optimization and automation of production process at roop polymers ltd through project management

7/28/2019 Optimization and Automation of Production Process at Roop Polymers Ltd Through Project Management

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OPTIMIZATION AND AUTOMATION OF PRODUCTION

PROCESS AT ROOP POLYMERS LTD THROUGH PROJECT

MANAGEMENT

Thesis submitted in the partial fulfilment of the requirements for the

Award of the Degree of

MASTER OF TECHNOLOGY

IN

(PRODUCTION ENGINEERING)

Under the supervision of: Submitted by:

Dr. A.K.Vij Amit Gulia

Professor of Management studies 11-PEP-004s

Ms. Amrita Jhawar

Department of mechanical engineering


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MECHANICAL ENGINEERING DEPARTMENT

ITMU GURGAON

2011-2013


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CERTIFICATE

i


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ABSTRACT

The following study is conducted on basis of practical study of a construction project of an

company which is required to build a new facility which is required for masters degree in

context to learn and implement the various techniques of the project management. Projectmanagement is about making decisions under uncertainty, throughout the various phases of a

project. According to this study we implement management tools and processes to form a

effective and efficient system. This study examines the relationships among project performance,

customer satisfaction, and project success by assessing the efficacy of management techniques,

tools, and skills for implementing infrastructure and building construction. In this report I have

discussed the various tools and techniques of optimization. They provide step by step study of

every process in rubber manufacturing process. the process steps can be optimized and organized

in such a way that it provides maximum efficiency of the process.

ii


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CONTENT

Description: Page No.

Certificate i

Abstract ii

Contents iii

Gantt Chart v

List of figures vi

Nomenclatures vii

Chapter 1-Introduction

1.1. Objectives of the project

1.2. Success parameters of the project

1.3. Brief Introduction of the project

1.4 Process Optimization Tool1.5. Value Proposition

1.6. Steps of process optimization

1.7 Roop Polymers Pvt Ltd (Company Profile)

Chapter 2- General process of making a rubber component

2.1. Products and Raw materials used

2.2. General Process of manufacturing of rubber component

Chapter 3 -Literature review

3.1. Research papers

3.2. Advanced Manufacturing


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Chapter 4- Production and Manufacturing Process and Support

4.1 Production System Facilities

4.2 Low Quantity Production

4.3 Medium Quantity Production

4.4 High Production

4.5 Manufacturing Support System

Chapter 5- Automation in Production System

5.1 Automation in Production System

5.2 Automated Manufacturing Systems

5.3 Reasons for Automating

5.4 Automation Migration Strategy

5.5 Equipments used for Automation

5.6 Introduction to test automation

5.6.1 Forecasting test automation benefits

5.6.2 Costs of Automation

5.7 Cost of Automation

5.8. Advantages of Automation

Chapter 6- Recommendations and implementation of the corrective measures

6.1. Line or Product layout

6.2. Comparison of both the Manual and Automated Manufacturing Process

6.3 What is ROI?


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6.3.1 Need of test automation using ROI

6.4 Productivity

6.5 Product/ Production Relationship

6.6 Product and Part Complexity

Chapter 7- Business Process Modelling Technique

7.1 Calculate Cost Accruals Event-Driven Process Chain

7.1.1 Function Allocation Diagram

7.2 Documenting Processes

Chapter 8- Conclusion

References

iii


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GANTT CHART

iv


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Figure List:

Figure 1: Process Improvement

Figure 2: Steps of Process Optimization

Figure 3: Bonded flexible chains

Figure 4: Compression Modelling

Figure 5: Injection Modelling

Figure 6: Transfer Modelling

Figure 7: General Process

Figure 8: Major Process of Rubber

Figure 9: Manufacturing Process Behaviour

Figure 10: The production system consists of facilities and manufacturing support systems.

Figure 11: Various types of plant layout

Figure 12: Types of facilities and layouts used for different levels of production quantity and

product variety.

Figure 13: The information processing cycle in a typical manufacturing firm.

Figure 14: Opportunities of automation and computerization in a production system.

Figure 15: Three types of automation relative to production quantity and product variety.

Figure 16: Model of manufacturing showing factory operations and the information processing

activities for manufacturing support.

Figure 17: A typical automation migration strategy

Figure 18: PLC system and Change over System for Intimex

Figure 19: Test Automation

Figure 20: Distributed Test Automation Infrastructure


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Figure 21 (a): Line layout

Figure21 (b): Line Layout

Figure 22: 3-Tier Industrial Network Diagram

Figure 23: Network diagram for automating the current process

Figure 24: Time taken by the manual process

Figure 25: Time taken by individual process

Figure 26: Problem Occurrence in Automated Manufacturing Process

Figure 27: Value Added Chain

Figure 28: Calculate Cost Accruals Event-Driven Process Chain

Figure 29: Plan Scope Function Allocation Diagram

Figure 30: Plan Scope Function Allocation Diagram


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v

Nomenclatures

1.NR Natural Rubber

2.RPL Roop polymers limited

3.TPE Thermoplastic rubber

4. PP Polypropylene

5.PVC Polyvinylchloride

6.PLC Programmable logic controller

7.TIP Technology innovation

programme

8.ICS Industrial control system

9. DCS Distributed control systems

10.NC Numerical control

11.ROI Return on investment

vi
http://en.wikipedia.org/wiki/Industrial_control_systemhttp://en.wikipedia.org/wiki/Industrial_control_systemhttp://en.wikipedia.org/wiki/Numerical_controlhttp://en.wikipedia.org/wiki/Numerical_controlhttp://en.wikipedia.org/wiki/Numerical_controlhttp://en.wikipedia.org/wiki/Industrial_control_system


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CHAPTER 1

INTRODUCTION


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1.1.Objectives of the projectThe purpose of project management is to foresee or predict as many dangers and problems as

possible. And to plan, organise and control activities so that the project is completed as

successfully as possible in spite of all the risks.

1. Commissioning of the whole factory

2. Optimization and Automation of the production process

By Managing resources:

a. Maintain Time and progress

b. Quality and performance

c. Cost and cash flow

The main objectives of optimization of manufacturing process and remodelling old machines and

production lines are:

Increase in productivity Increase in product reproducibility and product quality Decrease in the influence of human factors on product quality Facilitating operators and maintenance personnel work Increase in safety at the workplace

1.2.Success parameters of the project Performance and Quality:

The end result of a project must fit the purpose for which it was intended. In more recent years

the concept of total quality management has come to the fore, with the responsibility for quality

shared by all staff from top management downwards.

Budget:The project must be completed without exceeding the authorised expenditure. Financial sources

are not always inexhaustible and a project might be abandoned altogether if funds run out before


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completion. If that was to happen, the money and effort invested in the project would be forfeited

and written off.

Time to Completion:Actual progress has to match or beat planned progress. All significant stages of the project must

take place no later than their specified dates, to result in total completion on or before the

planned finish date.

Manpower: Efficient use of human resources.Production: To achieve high production in a given time and to extract maximum from the

production process.

Cost analysis:-To determine if it is a sound investment/decision (justification/feasibility),

-To provide a basis for comparing projects. It involves comparing the total expected cost of each

option against the total expected benefits, to see whether the benefits outweigh the costs, and by

how much.

Inventory: To reduce the inventory cost by providing just in time based production by

automation and optimization of the on-going process. It is required at different locations within a

facility or within many locations of a supply network to precede the regular and planned course

of production and stock of materials.

1.3.Brief Introduction of the projectProcess optimization is the discipline of adjusting a process so as to optimize some specified set

of parameters without violating some constraint. The most common goals are minimizing cost,

maximizing throughput, and/or efficiency. This is one of the majorquantitativetools in industrial

decision making.
http://en.wikipedia.org/wiki/Quantitative_propertyhttp://en.wikipedia.org/wiki/Quantitative_propertyhttp://en.wikipedia.org/wiki/Quantitative_propertyhttp://en.wikipedia.org/wiki/Quantitative_property


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When optimizing a process, the goal is to maximize one or more of the process specifications,

while keeping all others within their constraints.

The idea behind process optimization is to modify a process as to deliver higher yield, more

product or higher return from existing assets or people.

Businesses and process managers need to work on process optimization at various stages during

manufacturing (but not limited to manufacturing). The best companies continue to strive for

continuous process optimization exercises throughout their existence.

Act of process optimization describes use of various methods to maximize return, cycle time,

yield, or efficiency given multiple constraints. There are three parameters that can be adjusted to

affect optimal performance. They are:

Equipment optimization

The first step is to verify that the existing equipment is being used to its fullest advantage by

examining operating data to identify equipment bottlenecks.

Operating procedures

Operating procedures may vary widely from person-to-person or from shift-to-shift. Automation

of the plant can help significantly. But automation will be of no help if the operators take control

and run the plant in manual.

Control optimization

If the control loop is not properly designed and tuned, the process runs below its optimum. The

process will be more expensive to operate, and equipment will wear out prematurely. For each

control loop to run optimally, identification of sensor, valve, and tuning problems is important.

The process of continuously monitoring and optimizing the entire plant is sometimes called

performance supervision.
http://en.wikipedia.org/wiki/Control_loophttp://en.wikipedia.org/wiki/Control_loop


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Figure 1: Process Improvement


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1.4.Process Optimization ToolMany relate process optimization directly to use of statistical techniques to identify the optimum

solution. Statistical techniques are definitely needed. However, a thorough understanding of the

process is required prior to committing time to optimize it. Once the process inputs, outputs and

intermediate responses are recognized for each step, one needs to confirm the relationships.

1.5.Value PropositionUnderstanding business process steps with the goal of identifying areas of improvement and

eliminating inefficiency in order to simplify, integrate and automate. Processes are the key

enabler to both effectiveness and efficiency of a operation. Both tool selection and organizational

alignment should be based on optimized and clearly communicated processes.

1.6.Steps of process optimization1. Understand what the process is trying to accomplishThe processes should be clearly defined in order to adopt the process management concept in an

organization. The processes are generally categorized under these three headings:

Operational processes

Managerial processes Quality processes

2. Map ProcessesThe design of process maps includes identification of:

Process owners Parent processes Sub-processes Process flow and steps Roles, conditions, and rights related to steps The essential information and other relevant input for a seamless process flow Process outputs


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3. Categorize Steps as Value Added or Non-Value Added For Value Added Activity

THE DEVELOPMENT OF POOR QUALITY COSTS

For many years quality costs were divided into prevention costs, appraisal costs, internal failure

costs and external failure costs, first identified by Feigenbaum (1956). Prevention costs and

appraisal costs are those that management has direct control over to ensure that only customer-

acceptable products and services are delivered to the customer. All the company-incurred costs

that result from errors include internal and external error costs.

These costs are directly related to management decisions made in the prevention and appraisalcost categories. Feigenbaum considered external failure costs as more serious than internal

failure costs, because it may result in more disappointed customers. This traditional

categorization has been widely used, for example in the ISO 9000 standard. Sometimes the term

poor quality costs (PQC) is used because it is poor quality, not quality, that causes extra costs.

A number of researchers have tried to further develop Feigenbaums model by adding new

categories. But no one has so far been widely accepted. Modarres and Ansari (1985), who added

cost of quality design and cost of inefficient utilization of resources, and Sugiura (1997, referred

in Giakatis et al., 2001), who added adjustment cost and quality design cost, are just two such

examples.

The concept of poor quality costs began to change its focus to more consider the customers

needs during the 1980s. Harrington (1987) differentiated between direct PQC and indirect PQC.

He used the term direct PQC for the four traditional categories. When using the term indirect

poor-quality costs Harrington considered the customers different and individual requirements.

He defined indirect PQC as those costs not directly measurable in the company ledger, but part

of the product life cycle PQC and divided it into three major categories. Customer-incurred

PQC appears when an output fails to meet the customers expectations. Customer-dissatisfaction

PQC is lost income because customers are not satisfied with the companys product and

therefore choose a competitors product next time.


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POOR QUALITY COSTS IN CONSTRUCTION

It is evident that we lack knowledge of poor quality costs in construction. We have knowledge of

the visible costs, but lack knowledge of most of the hidden costs, lost income, customers costs

and socio-economic costs. We probably lack necessary knowledge to be able to see and

understand the hidden costs (Josephson, 2000). We probably also lack knowledge of the size of

other non-value-adding activities. We must broaden our views and question the existing and

accepted activities and behaviour in projects.

Non Value Added ActivityNO GENERALLY ACCEPTED CATEGORIZATION

Many different categorizations have been used in the studies of poor quality costs in

construction. But there is so far no generally accepted system. Typical questions dealt with

include (e.g. Davis, 1987; Josephson, 1994; Love and Irani, 2002)

When did it happen? (Date or phase of project)

When was it detected? (Date or phase of project)

Who detected it? (Actor)

Who caused it? (Actor)

What type of immediate cause? (On individual level, e.g. knowledge, information, engagement,

etc.)

What type of root-cause? (E.g. organisation)

What type of problem?

What type of incident? (E.g. error, change, omission)

In what element of the building? (Structure, interior design, etc.)


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In which activity?

Who corrected it? (Actor)

When was it corrected? (Date)

Which effect on the project? (Delay, extra cost, etc.)

Who paid it? (Actor)

The categorizations used are dependent on the approach taken by the researcher. Most common

is a company approach or a project approach (e.g. Josephson and Hammarlund, 1999). An

industry approach or a national approach (e.g. Halevy and Naveh, 2000) is uncommon. Burati et

al. (1992) classified deviations in errors, omissions and changes.

4. Identify Improvements5. Define Cost Savings Opportunities6. Conduct External Benchmarking Research7. Define Recommendations & Action Plan


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Figure 2: Steps of Process Optimization


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1.7 Roop Polymers Pvt Ltd (Company Profile)

Established in 1973 in the automotive industrial hub of Gurgaon, Roop Polymers Ltd. (RPL) is

the flagship company of the Roop Group. With over 35 years of rich experience in the

automotive industry, RPL today is a world class manufacturer of Moulded and Extruded Rubber

& Plastic parts for Automotive OEM around the globe. It operates through 6 state of the art

manufacturing facilities which are strategically located near the OEM customer base in Gurgaon,

Sohna & IMT Manesar in Haryana and Pantnagar in Uttranchal. All the RPL plants are TS-

16949 & ISO 14001 certified and meet the most stringent quality norms set by its diverse range

of customers. Apart from supplying to automotive majors in India like Maruti Suzuki, Honda,Hero Honda, Bajaj Auto etc., RPL is also a major supplier to TRW, USA for their critical rubber

parts requirement.

RPL has a unique capability to process rubber parts in all grades like NR, NBR, SBR, EPDM,

Silicon, Viton, Neoprene, Chloroprene, HNBR, Fluoro, Isoprene, Hyplone, etc., and plastic parts

in grades like PP (Polypropylen), PVC (Polyvinylchlorid), TPE (Thermoplastic rubber), PA 66,

PA66 + Glass Fibre, POM (Polyoxymethylen), Santoprene, Desmopan, etc. It therefore offers a

'one stop shop' engineering solutions to all the customers through its expertise in designing,

development, tooling, moulding, extrusion, assembly, painting, testing and delivery capabilities

across the globe. Backed by its technical capabilities and highly enthusiastic workforce, RPL

today has become a supplier of choice for the Indian Automotive industry.


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CHAPTER 2

GENERAL PROCESS OF MAKING A RUBBER COMPONENT


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While the first rubber product manufacturers were the indigenous people of the Amazon basin,

Europeans started to experiment with rubber product manufacturing during the nineteenth

century as a method to make waterproof footwear and other types of waterproof clothing and

equipment. This early rubber product manufacturing was relatively small scale until Charles

Goodyear invented vulcanization in 1839. Vulcanization is a technique utilized by rubber

product manufacturers which modifies the chemical structure of rubber so that it is strong

enough to withstand extreme heat and cold, making it highly effective in all kinds of industrial

applications. Rubber soon became vital to all kinds of industrial design, exponentially increasing

the scale of rubber product manufacturing.

2.1. Products and Raw materials used

Products made from rubber have a flexible and stable 3dimensional chemical structure and are

able to withstand under force large deformations. For example the material can be stretched

repeatedly to at least twice its original length and, upon immediate release of the stress, will

return with force to approximately its original length.

Under load the product should not show creep or relaxation. Besides these properties the

modulus of rubber is from hundred to ten thousand times lower compared to other solid materials

like steel, plastics and ceramics. This combination of unique properties gives rubber its specific

applications like seals, shock absorbers and tyres.

Rubber is used as a name for 3 categories:

Raw or base polymers: These determine the main characteristics of the final product.

Semi-manufactured: product

The addition to raw rubber of various chemicals, to impart desirable properties, is termed

compounding. This semi-finished material is getting its rubber properties after vulcanization.

Final product: After moulding the rubber compounds gets its elastic properties after a

vulcanisation process.

Modern rubber materials consist of approximately 60 percent of synthetic polymers. The otherpart consists of vulcanisation agents, softeners, accelerators, anti-aging agents and other

chemicals. These additions are necessary to achieve the desired properties of the final product.


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Non vulcanised phase vulcanised phase

Figure 3: Bonded flexible chains

Polymers have a backbone of hydrocarbons. The hydrogen atom is often replaced by other atoms

or molecules (like CH3, Cl or F) and thus creates another type of elastomer. These chains are

chemically bonded together by sulphur, peroxides or biphenyl. An exception is silicone. Silicone

contains very flexible siloxane backbones (Si-O) and can be cured with peroxide or platinum-

catalyst curing.

The most common elastomers are:

Ethylene Propylene Rubber (EPDM/EPM)

EPM is a copolymer of ethylene and propylene. This type can only be cross-linked with

peroxides. If during the copolymerization of ethylene and propylene, a third monomer, a diene, is

added the resulting rubber will have unsaturation and it can then be vulcanized with sulphur.

These rubbers are the so-called EPDMs.

The main properties of EPDM are its outstanding heat, ozone and weather resistance. The

resistance to polar substances and steam are also good. It has excellent electrical insulating

properties. The EPDM copolymer can be filled with more than 200 per cent of its own weight

with non-re-in forcing fillers, resulting in reduction of cost price but also in physical properties.

For these reasons this rubber is widely applied in many applications.


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Nitrile rubber (NBR)

NBR is a family of unsaturated copolymers of acrylonnitrile (CAN) and butadiene monomers.

Although its physical and chemical properties vary depending on the polymers composition of

nitrile (the more nitrile within the polymer, the higher the resistance to oils but the lower the

flexibility of the material), this form of synthetic rubber is generally resistant to oil, fuel, and

other chemicals. It is used in the automotive industry to make fuel and oil handling hoses, seals,

and grommets.

NBRs ability to withstand a range of temperatures from -40 C to +108 C makes it an ideal

material for automotive applications. Nitrile rubber is more resistant than natural rubber to oils

and acids, but has less strength and flexibility. Nitrile rubber is generally resistant to aliphatic

hydrocarbons. Nitrile, like natural rubber, can be attacked by ozone, aromatic hydrocarbons,

ketones, esters and aldehydes.

Natural Rubber (NR)

Natural rubber has a very high elasticity, high tensile strength and a very good abrasion

resistance. The material is obtained by coagulation of latex derived from the rubber tree. The

rubber is not resistant to aging and oil. For these reasons NR is rarely used as a seal for technical

applications, but is mixed with other elastomere compounds like EPDM to improve rubber

properties.

Styrene - Butadien Rubber (SBR)SBR is a synthetic rubber copolymer consisting of styrene and butadiene. It has good abrasion

resistance and good aging stability when protected by additives, and is widely used in car tyres,

where it is blended with natural rubber.

Chloroprene rubber (CR)

Commonly known under the trade name Neoprene of Dupont. CR is not characterised by one

outstanding property, but its balance of properties is unique among the synthetic elastomers. It

has good mechanical strength, high ozone and weather resistance, good aging resistance, low

flammability, good resistance toward chemicals and moderate oil and fuel resistance.

Silicone (VMQ/MVQ/HTV)

Silicones differ from other polymers in that their backbones consist of Si-O-Si units unlike many

other polymers that contain carbon backbones.


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Silicone rubber offers good resistance to extreme temperatures, being able to operate normally

from -55 C to +230 C. At the extreme temperatures, the tensile strength, elongation, tear

strength and compression set can be far superior to conventional rubbers although still low

relative to other materials. Organic rubber has a carbon to carbon backbone which can leave

them susceptible to ozone, UV, heat and other ageing factors that silicone rubber can withstand

well. This makes it one of the elastomers of choice in many extreme environments.

Compared to organic rubbers, however, the tensile strength of standard silicone rubber is lower.

For this reason, care is needed in designing products to withstand low imposed loads. Nowadays

also silicone compounds with improved tensile strength are available.

Acrylic rubber (ACM)

Acrylic rubber, known by the chemical name alkyl acrylate copolymer (ACM), is a type of

rubber that has outstanding resistance to hot oil and oxidation. It has a continuous working

temperature of 150 C and an intermittent limit of 180 C. Disadvantages are its low resistance to

moisture, acids, and bases.

It should not be used in temperatures below -10 C. It is commonly used in automotive

transmissions and hoses.

Hydrogenated Nitrile Butadiene Rubber (HNBR)

The properties of hydrogenated nitrile rubber depend on the acrylonitrile (ACN) content, and on

the degree of hydrogenation. They can be tailored to particular applications, but have the

general advantage over standard nitrile rubber of having higher temperature resistance and higher

strength.

HNBRs also have good high temperature oil and chemical resistance and are resistant to amines.

They are suitable for use in methanol and methanol/hydrocarbon mixtures if the correct ACN

level is selected. They have good resistance to hot water and steam. They can have excellent

mechanical properties including strength, elongation, tear resistance, abrasion resistance and

compression set.

For the best properties peroxide curing is used, unless low hysteresis is required. They are

reported to be satisfactory up to temperatures around 180 C in oil. Fully saturated grades have

excellent ozone resistance. They have poor resistance to some oxygenated solvents and aromatic

hydrocarbons.


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Fluoro rubber (FKM)

Fluoroelastomers are a class of synthetic rubber which provide extraordinary levels of resistance

to chemicals, oil and heat, while providing useful service life above 204C. The outstanding heat

stability and excellent oil resistance of these materials are due to the high ratio of fluorine to

hydrogen, the strength of the carbon-fluorine bond, and the absence of unsaturation.

The original fluoroelastomer was a copolymer of hexafluoropropylene (HFP) and vinylidene

fluoride (VF2). It was developed by the DuPont Company in 1957 in response to high

performance sealing needs in the aerospace industry. To provide even greater thermal stability

and solvent resistance, tetrafluoroethylene (TFE) containing fluoroelastomer terpolymers were

introduced in 1959 and in the mid to late 1960s lower viscosity versions of FKMs were

introduced A breakthrough in cross linking occurred with the introduction of the bisphenol cure

system in the 1970s. This bisphenol cure system offered much improved heat and compression

set resistance with better scorch safety and faster cures speed. In the late 70s and early 80s

fluoroelastomers with improved low temperature flexibility were Introduced by using

perfluoromethylvinyl ether (PMVE) in place of HFP, Fluoroelastomers are a family of

fluoropolymer rubbers, not a single entity. Fluoroelastomers can be classified by their fluorine

content, 66%, 68% and 70% respectively. Fluoroelastomers having higher fluorine content have

increasing fluids resistance derived from increasing fluorine levels. Peroxide cured

fluoroelastomers have inherently better water, steam, and acid resistance.

Fluoroelastomers are used in a wide variety of high-performance applications. FKM provides

premium, long-term reliability even in harsh environments. A partial listing of current end use

applications (industries like aerospace and automotive) include: O-ring seals in fuels, lubricants

and hydraulic systems, shaft seals, valve stem seals, fuel injector O-rings, diaphragms, lathe cut

gaskets and cut gaskets.

A rubber compound is obtained by mixing a base polymer or crude mixture with a series of

additives.

The choice of the base polymer and the additives is closely linked to the type of properties to be

Achieved. The resulting product is a non-vulcanized compound. The quantity of additives used

varies for 20 to 130 percent as a percentage on the weight. The most common additives are:


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Fillers

There are two types of fillers, reinforcing and non-reinforcing fillers. Carbon black is commonly

used as reinforcing filler. This is also the reason why most rubbers are black. Calcium carbonate

is an example of a non-reinforcing filler.

Plasticizers

Besides fillers, plasticizers play the biggest quantitative role in building a rubber compound. The

reasons for the use of plasticizers are: improvement of flow of the rubber during processing,

improved filler dispersion, influence on the physical properties of the vulcanizate at low

temperatures. Mineral oils and paraffins are widely used as a plasticizer.

Vulcanization chemicals

Vulcanization is the conversion of rubber molecules into a network by formation of crosslinks.

Vulcanizing agents are necessary for the crosslink formation. These vulcanizing agents are

mostly sulphur or peroxide and sometimes other special vulcanizing agents or high energy

radiation. Since vulcanization is the process of converting the gum-elastic raw material into the

rubber-elastic end product, the ultimate properties like hardness and elasticity depend on the

course of the vulcanization.

Accelerators

Accelerating agents increase the rate of the cross linking reaction and lower the sulphur content

necessary to achieve optimum vulcanizate properties.

Activators

Like zinc-oxide and stearic acid. They activate the vulcanisation process and help the

accelerators to achieve their full potential.

Anti-degrading agents

These agents increase the resistance to attacks of ozone, UV light and oxygen.

Process aids

Chemicals that improve the process ability

Pigments

Organic and inorganic pigments are used to colour rubber compounds. The colour pigments are

also considered inactive fillers. Only silicas have a reinforcing effect. Silicone can be coloured

easily without loss of properties.


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2.2. General Process of manufacturing of rubber component

Moulded rubber parts can be produced by different manufacturing methods. Major techniques

are:

Compression moulding

Compression moulding is a process in which a compound is squeezed into a preheated mould

taking a shape of the mould cavity and performing curing due to heat and pressure applied to the

material. The method uses a split mould mounted in a hydraulic press

Compression moulding process involves the following steps:

1. A pre-weighed amount of the compound is placed into the lower half of the mould. The

compound may be in form of putty-like masses or pre-formed blanks.

2. The upper half of the mould moves downwards, pressing on the compound and forcing it to

fill the mould cavity. The mould, equipped with a heating system, provides curing (cross-linking)

of the compound

3. The mould is opened and the part is removed for necessary secondary operations.

Figure 4: Compression Modelling


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Injection moulding

Injection moulding is a process in which the compound is forced under high pressure into a

mould cavity through an opening (sprue).

The rubber material in form of strips is fed into an injection moulding machine. The material is

then conveyed forward by a feeding screw and forced into a split mould, filling its cavity through

a feeding system with sprue gate and runners.

An injection moulding machine is similar to an extruder. The main difference between the two

machines is in screw operation. In the extruder type the screw rotates continuously providing

output of continuous long product (pipe, rod, sheet).The screw of the injection moulding

machine is called a reciprocating screw since it not only rotates but also moves forward and

backward according to the steps of the moulding cycle.

It acts as a ram in the filling step when the compound is injected into the mould and then it

retracts backward in the moulding step. The mould is equipped with a heating system providing

controlled heating and vulcanization of the material.

The compound is held in the mould until the vulcanization has completed and then the mould

opens and the part is removed from the mould.

Injection moulding is a highly productive method providing high accuracy and control of shape

of the manufactured parts. The method is profitable in mass production of large number of

identical parts. A principal scheme of an injection moulding machine is shown here.


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Figure 5: Injection Modelling


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Transfer moulding

Transfer moulding is a process in which a pre-weighed amount of a compound is preheated in a

separate chamber (transfer pot) and then forced into a preheated mould through a sprue, taking a

shape of the mould cavity and performing curing due to heat and pressure applied to the material.

The picture below illustrates the transfer moulding process.

The method uses a split mould and a third plate equipped with a plunger mounted in a hydraulic

press. The method combines features of both compression moulding (hydraulic pressing) and

injection moulding (ram-plunger and filling the mould through a sprue).

The transfer moulding process involves the following steps:

1. A pre-weighed amount of a compound is placed into the transfer pot. The compound form

putty-like masses or pre-formed blanks. The compound is heated in the pot where the material

softens.

2. The plunger, mounted on the top plate, moves downwards, pressing on the material and

forcing it to fill the mould cavity through the sprue. The mould, equipped with a heating system,

provides curing (cross-linking) of the compound.

3. The mould is opened and the parts are removed for necessary secondary operations the scrap

left on the pot bottom (cull), in the sprue and in the channels is removed. Scrap of vulcanized

rubber is not recyclable.


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Figure 6: Transfer Modelling

The transfer moulding cycle time is shorter than compression moulding cycle but longer than the

injection moulding cycle. The method is capable to produce more complicated shapes than

compression moulding but not as complicated as injection moulding.

Transfer moulding is suitable for moulding with ceramic or metallic inserts which are placed in

the mould cavity. When the heated compound fills the mould it forms bonding with the insert

surface.


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More In detail, available production techniques are summarized in the next table.


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Secondary finishing

Depending on the requirements and production process, some secondary finishing steps might be

necessary or required:

After vulcanisation

Some rubber types require a process of after vulcanisation (heating) for some hours. HNBR and

FKM rubber is after vulcanised to give the rubber its optimal mechanical properties after

moulding.

Post curing

Silicones parts applied in food or medical applications are mostly post cured after moulding.

Post- curing is one of the principal tools to mitigate outgassing. Post-cure is a process that

removes the volatiles from the cross-linked silicone rubber by diffusion and evaporation and is

carried out at a temperature greater than the service temperature for the part. Post-curing also

helps to improve the compression set.

Cryogene finishing

Cryogene deflashing and deburring is a step that is meant to remove excess imperfections on

moulded parts such as fleece or flash lines. The process uses liquid nitrogen, high speed rotation

and media (shot blast) in varying combinations to remove the flash in a highly precise and

expedient manner.

In the extrusion process of rubber, the compound including polymers, various types of additives

and fills like curing agents, antioxidants, pigments are fed into the extruder. The extruder

typically consists of a rotating screw inside a closely fitted heated barrel. The primary purpose of

the extruder is to do three things, a) soften, b) mix, c) pressurize the rubber as it is fed

continuously to the die at the extruder exit.

The die is a sort of metal disk that has a machined opening in the desired shape of the part that

needs to be extruded. The rubber already softened by heating is then forced by the rotating screw


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through the die opening into the shape of the profile cut in the die. A typical phenomenon called

die swell takes place as the rubber shape leaves the die. Because of this the part cross-section

becomes larger than the die cross-section. The part cross-section depending on the material may

rise up to several folds over the die.

Subsequently the processes of vulcanization or curing takes place as the last step in the extrusion

process. This aids the rubber extruded profiles to maintain its shape and acquire necessary

physical properties. Typical examples of extruded rubber parts are profiles, hoses, strips and

cords.

Incoming Material

Compund

Mixing 1 Master

Batching

Mixing 2 & Milling

Shaping

Cure


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Figure 7: General Process

Figure 8: Major Process of Rubber


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CHAPTER 3

LITRATURE REVIEW


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Moving particulate materials in liquid slurry form can seriously erode their containers. Turbo

machines are increasingly being applied to extensive industrial fields and tend to be operated at

higher rotational speed. Therefore, to maintain high performance over a long time, it is desirable

to pay attention to the wear. Erosive wear in centrifugal slurry pumps has motivated many

researchers, due to its application in areas such as dredging, hydraulic transport etc.

Experimental results concerning the wear of slurry pump impellers are not abundant. A variety

of bench scale test rigs have been used by the investigators to predict the erosion wear. Most of

them have used Slurry Pot Tester which comprises of a cylindrical tank in which wear specimens

are tested against wear. These test rigs require the solid-liquid suspension to be uniform and

vortex free. Therefore, detailed study of solid-liquid suspension system in an erosion wear test

rig is required. This has initiated researchers to conduct research on wear as well as on the solid-

liquid suspension system of wear test rigs. A review of literature available in this area has been

presented in the following paragraphs to discuss the present state of knowledge.

Shawky M. et al1 [1989] presents some experimental results of erosive wear in a centrifugal

slurry pump. The objective of their investigation was to study the relation between erosive wear

in a centrifugal pump impeller and solid particle concentration. The erosion rate of a centrifugal

pump impeller is measured by the weighing method. They have used two different concentration

of coarse sand and have investigated the effect of speed of rotation.

The experimental results obtained by them show the correlation between the erosive wear

development and solid particle concentration.

Desai P.V2 [1990] has studied the erosion wear of centrifugal slurry pumps which is primarily

governed by the particulate motion and concentration as well as their physical properties. The

analysis and the finite element computations yield the solid velocity and concentration fields in

an arbitrary radial cross-section of a centrifugal slurry pump casing.

The solutions were examined in light of their applicability to the pump wear problem. Axis

symmetric finite elements have to be used to analyse the flow in the volume of revolution. The

shape factor of the particles is introduced into the drag and pressure force calculations to account

for the angularity of the particles.


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Hector McI. Clark3 [1991] has pointed out the importance of knowledge of flow field

surrounding impinging particles and target is emphasized for an understanding of slurry erosion.

He has reviewed the work on the effect of liquid viscosity and density, particle size and size

range, density and concentration, target shape and suspension free stream velocity in slurry

erosion. His studies show that the experimental data on the material erosion rates can only be

understood if particle impact velocities and trajectories and the number of particles impacting the

target surface are known. He has pointed out that the actual impact velocities of the particles on

an eroding target may differ widely from the free stream velocity of the suspension and that

under some circumstances most, or even all, particles directed at a target may fail to collide with

it.

Steward N.R. et al4 [1992] have emphasized on the pipeline wear which continues to be an area

of specific concern, since it constitutes a major cost during the life of a pipeline installation.

Wear data from an accelerated wear test and actual pipeline tests have been presented by them.

Trends in the performance of the pipeline materials tested are discussed, and possible solutions

to the problem of pipeline wear are presented.

Neseic.S. et al5 [1993] have evaluated erosion rates along the length of a tubular flow cell of

type 304 (UNS S30400) stainless steel (SS) carrying dilute slurries of silica sand (0.43 mm diam)

and smooth glass beads of a similar size. The segmented test cell contained a sudden

constriction, a sudden expansion, and a groove to produce disturbed flow conditions. Erosion

rates were reduced by changes in the cell wall geometry that resulted from erosion at positions of

high local metal loss and from erosion further downstream because of the reduction in turbulence

and particle dispersion.

Gupta Rajat et al6 [1994] have conducted a systematic study on a pot tester to establish the

effect of velocity, concentration and particle size on erosion wear. Two correlations have been

proposed, based on the data generated for equisized particulate slurries in the pot tester, to

predict the expected erosion wear for two pipe materials, namely brass and mild steel. The

1eighted mean diameter has been established as the best representative diameter for the

multisided particulate slurries. The proposed correlations have been used to predict the extent of

uneven erosion wear in a slurry pipeline using local concentration, local effective particle size

and average velocity. The comparison between predicted and experimental results shows

agreement within 13.5% for brass and + 14% for mild steel.


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Zhong Yuan et al7 [1995] have followed Lagrangian approach to predict the erosion wear on a

pump casing wall due to impingement of solid particles and calculated the impinging velocities

on the casing wall under the assumption that the water flow field remains unchanged due to the

presence of the particles. They have also investigated the effect of mutual collision among the

particles. Their result showed that the impinging velocities of the particles in the tongue area

have remarkably a large normal component with no tangential one. Distribution of the

volumetric particle concentration is hardly affected by the spinning and mutual collisions of the

particles.

Zhong Yuan et al8 [1996] have measured erosion damage of wear resistant materials due to

sand particle impingement and correlated based on Bitters erosion model to clarify the effects of

particle impinging velocity and angle, particle size and concentration on the wear.

Using the empirical formula for the correlation and calculating impinging velocities of sand

particles on a casing wall of a pump, successive erosion of the wall is numerically calculated o

demonstrate the viability of the prediction method. The erosion data of cast iron and stainless

steel eroded by sand particles confirm Bitters erosion model.

Stokes et al9 [1999] have used axis-symmetric model to simulate two-phase flows in stirred

mixing tank. The impeller used is Rushton turbine. They have studied the gas-water two phase

flow and have used RNG based k- turbulent model in their computational study. The numerical

solution of the radial, tangential and axial velocities of the air was compared with the

experimental results.

Brown Gary et al10 [1999] have studied tee junctions in a slurry pipeline system. The

commercial code ANSYS-CFX has been used to predict the motion of caustic liquor and bauxite

particle through a tee-junction using an Eulerian-Eulerian continuum approach in conjunction

with k- turbulence model. The predicted wear location was found to be insensitive to the

assumed level of inlet swirl and the numerical scheme employed.

Lee S. Y. et al11 [2001] have discussed the application of computational fluid dynamics (CFD)

methods to simulate the flow of slurry and predict the erosion rates so that an effective

maintenance schedule can be developed for the filtration system of the waste treatment process.

The location of the maximum erosion for the selected components is also identified.


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Solids content of the working fluid, the regions of high wall shear, and particle impingement

with the walls were considered as major mechanisms associated with the erosion. All these tests

were performed using sand water slurry.

Hawthorne H.M. et al12 [2001] has conducted Coriolis tests for the evaluation of slurry erosion

on different materials. Slurries consisting of glass beads of size 90- 200 micron size with 10%

slurry concentration were taken and tests were performed on 1020 steel and copper at different

impingement angles of 90-20 degrees. It was also observed that in slurry jet testing, most

particles impact the specimen above its critical velocity resulting severe plastic deformation. In

contrast, in the Coriolis test most particle impacts result in only elastic deformation or mild

plastic deformation. Hence, elastic as well as plastic properties of specimen materials affect their

performance in a Coriolis slurry erosion evaluation, thus the results obtained from Coriolis tests

were more accurate.

Gandhi B. K. et al13 [2001] have studied that the performance of pumps decreases for increase

in solid concentration, particle size and specific gravity. The head and efficiency of the pump

decrease with increase in solid concentration, particle size, and slurry viscosity, the decrease in

the head being 210 per cent higher than that of the efficiency. The presence of finer particles

(less than 18micron) in coarser slurries substantially attenuates the loss of performance of the

pump in terms of head and efficiency. At low solid concentrations less than 30 per cent by

weight, the increase in the pump input power is directly proportional to the specific gravity of

slurry whereas the same relationship is not applicable at higher concentrations. The study on the

pumps has confirmed that the additional head loss for slurries decrease with increase in the pump

size.

L.M. oshinowo et al14 [2002] have studied the effect of computational fluid dynamics approach

to evaluate solid suspension in stirred tanks. The distribution of solids in stirred tanks under a

range of solids loadings (0.5 to 50 vol%) was predicted using CFD and validated against

experimental data obtained from the literature. The multiphase flow is modelled using the

Eulerian Granular Multiphase model. They have studied the performance of hydrofoil impellers

and a 45 pitched-blade turbine at suspending solids under different agitation speeds. The

standard deviation of solids volume fraction was shown to be useful measure of the quality of

suspension.


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D. Chapple et al15 [2002] have studied the effect of impeller and tank geometry on power

number for a pitched blade turbine. The changes done in the position of the impeller in the tank

can have a significant impact on the power number (15%) due to changes in the flow patterns.

They have shown that there is no effect of the blade thickness on the power number for a four

blade PBT 45 degrees impeller.

Litian et al16 [2003] have conducted Computational Fluid Dynamics study of Rushton turbine

in stirred tanks. The commercial code used by them was ANSYS-CFX. To account for the

relative movement between impeller and baffles sliding mesh method has been used by them.

Fluid flow is calculated with a turbulent k- and RNG k- model using finite volume method.

Their result show that mixing time highly relies on the flow field, the feeding and detection

position.

Feng Wang et al17 [2003] studied CFD simulation of solid-liquid two phase flow in baffled

stirred vessel with Rushton Impellers. They have simulated three dimensional flow field and

solid concentration distribution in solid liquid baffled stirred vessels using inner-outer iterative

procedure. The procedure used by them can be applied to the system with high solid

concentration upto 20%.

J. J. Derksen et al18 [2003] have numerically simulated the solid suspension in the strirred tank.

Large-eddy simulations of the turbulent flow driven by a Rushton turbine have been coupled to a

Lagrangian description of spherical, solid particles immersed in the flow. The working fluid was

water, whereas the solid particles had the properties of glass beads. It has been investigated to

what level of detail the particle motion needs to be modeled in order to meet Zwieterings just

suspended criterion.Their result show that it is essential to take article-particle collisions into

account, mainly because of their exclusion effect that prevents unrealistic buildup of particle

concentrations closely above the bottom.

Gandhi B. K. et al19 [2004] have developed a methodology to determine the nominal particle

size of multi-sized particulate slurry for estimation of mass loss due to the erosion wear. The

effect of presence of finer particles (less than 75 micron) in relatively coarse particulate slurry

has also been studied. They have observed that addition of particles finer than 75 micron in

narrow-size or multi-sized slurries reduce the erosion wear. In addition, the effective particle size

for narrow-size particulate slurries can be taken as the mean size whereas the weighted mass

particle size seems to be a better choice for multi-sized particulate slurries. The reductions in


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erosion wear due to addition of fine particles decreases with increase in the concentration of

coarse size particles.

Wood R.J.K. et al20 [2004] has covered research that has been aimed at determining the

distribution of erosion rates and the erosion mechanisms that occur over wetted surfaces within

pilot scale pipe systems handling water-sand mixtures at 10% by volume concentrations and at a

mean fluid velocity of approximately 3 m/s. The wall wear rates, obtained by gravimetric

measurements, as a function of time are discussed. The erosion rates, expressed as volume loss

per impact (determined gravimetrically and via computer models) in bends are found to agree

well with simple laboratory scale water-sand jet impingement tests on planar stainless steel

samples.

G. Montante et al21 [2005] have studied the solid liquid multiphase flow in tall stirred vessels

with multiple impeller systems. Good results were obtained using eddy viscosity turbulence

models for fully baffled vessels. Their results recommend the use of Magelli drag correction for

prediction of solid concentration in stirred vessels.

R. Thorpe et al22 [2005] have conducted studies on the suspension of particles from the bottom

of pipes and stirred tanks by gassed and ungassed flows. They have concluded that pick-up in

pipes involves viscous sublayers where turbulent forces are not dominat force.

They have compared the correlations and theoretical predictions for hydraulic conveying of

solids in pipelines with the literature on the suspension of particles in stirred tanks.

Dolman K.F. et al23 [2005] have studied the ameliorative influence on scouring erosion

behaviour of high carbon content, hardness and carbide volume fraction and particularly of fine

carbide size. They have drawn a correlation between test data and service performance.

Low impact angle erosion resistance is a critical requirement of materials used in pumps, piping,

valves, nozzles, cyclones and other components which transport and process most mineral

slurries. The specific method used in their study involves high velocity erosion with aqueous

slurry containing 10 wt. % of AFS 50-70 silica test sand. The test is considered to be a suitable

method for evaluating the scouring erosion resistance of metallic, ceramic and cermet materials

for various slurry transport components.

Sellgren A. et al24 [2005] have modeled a selection of pump designs producing general

relationships for the different pump casing, impeller and liner components for different duties.

They then take these and show which offer the lowest cost of ownership for different services.


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Correlations against pump design specific speed show higher specific speed pump casings wear

better, while lower specific speed, slower running, larger diameter impeller pumps have better

impeller and liner wear. The calculated values show total cost of ownership is affected

significantly by changes in operating conditions (due to wear) and is a minimum, in most cases,

at around a design specific speed of NS=38 (2000 USNS).

T. Kumaresan et al25 [2005] have studied the effect of internals on the flow pattern and mixing

in the stirred tanks. Measurements of power consumption, mixing time, and flow pattern have

been carried out in a stirred vessel of 0.5 m diameter for a standard 45 pitched blade turbine and

for a hydrofoil impeller with a variety of baffle and draft tube configurations. The comparison of

the flow pattern (average velocity, turbulent kinetic energy, maximum energy dissipation rate,

average shear rate, and turbulent normal stress) has been presented on the basis of equal power

consumption to illustrate the extent of interaction between the rotating impeller and the internals.

Comparisons of laser Doppler anemometer (LDA) measurements and computational fluid

dynamics (CFD) predictions have been presented.

Tian Harry H. et al26 [2005] have observed the erosive wear of some metallic materials such as

high chromium white iron and aluminium alloy using Coriolis wear testing approach. In the

present study, the correlation between wear rate and particle size on the tested materials is

discussed. Factors, which should be considered in wear modeling and prediction, have also been

addressed. They have studied that larger solids particles resulted in higher mass loss in all test

materials. Although the wear rates at smaller particle sizes were relatively close within each

material group, the wear rate difference was significantly widened with larger particle sizes.

G. Desale et al27 [2005] have studied the improvement in the design of pot tester to simulate

erosion wear due to solid-liquid mixute. The have minimized the effect of relative velocity

between the wear specimens and solid particles by rotating a PBT propeller in down pumping

mode. They also have made provisions in the test fixtures to evaluate the effect of impact angles,

concentration, velocity etc. on the wear rate.

Feng Jianjun et al28 [2007] have conducted numerical simulations on impeller diffuser

interactions in radial diffuser pumps to investigate the unsteady flow, and more attention is paid

to pressure fluctuations on the blade and vane surfaces Computational results show that a jet-

wake flow structure is observed at the impeller outlet. The biggest pressure fluctuation on the

blade is found to occur at the impeller trailing edge, on the pressure side near the impeller


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trailing edge, and at the diffuser vane leading edge, independent of the flow rate, radial gap, and

blade number configuration. All of the flow rate, blade number configuration, and radial gap

influence significantly the pressure fluctuation and associated unsteady effects in the diffuser

pump.

Gandhi B.K. et al29 [2007] observed that the wear at normal impact condition is a strong

function of hardness hardness ratio of erodent and target materials. He carried out experiment for

different solid concentrations, particle sizes and velocities. Based on experimental data, he has

proposed a correlation to predict the erosion wear at normal impact conditions.

Experiments have been carried out using a slurry pot tester by orienting the wear specimen

normal to their rotational direction. Erosion wear due to normal impact has strong dependence on

velocity and particle size but relatively weak dependence on solid concentration. SEM

micrographs and surface roughness measurement of worn out surface reveals that the penetration

by solid particles at the target material surface is a function of hardness ratio.

Williams A. John et al30 [2007]proposed that when material is lost from loaded surface either

entirely or principally through some form of mechanical interaction the concentration, size and

shape of the debris particles carry important information about the state of the surfaces from

which they were generated and thus, by implication, the potential life of the contact and of the

equipment of which this forms part. To use debris examination as a diagnostic aid in assessing

health of the operating plant, which may contain many tri biological contacts, requires not only

careful and standardized procedures for debris extraction and observation but also an

appreciation of the mechanism by which wear occurs and the regimes in which each of the

contacts of interests operates when displayed on an appropriate operational map.

Ridgway N.et al31 [2009] emphasizes that non uniform packing compression is not the sole

contributor to gland seal life cycle cost and reliability, an improved scientific understanding of

tribological wear process is required for existing designs. In slurry service particle size

distribution, shape and relative hardness with the shaft sleeve are expected to influence the useful

life of shaft sleeve and packing. They identified the key variables in the development of wear

equation within the framework of contact mechanism and inorganic structural chemistry. Particle

properties including size, relative hardness and fracture toughness were found to be of vital

importance. The specific wear rate was found to be dependent on particle size.


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Wang Yao et al32 [2009] has proposed design of an experimental system for assessing wear

conditions of slurry pumps. This experimental system is intended to provide data for both simple

and advanced data analysis of the correlation between the wear status of wetted components and

a number of parameters. This experimental system is a test loop which contains a slurry pump

and data acquisition system among other components. Test runs at different rotating speeds with

controlled particle proportion and slurry temperatures. It is designed primarily to provide good

scalability with regards to field conditions and satisfactory accuracy for subsequent analysis.

Wu Yulin et al33 [2009] have measured the internal flow field in a centrifugal pump working at

the several flow conditions using the particle image velocimetry (PIV) technique with the laser

induced fluorescence (LIF) particles and the refractive index matched (RIM) facilities.

The impeller of the centrifugal pump has an outlet diameter in 100mm, and consists of six two-

dimensional curvature backward swept blades of constant thickness. Measured results give

reliable flow patterns in the pump. It is obvious that application of LIF particle and RIM are the

key methods to obtain the right PIV measured results in pump internal flow.

Suzuki Masaya et al34 [2009] Erosion phenomenon, including the temporal change of the flow

field and the wall shape. They have simulated sand erosion of a 90 degrees bend with a square

cross-section. The numerical results are compared with experimental data and it is confirmed that

the developed code can capture the sand erosion phenomenon reasonably.

L. Pullum et al35 [2009] have studied the effect of varying impeller geometrical parameters on

the turbulent velocity fields in mixing tanks. They have used pitched blade turbines and disc

turbines and measurements have been taken through laser doppler velocimetry (LDV) technique.

They have evaluated the flow number correlations based on power number in their investigation.

Achebo I. Joseph36 [2009] have used drift flux models based on Eulerian continuum equations

in predicting erosion wear rate in a transmission pipeline. In this case, a pipeline with a diameter

of 0.5m was investigated. It was found that there was a large sand particle concentration on the

welded parts of the pipe which has affected the internal geometry of the pipe. From physical

examination, the reduction in the nominal thickness of the pipe was related to erosion wear.

Sanna Haavisto et al37 [2009] have studied the particle velocity and concentration profiles of

sand-water slurry in a stir tank. Three dimensional velocity profiles were measured utilizing

ultrasound Doppler velocimetry along lines located circumferentially between two baffles of the

tank. The volume fraction of the solid phase investigated by them was 5% and 10%.


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They have conducted CFD studies of slurry flow with algebraic slip mixture model and full

Eulerian multiphase model. Standard k- model was applied in turbulence modelling. The

agreement between the simulated and the measured particle velocities was found to be relatively

good in the central region of the vessel. Near the wall, deviation of the results was observed with

increasing solid concentration. Eulerian multiphase model was tested with parameters

corresponding closely to those used with algebraic slip mixture model. Results obtained with it

deviated from measurements more than mixture model predictions.

K. Mohanarangam et al38 [2009] have studied CFD modelling of floating and settling phases

in settling tanks. A Computational Fluid Dynamics (CFD) model for modelling a floating phase

has been developed and tested on a settling tank. The model used by them for settling tanks was

able to predict the settling of solids and the formation of a higher density layer of solids at the

bottom of the vessel.The simulations were performed by customizing the software ANSYS-CFX

.O. Khazam et al39 [2009] have conducted study on the drawndown of the floating solids in

stirred tanks. In this study they have reported the effect of the type of impeller, impeller

submergence, and baffle configuration on the minimum draw down speed (Njs) are reported.

They have compared the drawdown of floating solids for a range of baffle geometries in order to

determine the most efficient design strategy.

Figure 9: Manufacturing Process Behaviour


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CHAPTER 4

PRODUCTION AND MANUFECTURING PROCESS AND

SUPPORT


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The production system is the collection of people, equipment, and procedures, organized to

accomplish the manufacturing operations of a company (or other organization).Production

systems can be divided into two categories or levels as indicated in Figure 10:

Production System

Figure 10: The production system consists of facilities and manufacturing support systems.

1. Facilities. The facilities of the production system consist of the factory, the equipment in the

factory, and the way the equipment is organized.

2. Manufacturing support systems. This is the set of procedures used by the company to manage

production and to solve the technical and logistics problems encountered in ordering materials,

moving work through the factory, and ensuring that products meet quality standards. Product

design and certain business functions are included among the manufacturing support systems.

In modern manufacturing operations, portions of the production system are automated and/or

computerized. However, production systems include people. People make these systems work. In

general, direct labour people (blue collar workers)are responsible for operating the facilities, and

professional staff people (white collar workers) are response able for the manufacturing support

systems.

Manufacturing

Facilities:

Factory


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4.1 Production System Facilities

The facilities in the production system are the factory, production machines and tooling, material

handling equipment, inspection equipment, and the computer systems that control the

manufacturing operations. Facilities also include the plant layout, which is the way the

equipment is physically arranged in the factory. The equipment is usually arranged into logical

groupings, and we refer to these equipment arrangements and the workers who operate them as

the manufacturing systems in the factory. Manufacturing systems can be individual work cells,

consisting of a single production machine and worker assigned to that machine. We more

commonly think of manufacturing systems as groups of machines and workers, for example, a

production line. The manufacturing systems come in direct physical contact with the parts and/or

assemblies being made. They touch the product.

A manufacturing company attempts to organize its facilities in the most efficient way to serve

the particular mission of that plant. Over the years, certain types of production facilities have

come to be recognized as the most appropriate way to organize for a given type of

manufacturing.

4.2 Low Quantity Production

The type of production facility usually associated with the quantity range of 1 to 100 units/year is

the job shop, which makes low quantities of specialized and customized products. The products

are typically complex, such as space capsules, aircraft, and special machinery. Job shop

production can also include fabricating the component parts for the products. Customer orders

for these kinds of items are often special, and repeat orders may never occur. Equipment in a job

shop is general purpose and the labour force is highly skilled.


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Figure 11: Various types of plant layout: (a) fixed-position layout, (b) process layout,(c)

cellular layout, and (d) product layout.


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Are routed through the departments in the particular order needed for their processing, usually in

batches. The process layout is noted for its flexibility; it can accommodate a great variety of

alternative operation sequences for different part configurations. Its disadvantage is that the

machinery and methods to produce a part are not designed for high efficiency. Much material

handling is required to move parts between departments, so in-process inventory can be high.

4.3 Medium Quantity Production

In the medium quantity range (10010,000 units annually), we distinguish between two different

types of facility, depending on product variety. When product variety is hard, the traditional

approach is batch production, in which a batch of one product is made, after which the facility is

changed over to produce a batch of the next product, and so on. Orders for each product are

frequently repeated. The production rate of the equipment is greater than the demand rate for any

single product type, and so the same equipment can be shared among multiple products. The

changeover between production runs takes time.

Called the setup time or changeover time, it is the time to change tooling and to set up and

reprogram the machinery. This is lost production time, which is a disadvantage of batch

manufacturing. Batch production is commonly used in make-to-stock situations, in which items

are manufactured to replenish inventory that has been gradually depleted by demand. The

equipment is usually arranged in a process layout.

An alternative approach to medium range production is possible if product variety is soft. In this

case, extensive changeovers between one product style and the next may not be required. It is

often possible to configure the equipment so that groups of similar parts or products can be made

on the same equipment without significant lost time for change overs. The processing or

assembly of different parts or products is accomplished in cells consisting of several

workstations or machines.

4.4 High Production

The high quantity range (10,000 to millions of units per year) is often referred to as mass

production. The situation is characterized by a high demand rate for the product, and the


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production facility is dedicated to the manufacture of that product. Two categories of mass

production can be distinguished: (1) quantity production and (2) flow line production.

Quantity production involves the mass production of single parts on single pieces of equipment.

The method of production typically involves standard machines (such as stamping presses)

equipped with special tooling (e.g., dies and material handling devices), in effect dedicating the

equipment to the production of one part type. The typical layout used in quantity production is

the process layout.

Flow line production involves multiple workstations arranged in sequence, and the parts or

assemblies are physically moved through the sequence to complete the product.

The workstations consist of production machines and/or workers equipped with specialized tools.

The collection of stations is designed specifically for the product to maximize efficiency. The

layout is called a product layout, and the workstations are arranged into one long line, or into a

series of connected line segments. The work is usually moved between stations by powered

conveyor. At each station, a small amount of the total work is completed on each unit of product.

Figure 12: Types of facilities and layouts used for different levels of production quantity

and product variety.

4.5 Manufacturing Support System

To operate the production facilities efficiently, a company must organize itself to design the

processes and equipment, plan and control the production orders, and satisfy product quality


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requirements. These functions are accomplished by manufacturing support systems people and

procedures by which a company manages its production operations. Most of these support

systems do not directly contact the product, but they plan and control its progress through the

factory.

Manufacturing support involves a cycle of information-processing activities, as illustrated in

Figure

The information-processing cycle, represented by the outer ring, can be described as consisting

of four functions :(1) business functions,(2) product design, (3) manufacturing planning, and (4)

manufacturing control.

Business Functions: The business functions are the principal means of communicating with the

customer. They are therefore, the beginning and the end of the information-processing cycle.

Included in this category are sales and marketing, sales forecasting, order entry, cost accounting,

and customer billing.

The order to produce a product typically originates from the customer and proceeds into the

company through the sales and marketing department of the firm. The production order will be in

one of the following forms:(1) an order to manufacture an item to the customers

specifications,(2) a customer order to buy one or more of the manufacturers proprietary

products, or (3) an internal company order based on a forecast of future demand for a proprietary

product.

Product Design: If the product is to be manufactured to customer design, the design will have

been provided by the customer. The manufacturers product design department will not be

involved. If the product is to be produced to customer specifications, the manufacturers product

design department may be contracted to do the design work for the product as well as to

manufacture it.


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Figure 13: The information processing cycle in a typical manufacturing firm.

Manufacturing Planning: The information and documentation that constitute the product

design flows into the manufacturing planning function. The information-processing activities in

manufacturing planning include process planning, master scheduling, requirements planning, and

capacity planning. Process planning consists of determining the sequence of individualprocessing and assembly operations needed to produce the part. The manufacturing engineering

and industrial engineering departments are responsible for planning the processes and related

technical details.

Manufacturing Control: Manufacturing control is concerned with managing and controlling the

physical operations in the factory to implement the manufacturing plans.

The flow of information is from planning to control as indicated in Figure 1.5.Information also

flows back and forth between manufacturing control and the factory operations. Included in the

manufacturing control function are shop floor control, inventory control, and quality control.

Shop floor control deals with the problem of monitoring the progress of the product as it is being

processed, assembled, moved, and inspected in the factory. Shop floor control is concerned with


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inventory in the sense that the materials being processed in the factory are work-in-process

inventory. Thus, shop floor control and inventory control overlap to some extent. Inventory

control attempts to strike a proper balance between the danger of too little inventory (with

possible stock-outs of materials) and the carrying cost of too much inventory. It deals with such

issues as deciding the right quantities of materials to order and when to reorder a given item

when stock is low.

The mission of quality control is to ensure that the quality of the product and its components

meet the standards specified by the product designer. To accomplish its mission, quality control

depends on inspection activities performed in the factory at various times during the manufacture

of the product. Also,raw materials and component parts from outside sources are sometimes

inspected when they are received, and final inspection and testing of the finished product is

performed to ensure functional quality and appearance.

4.6 Advance Manufacturing

Historically, manufacturing organizations made improvements in their productions processes

primarily through investments in physical capital. Advices in mechanization, for example,

enabled manufacturing firms to enhance efficiency in production while actually lowering the

required skills and capabilities of employees. As a result, many firms actually took the tactic of

deskilling their workforces to reduce labor expenses, thereby diminishing the necessary level of

investments in human capital with the hope of increasing profits.

In contrast to this perspective, advocates of the cotemporary manufacturing paradigm argue for a

dramatically different orientation toward employees. These post-industrial theorists propose that

compared to the deskilling tactics of traditional manufacturing, more advanced systems require a

set of complementary practices for upskilling the workforce. Indeed, some studies have

suggested that modern manufacturing systems demand more enhanced technical, conceptual,

analytic and problem solving skills than typically were required in traditional manufacturing

environments.

In the manufacturing sector, the new technological advances have revolved around machine tools

and equipment. Advances in automation of machine tools began about 30 years ago with the first

generation of programmable machine tools-the numerical controlled machine tools (NC). The


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NC did not become widely used until the 1970s. The second generation, computerized numerical

control machine (CNC), was introduced in the late 1970s. These new machine tools have the

capacity to produce the high volume standardized parts and products necessary for competitive

success in undifferentiated markets.

The first AMT technologies were introduced in the 1950s, but it was not until the 1970s that the

adoption of AMTs took off and the 1980s that their use became widespread. Today, nearly all

currently produced manufacturing equipment incorporates some electronics element and thus fits

the definitions for AMTs.

There are three types of manufacturing systems: crafts shops; dedicated manufacturing systems

(DMS); and advanced manufacturing technologybased systems (AMT). Their research is based

on Teece conceptualization of long-linked versus intensive technologies. Using their

classification scheme, DMS are considered long-linked industrial systems employing hard

automation whereas AMT are post-industrial enterprises employing flexible resources.

There are many distinctions between craft shops and DMS. While craft shops employ skilled

artisans who use various hand tools, DMS deploy special-purpose machinery operated by

unskilled manual laborers. In a craft shop, workers are orga

optimization and automation of production process at roop polymers ltd through project management

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