππ₯π β π (14)
Therefore, the joint posterior distribution can be obtained according to equations (12) to (14) as
π π, π|π· β πΏ π, π|π· π π |π , π π π|π , β 15
The parametersβ full conditional distribution with Gibbs sampling can be written as
Ο π |π , π, π· β πΏ π, π|π· π0
12ππ₯π
π0
2π π0
2 16
Ο π |π, π , π· β πΏ π, π|π· π ππ₯π β π 17
5. StageIII:Assessment
According to the results from Stage II, the distribution for TTF and TTR can be achieved separately for balling drums 1 to 5. Compared to the traditional method of assessing availability in equation (1), the proposed approach extends the method to equation (18), where
10
π΄πΈ π πππΉ
πΈ π πππΉ πΈ π πππ
πΈ π π‘ |πΌ, πΎπΈ π π‘ |πΌ, πΎ πΈ π π‘ |π, π .
18
Equation (18) shows the flexibility of assessing availability according to reality. For one thing, the parametric Bayesian models using MCMC make the calculation of posteriors more feasible.
Based on the system configuration determined in Stage I, and using the results from Stage II for π πΌ, πΎ , πΏπ π, π and equation (18), TTF, TTR, and system availability can be assessed.
System availability can be computed via the TTF and TTR. However, according to equation (18), we cannot obtain a closed-form distribution of system availability. Therefore, we use an empirical distribution instead of an analytical one. As illustrated in the case study, the Kaplan-Meier estimate can be used as the empirical π. π. π.
6. Casestudy
In this case study of five balling drums, the Markov chain is constructed for each MCMC simulation. A burn-in of 1000 samples is used, with an additional 10,000 Gibbs samples for each Markov chain.
Vague prior distributions are adopted as follows:
For the Bayesian Weibull model using TTF data:
πΌ~πΊ 0.0001, 0.0001 , πΎ~πΊ 0.0001, 0.0001 ;
For the Bayesian lognormal model using TTR data:
π~π 0, 0.0001 , π~πΊ 0.0001, 0.0001 .
6.1Results
Table 3 Posterior statistics in Bayesian Weibull model with censored TTF data
Ballingdrum Parameter Mean SD MCerror 95%HPDinterval
1 πΌ 0.5399 0.0235 4.34E-4 (0.4954, 0.5870) πΎ 0.0934 0.0122 2.26E-4 (0.0710, 0.1186)
2 πΌ 0.5721 0.0289 6.25E-4 (0.5159, 0.6295) πΎ 0.0651 0.0110 2.39E-4 (0.0459, 0.0890)
3 πΌ 0.5781 0.0251 5.08E-4 (0.5299, 0.6281) πΎ 0.0742 0.0104 2.09E-4 (0.0555, 0.0961)
4 πΌ 0.5713 0.0252 5.14E-4 (0.5228, 0.6210) πΎ 0.0763 0.0109 2.22E-4 (0.0569, 0.0992)
5 πΌ 0.5601 0.0219 3.95E-4 (0.5176, 0.6038) πΎ 0.0940 0.0111 1.99E-4 (0.0735, 0.1175)
11
Using convergence diagnostics (i.e. checking dynamic traces in Markov chains, determining time series and Gelman-Rubin-Brooks (GRB) statistics, and comparing MC error with standard deviation (SD)) (Lin, 2014), we consider the posterior distribution statistics shown in Table 3 and Table 4, including the parametersβ posterior distribution mean, SD, Monte Carlo error (MC error), and 95% highest posterior distribution density (HPD) interval.
Table 4 Posterior statistics in Bayesian lognormal model with censored TTR data
Ballingdrum Parameter Mean SD MCerror 95%HPDinterval
1 π -0.4501 0.0882 4.98E-4 (-0.6250, -0.2776)
π 0.3585 0.0267 1.50E-4 (0.3078, 0.4125)
2 π -0.3825 0.1082 6.24E-4 (-0.5959, -0.1719)
π 0.3277 0.0285 1.56E-4 (0.2742, 0.3853)
3 π -0.4510 0.0839 5.10E-4 (-0.6176, -0.2871)
π 0.4041 0.0305 1.80E-4 (0.3463, 0.4660)
4 π -0.6124 0.0907 5.29E-4 (-0.7924, -0.4351)
π 0.3516 0.0266 1.49E-4 (0.3010, 0.4057)
5 π -0.6023 0.0812 4.72E-4 (-0.7633, -0.4432)
π 0.3524 0.0238 1.39E-4 (0.3072, 0.4007)
6.2Assessment
Using the results from Table 3 and Table 4 for balling drums 1 to 5, we derive the distributions of TTF and TTR as shown in Table 5.
Table 5 Statistics of individual balling drums with censored data
Ballingdrum
TTF TTR Availability
π πΌ, πΎ πΏπ π, π 1 1 πΏπ π, π π πΌ, πΎββ
1 π 0.5399, 0.0934 πΏπ 0.4501, 0.3585 1 1 πΏπ π, π π πΌ, πΎββ
2 π 0.5721, 0.0651 πΏπ 0.3825, 0.3277 1 1 πΏπ π, π π πΌ, πΎββ
3 π 0.5781, 0.0742 πΏπ 0.4510, 0.4041 1 1 πΏπ π, π π πΌ, πΎββ 4 π 0.5713, 0.0763 πΏπ 0.6124, 0.3516 1 1 πΏπ π, π π πΌ, πΎββ 5 π 0.5601, 0.0940 πΏπ 0.6023, 0.3524 1 1 πΏπ π, π π πΌ, πΎββ
Using the results in Table 5, we create π. π. π. and π. π. π. charts of TTF and TTR data in Figure 5 and Figure 6.
12
(a) π. π. π. of TTF (b) π. π. π. of TTR
Figure 5 π. π. π. of TTF and TTR
(a) π. π. π. of TTF (b) π. π. π. of TTR
Figure 6 π. π. π. of TTF and TTR
As discussed above, system availability can be computed via the TTF and TTR, but we cannot obtain a closed-form distribution of system availability. Therefore, we use an empirical distribution instead of an analytical one. We generate 10,000 samples from the distributions of TTF and TTF and calculate the associated availability. Figure 7 presents the histogram of availability of the five balling drums. We use the Kaplan-Meier estimate as the empirical π. π. π. Figure 8 shows the empirical distribution of the availability of the five balling drums.
13
Balling drum 1 Balling drum 2
Balling drum 3 Balling drum 4
Balling drum 5
Figure 7 Histogram plot of availability
Figure 8 Empirical π. π. π. of availability
Table 6 Statistics of individual balling drums with censored data
BallingdrumMTTF MTTR Availability
Mean 95% HPD interval Mean 95% HPD interval Mean 95% HPD interval 1 145.0 (118.4, 178.2) 2.616 (2.000, 3.437) 0.9821 (0.9753, 0.9873) 2 197.0 (157.6, 247.5) 3.223 (2.301, 4.540) 0.9837 (0.9759, 0.9893) 3 146.0 (120.7, 177.0) 2.239 (1.741, 2.864) 0.9848 (0.9795, 0.9890) 4 149.0 (122.5, 181.8) 2.289 (1.736, 3.041) 0.9847 (0.9788, 0.9891) 5 115.0 (96.40, 137.5) 2.296 (1.796, 2.958) 0.9803 (0.9736, 0.9855)
14
We calculate the availability of the individual balling drums in Table 6, where MTTF = πΈ π π‘ |πΌ, πΎ , and MTTR = πΈ π π‘ |π, π .
According to equation (2), the system availability of the five balling drums is
π΄ 1 1 π΄ 0.99
7. Discussion
7.1Acomparisonstudy
For comparative purposes, Table 7 and Table 8 show the statistics of the individual balling drums with no censored data. All TTF and TTR data collected in Stage I are treated as reasonable and require no improvement.
Table 7 Statistics of individual balling drums with no censored data
Ballingdrum
TTF TTR Availability
π πΌ, πΎ πΏπ π, π 1 1 πΏπ π, π π πΌ, πΎββ
1 π 0.5409, 0.0928 πΏπ 0.1842, 0.2270 1 1 πΏπ π, π π πΌ, πΎββ
2 π 0.5747, 0.0642 πΏπ 0.0075, 0.1861 1 1 πΏπ π, π π πΌ, πΎββ
3 π 0.5975, 0.0712 πΏπ 0.4574, 0.2196 1 1 πΏπ π, π π πΌ, πΎββ 4 π 0.5745, 0.0750 πΏπ 0.3540, 0.2184 1 1 πΏπ π, π π πΌ, πΎββ 5 π 0.5660, 0.0958 πΏπ 0.3484, 0.2195 1 1 πΏπ π, π π πΌ, πΎββ
Table 8 Statistics of individual balling drums with no censored data
BallingdrumMTTF MTTR Availability
Mean 95% HPD interval Mean 95% HPD interval Mean 95% HPD interval 1 145.0 (118.1, 178.0) 7.779 (5.284, 11.58) 0.9487 (0.9229, 0.9665) 2 196.4 (157.7, 256.0) 15.48 (8.927, 26.60) 0.9265 (0.8766, 0.9582) 3 128.7 (127.9, 155.0) 6.381 (6.194, 9.622) 0.9525 (0.9538, 0.9693) 4 148.5 (122.5, 180.3) 7.178 (4.755, 10.86) 0.9536 (0.9291, 0.9702) 5 115.8 (115.1, 139.0) 7.083 (6.926, 10.22) 0.9420 (0.9433, 0.9610)
For convenience, the results are also listed in Table 9.
Table 9 Comparison of statistics with and without censored data
Ballingdrum
MeanofMTTF MeanofMTTR MeanofAvailabilityNo
censored censored %
No censored
censored % No
censored censored %
1 145.0 145.0 0 7.779 2.616 66.37 0.9487 0.9821 3.52 2 196.4 197.0 0.30 15.48 3.223 79.18 0.9265 0.9837 6.17 3 128.7 146.0 13.4 6.381 2.239 64.91 0.9525 0.9848 3.39 4 148.5 149.0 0.33 7.178 2.289 68.11 0.9536 0.9847 3.26 5 115.8 115.0 0 7.083 2.296 67.58 0.9420 0.9803 4.07
15
In Table 9, β%β denotes the percentage after considering the censored data. For instance, for balling drum 1, after considering the censored data, the mean of MTTF does not change; MTTR improves by 66.37%, and availability improves by 3.52%.
According to the results from Table 9, if 20% of the abnormal TTR data could be improved (for instance, by applying RCA activities, or more specifically, by improving maintenance resource management, including maintenance skills, spare parts, etc.), the TTR could be improved by 66.37%, 79.18%, 64.91%, 68.11%, and 67.58% for drums 1 to 5, respectively. Meanwhile, the availability would be improved by 3.52%, 6.17%, 3.39%, 3.26%, and 4.07% for drums 1 to 5, respectively.
The improvement of the TTF is not as impressive. We apply right-censored data for the TTRs under the assumption that they can be improved (censored at six), but the corresponding TTFs can only be marked as censored instead of censored at some specified value, under the assumption that the maintenance interval will not change all that much. This implies that if the maintenance interval (for instance, the preventive maintenance) could be improved, the TTFs could be improved (censored at a larger value), thus improving the availability.
7.2ConnectionbetweentechnicalandβsoftβKPIs
In the studied company, Key Performance Indicators (KPIs) are divided into two groups: technical KPIs and soft KPIs. The former are related to the performance of equipment, whilst the latter focus on maintenance management.
In this case, the abnormal values of TTR are assumed to be mainly caused by lack of maintenance resources, including personnel with suitable skills, spare parts, etc. KPIs of maintenance resources are treated as βsoftβ KPIs in the company. Therefore, using our comparative approach, we could easily find out how the technical KPIs (TTF, availability of assets) would be influenced by improving βsoftβ KPIs.
7.3Applicationofthethresholdasamonitoringline
In this study, the threshold of abnormal TTR values in the work orders is determined by a β80-20β rule in Pareto analysis, in which a TTR value exceeding six is treated as an abnormally long time for TTR and should be improved by RCA activities, including improving maintenance resource management.
Actually, the threshold could be determined by the company according to its business goals; for instance, they could be set at 70% or 90%, or set according to other rules combined with business goals. The threshold could also be changed gradually to improve the maintenance step by step, following a PDCA process. In another words, the so-called abnormal data are not really abnormal. Finally, the threshold could be treated as a monitoring line, permitting the dynamic monitoring of system availability.
16
7.4Furtherresearch
In this study, since the five balling drums are relatively new, the gamma distributions and normal distributions are selected as vague priors due to lack of real prior information. This could be improved with more historical data/experience.
The system configurations could be extended to other more complex architectures (series, k-out-of-n, stand-by, multi-state, or mixed) by modifying equation (2).
The results of system availability are all larger than 0.99, with or without considering censored data. The difference is not very obvious for two reasons. First, the system configuration is in parallel; second, the individual balling drums have relatively high availabilities (higher than 0.9). The difference (with or without considering censored data) will be more obvious with other system configurations and less individual availability.
For TTF data, the shape parameter for the Weibull distribution is less than 1 (see Figure 5 (a)). The TTFs have a decreasing trend (as in the early stage of the bathtub curve) which is not suitable for the real-world experience of mechanical equipment. However, the TTF data include not only corrective maintenance but also preventive maintenance. The decreasing trends suggest a possible way to improve TTF is to improve the preventive maintenance plan.
8. Conclusions
This study proposes a parametric Bayesian approach to assess system availability in the operational stage. MCMC is adopted to take advantage of both analytical and simulation methods. Because of MCMCβs high dimensional numerical integral calculation, the selection of prior information and descriptions of reliability/maintainability can be more flexible and realistic. In this method, MTTF and MTTR are treated as distributions instead of being βaveragedβ by point estimation. This better reflects reality; in addition, the limitations of simulation data sample size are overcome by MCMC techniques.
In the case study, TTF and TTR are determined using a Bayesian Weibull model and a Bayesian lognormal model, respectively. The results show that:
The proposed approach can integrate analytical and simulation methods for system availability assessment and could be applied to other technical problems in asset management (e.g., other industries, other systems);
There is a connection between technical and βsoftβ KPIs; The threshold can be treated as a monitoring line by the mining company for continuous
improvement.
Acknowledgements
The motivation for the research was the project βKey Performance Indicators (KPIs) for control and management of maintenance process through eMaintenance (In Swedish: Nyckeltal fΓΆr styrning och uppfΓΆljning av underhΓ₯llsverksamhet m h a eUnderhΓ₯ll)β, which was initiated and
17
financed by LKAB. The authors wish to thank Ramin Karim, Peter Olofsson, Mats Renfors, Sylvia Simma, Maria Rytty, Mikael From and Johan Enbak, for their support for this research in the form of funding and work hours.
References
Brender, D. M., 1968. The Bayesian Assessment of System Availability: Advanced Applications and Techniques. IEEEtransactionsonReliability,17(3), pp. 138-147.
Brender, D. M., 1968. The Prediction and Measurement of System Availability: A Bayesian Treatment. IEEETransactionsonReliability,17(3), pp. 127-138.
Dekker, R. & Groenendijk, W., 1995. Availability Assessment Methods and their Application in Practice. MicroelectronicsReliability,35(9-10), pp. 1257-1274.
Faghih-Roohi, S., Xie, M., Ng, K. M. & Yam, R. C., 2014. Dynamic Availability Assessment and Optimal Component Design of Multi-state Weighted k-out-of-n Systems. ReliabilityEngineeringandSystemSafety,Volume 123, pp. 57-62.
Khan, M. A. & Islam, H., 2012. Bayesian Analysis of System Availability with Half-Normal Life Time. QualityTechnologyandQuantitativeManagement,9(2), pp. 203-209.
Kuo, W., 1985. Bayesian Availability Using Gamma Distributed Priors. IIETransactions,17(2), pp. 132-140.
Lin, J., 2014. An Integrated Procedure for Bayesian Reliability Inference using Markov Chain Monte Carlo Methods. JournalofQualityandReliabilityEngineering,Volume 2014, pp. 1-16.
Marquez, A. C., Heguedas, A. S. & Iung, B., 2005. Monte Carlo-based Assessment of System Availability. A Case Study for Cogeneration Plants. ReliabilityEngineeringandSystemSafety,Volume 88, pp. 273-289.
Marquez, A. C. & Iung, B., 2007. A Structured Approach for the Assessment of System Availability and Reliablity using Monte Carlo Simulatoin. JournalofQualityinMaintenanceEngineering,13(2), pp. 125-136.
Ocnasu, A. B., 2007. DistributionSystemAvailabilityAssessmentβMonteCarloandAntitheticVariatesMethod.Conference Proceeding. 19th International Conference on Electricity Distribution. 21st May - 24th May. Vienna, Austria.
Raje, D., Olaniya, R., Wakhare, P. & Deshpande, A., 2000. Availability Assessment of a Two-unit Stand-by Pumping System. ReliabilityEngineeringandSystemSafety,Volume 68, pp. 269-274.
Sharma, K. & Bhutani, R., 1993. Bayesian Analysis of System Availability. MicroelectronicReliability,33(6), pp. 809-811.
Yasseri, S. F. & Bahai, H., 2018. Availability Assessment of Subsea Distribution Systems at the Architectural Level. OceanEngineering,Volume 153, pp. 399-411.
Zio, E., Marella, M. & podofillini, L., 2007. A Monte Carlo Simulation Approach to the Availability Assessment of Multi-state System with Operational Dependencies. ReliabilityEngineeringandSystemSafety,Volume 92, pp. 871-882.