INTEGRATION OF THE DESIGN AND MANUFACTUREHIGH-PRECISION CAST COMPONENTS

by

NORMAN CORNELIUS CLAMPITT III

Bachelor of Science in Mechanical Engineering, Purdue University 1997

OF

Submitted to the Department of Mechanical Engineering and the Sloan School of Management in partialfulfillment of the requirements for the degrees of

Master of Science in Mechanical Engineering and Master of Science in Management

In conjunction with the Leaders for Manufacturing Program at theMassachusetts Institute of Technology

June, 2000

2000 Massachusetts Institute of Technology.

All rights reserved.

Signature of Author

Certified by

Certified by

Accepted b

Accepted b

Department of Mechanical EngineeringSloan School of Management

May 5, 2000

zDafiiel Whitney, Thesis SupervisorSenior Research Scientist, Center for Technology, Policy and Industrial Development

Roy Welsch, Thesis SupervisorProfessor of Statistics and Management

Professor Ain A. Sonin, Chairman of the Graduate CommitteeDepartment of Mechanical Engineering

yMargaretAndrfws, Executive Director of the Masters Program

Sloan School of Management

MASSACHUSETTS INSTITUTEOF TECHNOLOGY

SEP 2 0 2000

LIBRARIES

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ABSTRACT

For canptitw prduct dewop ment, the design omganization ofa mamzactrng cnpy requis k nodaige of thesuppliers'manufactumingpnesses and ofprnaples ofdesignfor mnfacurahility. This knoud& nust he coll&a,store, made accessible, and actiny utilizi. A ll of these knokdcge managemnt activies are ctical to the sucassfulrealization ofthelue of this knodaige.

The purpose of the desis is to illustrate the imran ofmanagig knodaige in a supply camn and to enmendzuys to inpmw knodedge managmmt The illustrations are drawnflrm a sezwn-maih intemship pnpt sponsom&by A BB A L S TOM POWER, a manufactuer ofpomer generation equipmet and a partner ofthe Leadersfor

Manufacturingpgram at the Massadusetts Institute of Tendokg

The purpose of the pmt us to ident ays to build a knouWage base ofprmples and ridesfor impvving demanufacurahility ofpnuca designs, therby rnducing cost, tme-to-market, and nanrformanx. The intent uas toinpvw the mn c rm men of the design oganization, reducing the depodoze upon a single supplier bygivig it the poer to design parts to he manufacturable so that Axy amld be made by many suppliers. The result aus aset of newrmndatins for in7 ing pnluat deW/opMt and the effectiawess of knoalge managmnt in conanmmtennering.

The focus of th projctus e praision cast turbine canponmts of dx A BB A L S TOM POWER heavy duty gasturbie engines. Each of dxse conpnaits wdeyges a series of pratins, often perfonral by difeent supplie.These parts repmsent a signficant tmhnical challmge to dx design team.

Thrugh an analysis of quality data and inteviewsz ith designer and suppliers, a set ofmnmendatims zus made tothe canpzyfor impovg the design oiganizatin's manufacturing knowa/ge base. There am opportimiiesforimpoving thefeedickfian manufturmg by idnwvg all supplien ofa part early in its design and by motiwting

suppliers to make acurate and on-time deliwnes. A nwner of obsertions uure made uhi should he includa insuch a knowage base. Many of the tos afmmtly used by dx design teanformanagmgfield experenx know/a/gecan he adaptai to use in managmg kndge gainafiraniufacturingexpere . T here ar opportuniies toenhane dxse toos to make dm nw acessible and effati. 7here are also appotwnities to comwrt lessons leamedinto design rides and to incoporate these into design softure. Many of dese arimmndatioms mquire inwstment ofresountes. This inustmet can he just fud fthe result is awdiing the need to re/eam past lessons.

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ACKNOWLEDGEMENTS

First I wish to thank my Lord and Savior Jesus Christ, through whom all things are possible. I thank my

family and friends who prayed for me during my two years at MiT. I especially wish to thank my best friend

Zhelinrentice Scott for her love and support throughout this project.

I wish to acknowledge the Leaders for Manufacturing Program for its support of this work through its

resources and support of this project..

I also wish to thank my advisors Daniel Whitney and Roy Welsch for their guidance.

I thankfully acknowledge the people at ABB ALSTOM POWER and its suppliers who made it possible for

me to learn about their processes and to collect the necessary information which forms the basis of this

thesis. I hope that this thesis project provides a valuable contribution to the company. In particular, I wish

to thank Prith Harasgama, Erhard Kreis, Alastair Clark, Miriam Park, Stephen Howarth, Christoph Nagler,Mark Richter, Christof Pfeiffer, Alex Beeck, Tim Strauss, Stefan Florjandi, Ernst Pauli, Nick Jovic, Bernard

Robic, Diethelm Boese, Ivan Dim, Gordon Anderson, Markus Oehl, Martin Meyer ter Vehn, Stephen Bowes,Klaus Schneider, Edi Primoschitz, Gary Dewis, Mark Baker, Dean Westerman, and Dan Tasker.

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TABLE OF CONTENTS

AB STRA C T ................................................................................................................................................................ 3

SEC TIO N 1: O V ER V IEW ...................................................................................................................................... 13

1.1 INTRODUCTION .................................................................................................................................................. 13

1.2 PROBLEM STATEM ENT ....................................................................................................................................... 131.3 THESIS OBJECTIVES ........................................................................................................................................... 131.4 PROJECT OBJECTIVES ........................................................................................................................................ 131.5 A READER'S GUIDE TO THE THESIS .................................................................................................................... 151.6 SUM M ARY ......................................................................................................................................................... 16

SEC TIO N 2: BA CK G R O U N D ................................................................................................................................ 17

2.1 INTRODUCTION .................................................................................................................................................. 172.2 A BB A LSTO M PO W ER ................................................................................................................................. 172.3 GAS TURBINES - TECHNICAL CHALLENGES ....................................................................................................... 172.4 THE PRECISION CAST PARTS SUPPLY CHAIN ....................................................................................................... 182.5 IGT INDUSTRY ANALYSIS ................................................................................................................................. 19

Competition - Strong ......................................................................................................................................... 20Blade and vane suppliers - Strong ..................................................................................................................... 20

Custom ers - Strong ............................................................................................................................................ 20

Potential Entrants- W eak ................................................................................................................................... 20

Substitutes - W eak ............................................................................................................................................. 21

Implications ........................................................................................................................................................ 21

2.6 THE G T24/26 GAS TURBINE .............................................................................................................................. 21

2.7 THE PRODUCT DEVELOPM ENT PROCESS ............................. ................................................................................ 21

2.8 BENCHM ARKING CONCURRENT ENGINEERING .................................................................................................. 21

2.9 PRIOR PROJECT W ORK ........................................................................................................................................ 22

2. 10 BACKGROUND LITERATURE ............................................................................................................................ 232.11 SUM M ARY ....................................................................................................................................................... 23

SECTION 3: THE BUSINESS CASE FOR IMPROVING FEEDBACK AND ORGANIZATIONALLEA RN IN G ............................................................................................................................................................... 24

3.1 INTRODUCTION .................................................................................................................................................. 24

3.2 A M ODEL OF D IM LEARNING ........................................................................................................................... 24

3.3 SUM M ARY ......................................................................................................................................................... 26

SEC TIO N 4: A C C O UN T O F TH E PR O JECT ..................................................................................................... 27

4.1 INTRODUCTION .................................................................................................................................................. 274.2 N ONCONFORM ANCE REPORT (N CR) ANALYSIS ................................................................................................ 27

W hat N CRs tell ................................................................................................................................................... 27W hat they don't tell ............................................................................................................................................ 28

4.3 INTERVIEW S W ITH DESIGNERS ........................................................................................................................... 284.4 INTERVIEW S W ITH SUPPLIERS ............................................................................................................................ 284.5 SUM M ARY ......................................................................................................................................................... 28

SECTION 5: RECOMMENDATIONS FOR DEALING WITH SUPPLIERS IN DEVELOPMENT ............. 30

5.1 INTRODUCTION .................................................................................................................................................. 30

5.2 COMM IT TO A CAPABLE SUPPLIER EARLY .......................................................................................................... 30C h a lle n g es ......................................................................................................................................................... 3 0

5.3 INVOLVE ENTIRE CHAIN IN CONCEPT PHASE ...................................................................................................... 31Example: Vane I Hook Feature ......................................................................................................................... 31Other Examples .................................................................................................................................................. 32Challenges ......................................................................................................................................................... 32

5.4 ALIGN INCENTIVES ............................................................................................................................................ 32Paym ent based on quality .................................................................................................................................. 32Limited NC acceptance period with regular intermediate milestones ............................................................... 32Establish a regular delivery schedule ................................................................................................................ 33Encourage accurate comm itm ents ..................................................................................................................... 33Challenges ......................................................................................................................................................... 33

5.5 SUMMARY ......................................................................................................................................................... 33

SECTION 6: RECOMMENDATIONS FOR DESIGNING PARTS ................................................................... 35

6.1 INTRODUCTION .................................................................................................................................................. 35C h a llen g es ......................................................................................................................................................... 3 7

6.2 M AKE COOLING CHANNELS ACCESSIBLE ........................................................................................................... 38Challenges ......................................................................................................................................................... 39

6.3 PROVIDE FOR SLAVE DATUM FEATURES ........................................................................................................... 406.4 PROJECT PLANNING INTEGRATION ..................................................................................................................... 40

C h a llen g es ......................................................................................................................................................... 4 16.5 UNDERSTAND IMPACT OF DECISIONS AND CHANGES ON THROUGHPUT TIME, COST AND QUALITY .................... 41

C h a llen g es ......................................................................................................................................................... 4 26.6 KEEP MANUFACTURER INFORMED EARLY ABOUT POSSIBLE CHANGES ............................................................... 42

Challenges ......................................................................................................................................................... 446.7 ACTIVELY INCORPORATE MANUFACTURING FEEDBACK .................................................................................... 446.8 SUMMARY ......................................................................................................................................................... 44

SECTION 7: RECOMMENDATIONS FOR LEARNING FROM EXPERIENCE (FEEDBACK TODESIG N) .................................................................................................................................................................... 46

7.1 INTRODUCTION .................................................................................................................................................. 467.2 SUPPLIER VISITS ................................................................................................................................................ 46

Challenges ......................................................................................................................................................... 467.3 ANALYSIS OF QUALITY DATA ............................................................................................................................ 47

N C R .................................................................................................................................................................... 4 7N CR Serial Number Traceability ....................................................................................................................... 47N CRF4PS, Knowledge-based system ................................................................................................................ 47Challenges ......................................................................................................................................................... 48

7.4 PRODUCT SUPPORT TOOLS ................................................................................................................................ 48Experience Response System .............................................................................................................................. 48Problem H istory Files ........................................................................................................................................ 48Project status and communication files ............................................................................................................. 48Case Studies ....................................................................................................................................................... 48Challenges ......................................................................................................................................................... 49

7.5 INTRANET .......................................................................................................................................................... 49Challenges ......................................................................................................................................................... 49

7.6 STON ERULEO .................................................................................................................................................. 49Automate 2D D rawing Generation .................................................................................................................... 49Incorporate Feedback into Mfg ......................................................................................................................... 50Challenges ......................................................................................................................................................... 50

7.7 SUMMARY ......................................................................................................................................................... 50

SECTION 8: CO N CLUSIO NS ................................................................................................................................ 51

8.1 INTRODUCTION .................................................................................................................................................. 51

8.2 D EALING W ITH SUPPLIERS....................................................................... ..... .... ... - - - - - --............................. 51

8.3 D ESIGN IN G PA RTS ...................................................................................... ... ................................................ 51

8.4 LEARNING FROM EXPERIENCE........................................................................................... ... -......................... 51

8.5 O PPORTUNITIES FOR FUTURE W ORK........................................................................... . ---.. ....................... 51

REFERENCES ................................................................................................................................---..............--- -- - 53

APPENDIX A: CONCURRENT ENGINEERING PROCESS ............................................................................ 54

APPENDIX B: RELEVANT LITERATURE ........................................................................................................ 57

D F M .............................................................................--. ............ . ----..-...-. ---. ----........................................... 57

MANUFACTURING TECHNOLOGIES .......................................................................... .............----............... 57

SUPPLY CHAIN M A NAGEM ENT ..................................................................................... ........... -----....................... 57

ORGANIZATIONAL LEARNING ................................................................................................................................. 58

APPENDIX C: CAUSAL LOOP DIAGRAMS...................................................................................................... 60

APPENDIX D: A MODEL OF DFM LEARNING AND ITS COST IMPLICATIONS ................. 61

M OD EL FORM U LATION ......................................................................................................... . ---------------........... 61

APPENDIX E: MACHINING COST ESTIMATION MODELS ........................................................................ 76

LASER D RILLING .................................................................................... ... .........----------...................................... 76ELECTRIC D ISCHARGE M ACHINING....................................................................................................................... 76

ELECTRO-CHEM ICAL M ACHINING............................................................................. .... -------.---- .--------- . 77

APPENDIX F: OVERLAPPING OPTIMIZATION MODEL ............................................................................. 78

APPENDIX G: DEFINITIONS.....................................................................................................------............ 79

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LIST OF FIGURES

Figure 1 The concurrent engineering process......................................................................... ......14

Figure 2 Concurrent engineering with feedback to a knowledge base ...................................................... 15

Figure 3 Partial assembly tree showing the role of precision cast parts in a power plant.......................... 19

Figure 4 A supply chain map for a typical precision cast part showing material flow. ............................. 19

Figure 5 A causal loop diagram of the DFM learning process. ................................................................ 25

Figure 6 The learning process and associated costs. ............................................................................. 26

Figure 7 V ane 1 hook feature ....................................................................................... ...... . .----.... 31

Figure 8 Key Characteristic flowdown for Vane 1 airflow example. ....................................................... 36

Figure 9 Effect of core shift on size of trailing edge cooling air exit holes. ............................................ 37

Figure 10 Cost of solution curves for three basic types of sensitivity analysis......................................... 38

Figure 11 Simplified blade showing cooling air passages and exit holes ................................................. 39

Figure 12 Slave datum feature.................................................................................................................. 40

Figure 13 A simplified financial model of the costs and revenues of a single engine project..................... 42

Figure 14 Recommended overlap strategy given estimates of evolution and sensitivity............................ 43

Figure 15 Types of overlapping and the resulting performance tradeoffs............................................... 44

Figure 16 Concurrent Engineering Timeline.............................................................. ...... 56

Figure 17 Horizontal modular structure vs. vertical integral................................................................... 58

Figure 18 The double helix of oscillation in industry structure and product architecture.......................... 58

Figure 19 The basic components of a causal loop diagram................................................................... 60

Figure 20 Causal loop diagram of complete DFM learning model.............................................................. 61

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SECTION 1: OVERVIEW

1.1 INTRODUCTION

This section explains the aim of the thesis, showing the importance of knowledge management in product

development. Then follows a description of the purpose of the project from which examples are drawn is

also described. The following guide to the thesis explains the structure of the remainder of this document.

1.2 PROBLEM STATEMENT

In manufacturing companies, there is a great deal of opportunity to save money and improve customer

satisfaction through improvements in knowledge management during product development. This is

especially true for companies whose manufacturing is outsourced, but holds for companies in which the

manufacturing organization is internal as well. In order to improve, companies require an understanding of

the problems in knowledge management and potential solutions.

1.3 THESIS OBJECTIVES

The purpose of the thesis is to illustrate the importance of managing knowledge in a supply chain and to

recommend ways to improve knowledge management. The illustrations are drawn from a seven-month

.internship project sponsored by ABB ALSTOM POWER, a partner of the Leaders for Manufacturingprogram at MIT.

1.4 PROJECT OBJECTIVES

The purpose of the project was to identify ways to build a knowledge base of principles and rules for

improving the manufacturability of product designs, thereby reducing cost, time-to-market, and

nonconformance. The intent was to improve the manufacturing competence of the design organization,reducing the dependence upon a single supplier by giving it the power to design parts to be manufacturable

so that they could be made by many suppliers.

Concurrent engineering is the simultaneous development of a product and the manufacturing process used to

produce it.1 This process shortens the time to market and requires the cooperation of the designer and the

manufacturer. Another intended benefit of cooperation is the improvement of the manufacturability of the

design through feedback from the manufacturer during development, reducing production costs. Figure 1 is

a simplified illustration of this feedback.

1 Note: Fine (1998, 124) builds upon this idea by introducing a third concurrent activity: supply chain design. See Appendix A.

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ConcurrentEngineering

-- ItgertiIeration

Suggestions for DesignManufacturability Specifications

Improvement Manfatuin

Figue 1 The conammt enginering process

The building of a knowledge base of design principles does not eliminate the need for cooperation with

manufacturing in the concurrent process. Rather, the knowledge base strengthens the concurrent process byeliminating redundant feedback. The knowledge base helps the design organization to retain lessons learned

from experience in concurrent development and to avoid going through the process of learning previous

lessons over again.

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DFM DesignRules

ConcurrentEngineering

Iteration

Suggestions for DesignManufacturability Specifications

ImprovementMau ctrn

Figum 2 Conammt engmremg withfeerback to a knouliedge base

Feedback from manufacturing is used to refine the design during development. The addition of a knowledgebase in Figure 2 increases the effectiveness of the process by retaining experience and eliminating the need tore-learn old lessons through new experience feedback. Such a knowledge base exists in any concurrentengineering effort in which the people involved have prior experience. The recommendations in this report

are not meant to replace the knowledge and experience of the people involved, but to support them and to

improve the degree to which this knowledge is shared throughout the design organization.

1.5 A READER'S GUIDE TO THE THESIS

The rest of this thesis is organized as follows:

Section 2 gives the necessary background information to put the analysis and conclusions in proper context.

The Company's history and current state of affairs are presented in a brief form, as relevant to the project.

The industry of interest is analyzed from the perspective of the Company. A description of the product of

interest and a brief history of its development are included to support the following sections. The original

project upon which this project was based is described to cover prior related work done at the company.

Section 3 builds the business case for improving knowledge management. A simple model of the systemdynamics of learning from experience is used to show the cost impact of learning capabilities.

Section 4 describes the project itself, how the information was collected and what was discovered.

Section 5 recommends ways to improve the way the company works with suppliers in concurrent engineeringand foreseen challenges in the implementation of these recommendations.

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Section 6 suggests ways to improve the way parts are designed to reduce their cost, throughput time anddefect rate.

Section 7 recommends ways to improve knowledge management in product development. Tools aredescribed that will allow knowledge to more effectively be captured, organized, accessed, and used in futuredevelopment projects.

Section 8 draws general conclusions from the specific lessons learned in the process of making the precedingrecommendations.

A literature review, machining cost estimation models, and table of definitions are included as appendices toclarify references within the text with more detail.

1.6 SUMMARY

This thesis will illustrate the importance of knowledge management to product development throughexamples observed during the internship project at ABB ALSTOM POWER The remainder of the reportwill establish the framework and context, motivate the need for improved organizational learning,recommend ways to improve the design process and learning processes, and draw conclusions for the generalcase.

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SECTION 2: BACKGROUND

2.1 INTRODUCTION

The following background information explains the context of the project from which examples are drawn.A brief history of the sponsoring company is followed by a description of the product of interest and thesupply chain that produces the components that will be the focus of the thesis. An analysis of the state of theindustry explains the relative strength of the different players whose interests are at stake. A history of thedesign itself leads into the product development process and a comparison of the state of concurrentengineering within the company with that of its competitors. A description of the preceding project places theproject of interest in its proper context. The section concludes with a reference to relevant literature and abrief summary of the background.

2.2 ABB ALSTOM POWER

In 1987, ASEA AB of Vdsteris, Sweden, and Brown Boveri Ltd. of Baden, Switzerland, announced plans tomerge and form Asea Brown Boveri Ltd. (ABB), headquartered in Zurich, Switzerland. The technical leadcenter for Power Generation remained in Baden. Over the next few years, ABB made a series of acquisitions,joint ventures, and divestitures. Just prior to the joint venture described below, ABB consisted of thefollowing businesses:

Power Generation

Power Transmission

Power Distribution

Automation

Oil, Gas and Petrochemicals

Building Technologies

Financial Services

On March 23, 1999, ABB and ALSTOM formed ABB ALSTOM POWER, a 50-50 joint venture consistingof ABB Power Generation (Excluding Nuclear) and ALSTOM Energy (Excluding Heavy Duty GasTurbines), employing 58,000 people in over 100 countries. As the formation of the joint venture did little toaffect ABB's gas turbine product line, which is the focus of this thesis and project, the ALSTOM backgroundis not included here. Furthermore in April 2000 Alstom acquired the remaining share (50%) from ABB andthe present company is designated Alstom Power, a wholly owned subsidiary of Alstom. Hereafter the termused is AAP.

2.3 GAS TURBINES - TECHNICAL CHALLENGES

Gas turbines are heat engines used to power jet aircraft and electric generators, among other things.Industrial gas turbines (IGTs) used to drive electric power plants are attractive to power producers because oftheir efficiency and the fact that some are fueled by natural gas, some by fuel oil, and some by eitherinterchangeably. Energy can be recovered from the exhaust gases to generate steam and power steamturbines in what is called a "combined cycle" power plant. Combined-cyde plants achieve up to 60% fuelefficiency. The basic principle behind gas turbines involves a compressor, a combustion chamber, and one or

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more turbines. Both the compressor and each turbine are rotating stages of airfoils. The compressor drawsin air and compresses it to the proper inlet pressure and temperature for combustion. Fuel, mixed with air, isburned in the combustion area. The expanding hot gas drives each turbine, which drives the compressorand/or the load, which is a generator in the case of an electric power plant. The frequency of the powergenerated is determined by the rotating speed of the engine. Some markets use 60-hertz power (e.g. NorthAmerica), while others use 50-hertz (e.g. Europe and Asia).

Over time IGT customers demand higher efficiency, while environmental regulations require lower NOxemissions. Both of these requirements are met by increasing combustion temperatures. However, this beginsto stretch the limits of durability of the engine components, particularly the burners, heat shields, and turbineblades (rotating airfoils) and vanes (stationary airfoils).

At one time, turbine blades were machined from forged parts. At that time the company (then BBC) did allthe work in-house. Later, when higher combustion temperatures required parts with substantially highertemperature resistance, turbine blades and vanes were investment cast in high-melting temperature alloys(superalloys). As temperature and stress resistance requirements increased, new technologies were employed.Directionally solidified castings have grain boundaries in only one direction, increasing strength along thataxis. Single crystal parts have no grain boundaries and are the strongest (and most expensive) investmentcastings available. This process is significantly more complex and requires a very high level of technicalexpertise and experience to be found in only a few places in the world. Both AAP and its competitorsdepend upon foundries that specialized in this type of casting.

Even with these exceptional material properties, turbine parts would not survive the hot gas conditionswithout additional cooling, since these temperatures can be above the melting point of the metal. Internalchannels in the parts conduct cooling air, which is diverted from the compressor. Many tiny holes on the hotsurfaces of turbine components allow this air to escape and form a protective film over the parts. Manyturbine components are cast with these internal cooling channels, requiring ceramic cores, an additionaltechnical challenge and expense. For additional protection, many parts are also covered with a ceramiccoating. Although the parts are cast near net shape, some machining operations are still necessary to producemating surfaces and film-cooling holes. The types of materials used require relatively expensive non-traditional machining techniques such as electric discharge machining (EDM), electro-chemical machining(ECM), and laser beam machining (LBM) in addition to the more traditional methods of grinding and milling.

2.4 THE PRECISION CAST PARTS SUPPLY CHAIN

For clarity, Figure 3 shows the basic role of precision cast parts in the end product. These are the parts of theturbine that are designed and manufactured to withstand the hot gas temperatures. The figure contains only aportion of the total number of turbine components. Precision cast parts consist of blades, vanes, burners,and heat shields, among other types. These parts are then assembled into the turbine portion of the housingand rotor of the engine or thermal block. The thermal block is only one piece of an entire power plant.

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Burners

Blades

Vanes PrecisionCast Parts

Shields

Therma

LargeBlocks

Castigs P

GenertorsPower Plant

Structure

Figure 3 Partial assanboy tree shown the role of precsion cast parns ina power plant

Figure 4 illustrates the supply chain of a typical precision cast part. Parts begin life as a casting. Some parts

are equiax castings, while a few are either directionally solidified or single crystal castings. These castings are

then machined to achieve the desired final shape. Many parts are coated for additional protection. Some

machining takes place before coating (Machining I) and some after (Machining II). These processes are

often, but not always, performed by separate manufacturers at geographically dispersed sites.

Casting Machining Coating Machining 10Assembly1 II (ABB)

Figure 4 A supply chain map for a typical precision cast part showing materiaflow.

2.5 IGT INDUSTRY ANALYSIS

The following analysis is based upon Porter's 5 forces framework (Oster 1994, 31). The industry of interest is

the manufacture of industrial gas turbines for use in power generation. This includes producers of both

single- and combined-cycle plants that incorporate gas turbines. This analysis is presented as motivation for

the rest of the thesis and as relevant background information that places the product of interest in its proper

context.

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COMPETITION - STRONG

ABB-ALSTOM POWER is currently third in its share of the GT/CC market, behind the General ElectricCompany (GE) and Siemens-Westinghouse. It distinguishes itself by offering complete power plants inturnkey or "well to wire" packages to customers.

BLADE AND VANE SUPPLIERS - STRONG

Some of the suppliers themselves have a great deal of power. As mentioned earlier, there are very few castingcompanies with the technical expertise and capability to produce the level of technology required by theprecision cast components. IGT make up a smaller portion of their business than aircraft engines. Forexample, a press release from Howmet International, Inc. 2 indicated that 50% of their revenues were fromaircraft (25% new and 25% after-market), while 35% was from IGT. Therefore, the aircraft enginecompanies, including GE, have somewhat more power than AAP in dealing with these suppliers.

This technology is not simple or cheap to develop. The existing experts have the experience of dealing withmany customers, including the relatively large-volume aircraft industry. An IGT manufacturer would find itdifficult, to say the least, to develop this technology in-house. Therefore, IGT manufacturers depend onthese few suppliers.

Howmet, the world's leading supplier for IGTs, is particularly powerful, serving all of the major IGTmanufacturers. Howmet has the unique position of being the leading supplier of directionally solidified andsingle crystal castings. Howmet also has the majority market share in aircraft engine airfoils.

CUSTOMERS - STRONG

IGT customers have traditionally been government-supported utilities. However, in the wake of deregulationan increasing environmental regulation in the electric power industry, there is an increasing number ofindependent power producers (IPP). These IPPs are profit-driven, and somewhat more cost-conscious thanthe former customers are (Schimmoller 1999). They are able to demand guarantees of performance and on-time delivery. Since a late delivery or high fuel cost reduces the net present value of operations, thesecustomers demand price penalties as compensation. Currently, IPPs purchase approximately the samequantity of gas turbine-based power plants (in megawatts) as purchased by utilities.

POTENTIAL ENTRANTS- WEAK

There are several significant barriers to entry. A reliable design requires a great deal of technical expertise andexperience. It also requires an extensive supply chain with a great deal of capacity and experience. There aresmaller firms that have the engineering capability to develop parts of the engine, but lack the manufacturingcapacity. Although these things can be bought, the market share of all remaining manufacturers after the topthree is less than that of AAP,

2 "Howmet Forecast Holds Steady After Boeing Announcement". (January 1, 1999). Online. Internet. Availablehttp://www.howmet.com/corp/news.nsf/(NR+by+Number)/1998-062

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SUBSTITUTES - WEAK

Because of tighter restriction on emissions, power producers are driven to cleaner forms of power generation.At the present time, gas turbines fueled by natural gas are the cleanest form of power generation based on theburning of fossil fuels. Hydroelectric power is, of course, cleaner, but is not available everywhere or insufficient quantities to supply the world's energy demands. Environmental laws are aimed at reducing theamount of nuclear power. Other alternative energy sources such as solar and wind power have yet to proveeconomically feasible. Therefore, there is little threat to the demand for gas turbine power generationequipment.

IMPLICATIONS

The conclusion from this analysis of the gas turbine industry is that one can restrict the focus of any analysisto a struggle between component suppliers, gas turbine customers, and three major equipment producers. Atthe present, there is little gained by including potential entrants or substitute technologies in a model of thesystem. However, among component suppliers, turbine customers and equipment producers, there issufficient competition for value extraction and control of the supply chain to warrant the discussionpresented in this thesis.

2.6 THE GT24/26 GAS TURBINE

By the end of the eighties, BBC had decided to get out of the gas turbine business. A large part of theengineering staff responsible for turbine design was released. After the merger with Asea, the companydecided to keep gas turbines as the focus of the power generation business. To remain competitive, thecompany needed a new gas turbine product, but lacked the engineering knowledge and design capacity todevelop the turbine, an important and technically challenging part of the whole engine described above.Therefore, the company jointly developed the turbine with external contractors, while rebuilding thecapability internally. The two products based on this design were called GT24 (60Hz) and GT26 (50Hz). The50 Hz design is basically the 60 Hz design scaled by a factor of 1.2 The focus of this thesis is the precisioncast turbine components of the upgrade (B version) design.

2.7 THE PRODUCT DEVELOPMENT PROCESS

During the development of a new engine, a set of basic cost and performance targets are transformed intostable, serial production and delivery of complete engines. The basic process begins with the specification ofthese targets. Design teams develop the various major parts of the engine. The design team works with themanufacturing suppliers to develop and validate the production processes. A complete collection ofcomponents for one engine is called an "engine set". Experience gained from engine sets produced duringdevelopment (preserial sets) is used to improve and stabilize the manufacturing processes. The stableproduction processes are reviewed in an Initial Sample Inspection (ISI). This milestone represents the end ofthe product development process and the beginning of serial production. After ISI, the manufacturer hassufficient specification to independently determine whether parts are acceptable. A more detailed explanationof the concurrent engineering process can be found in Appendix A.

2.8 BENCHMARKING CONCURRENT ENGINEERING

Several engineers within the design organization had formerly worked for Pratt and Whitney (Hereafterreferred to as Pratt). They were able to comment on their perceptions of the differences between concurrentengineering at AAP and at Pratt. Based on their impressions it seems that there is somewhat lesscommunication between the designers and the manufacturers at AAP than at Pratt. At AAP, theieis moreresistance to choosing a supplier early, mostly from the supply chain management organization, not fromdesign. There is a significantly higher level of education among AAP engineers, but somewhat less

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experience. A former Pratt employee commented that both organizations were understaffed, but AAP wa;more so. At AAP component owners are responsible for a set of parts from the concept phase through serialproduction. At Pratt, this function is divided among design engineers and project engineers, who areresponsible for parts in production. Another former Pratt engineer found it difficult at first to work in theAAP environment, suggesting that the new employee training was not as good as that of Pratt. Someindividual engineering managers, however, make the effort to look after new engineers, pairing them withmentors until they are ready to work independently. This method, though not a standard company-widepractice, has the added benefit of helping to maintain and distribute the organization's knowledge andexperience by sharing it with new members. More than one former Pratt engineer noted AAP's strength indocumentation, which seemed to take up a larger part of an engineer's time at AAP than at Pratt, though oneperson questioned its effectiveness. Culturally, one engineer observed that one had to be more aggressive atAAP to get things done, but that people were receptive to ideas for improvement.

2.9 PRIOR PROJECT WORK

Prior to the start of this project, a similar effort was focused on integrating the design and manufacture oflarge castings, mainly casings. These castings, usually one per engine and weighing several tons each, werestudied to find common problems in manufacture that could be reduced or eliminated by changes in design.An analysis of Nonconformance Reports (NCR) led to the identification of problematic features in thecastings.

A Nonconformance Report is a type of quality documentation that allows the issuing organization (supplier)to report parts that do not conform to the specification. The customer (AAP) can then give an engineeringdisposition for the parts. The parts can then receive one of the following dispositions:

accept without modification

accept and identify for special future treatment

rework

scrap

The NCR system streamlines this process by handling the information electronically and keeping a record ofthe incident.

The locations of casting defects were gathered from the NCRs and summarized in a 2-D histogram. Thisshowed the areas that caused the most defects. This information was useful to the casting supplier inadjusting the design of their tooling in order to reduce the amount of defects and, consequently, the time andcost required to produce a casting.

The initial focus of this project was to conduct a similar analysis on precision cast parts (i.e. blades, vanes,burners, heat shields, etc.). It soon became clear, however, that a sufficient quantity of data of the typeanalyzed for large castings did not exist in the NCR records for precision castings. The improvementsrealized in the large casting project were possible because the factory recorded a great deal of casting defectdata in the NCRs, but did not know what the trends were in the defect locations. Once this was pointed outto them, they were able to make corrections. As described below, such casting defect data and other localizeddefect data was scarce among NCRs of precision cast parts, requiring further investigation.

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2.10 BACKGROUND LITERATURE

A description of relevant existing work can be found in Appendix B. All of the principles mentioned in thisthesis upon which the recommendations were based are illustrated by examples observed during the project.However, many of these same principles can be found in the literature. The same was true of the priorproject involving large castings. This helps to illustrate the importance of managing knowledge within thedesign organization and across the supply chain, as discussed later.

2.11 SUMMARY

The rest of the thesis focuses on the precision cast turbine components of ABB ALSTOM POWER's GT24and GT26 engines. These components represent a major technical challenge requiring a great deal ofexpertise to achieve both performance and reliability. The company faced a major challenge when it decidedto compete in the industrial gas turbine business. One of these challenges was to redesign the turbine with arelatively new engineering team. Opportunities for improvement in design for manufacturability led theproject management to initiate an effort to correct manufacturability problems in large structural castings.The success of this effort led to the project, which serves as the basis for the remainder of the thesis: toimprove the manufacturability of precision cast parts and to develop ways to improve the designorganization's ability to learn from experience in manufacturing.

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SECTION 3: THE BUSINESS CASE FOR IMPROVING FEEDBACK AND ORGANIZATIONALLEARNING

3.1 INTRODUCTION

The aim of this section is to show the value of organizational learning within the firm, particularly the extentto which the design organization learns the expertise to develop more manufacturable products. Building aknowledge base requires the investment of resources, some of which are described in following sections.This section builds a framework for justifying that investment. A sinple model of the learning process isused to illustrate its nature as a dynamic system of elements and to show the importance of all of theseelements of learning from experience.

3.2 A MODEL OF DFM LEARNING

Senge (1994) emphasizes the need for learning organizations to adopt a "systems" perspective. Sengesuggests that many organizations are limited in their ability to learn because they perceive every effect ashaving a single cause and fail to see the effect that businesses, teams, and individuals are parts of largersystems. The process of learning from experience can be thought of as a system of competencies workingtogether iteratively.

Figure 5 illustrates the process by which the design organization learns design for manufacturability fromexperience. For an explanation of casual loop diagrams, see Appendix C. The stock labeled "DFM" is anabstract measure of the design organization's ability to design manufacturable products. The diagram showshow the DFM knowledge is gained from experience. The "Manufacturability" of designs is determined bythe team's "DFM" knowledge and "Knowledge Management Effectiveness", or ability to access and utilize itsknowledge. The "Manufacturability Gap" is the amount by which the design falls short of perfect or "100%Manufacturability." Depending upon the "Quality of Communication with Suppliers", some portion of theinformation needed for improvement is fed back to the design team as "DFM feedback." The "retentionfraction" is a measure of the portion of the feedback that is converted into useful DFM knowledge.

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retention

Retained fractionlearning + Quality

DFM feedback.s.a confmunicatio

DFM nith

DFM Learning suppliersloop

Learning Manufacturabilitrate _y Gap

Manufacturabilit

yZ/+Knowledge

ManagementEffectiveness

I00oManufacturable

Figure 5 A causal loop diagram of the DFM learnming process.

Three aspects of the organization contribute to the effectiveness of the learning process. These are "Qualityof Communication with Suppliers," "Retention Fraction," and "Knowledge Management Effectiveness,"representing the organization's ability to obtain, preserve, and use feedback from manufacturing. Each ofthese capabilities requires an investment of resources. An effective structure must be built and maintainedfor receiving feedback from manufacturing. Systems and people must be dedicated to organizing and storingthis information in an accessible form. The degree to which these systems are utilized determines their valueto the bottom line.

Figure 6 suggests some ways in which learning impacts cost. A product that is more difficult to manufacture(large "Manufacturability Gap") will consume more engineering resources redesigning parts and processes. Itwill cause more scrap and rework in the process of making these improvements and will cause significantdelays in delivery. The penalties for late delivery can be severe. The "Cost per Project" is simply the sum of"engineering cost" "scrap/ rework cost" and "delivery penalties."

Appendix D contains the details and formulation of a more complete form of the same model. Simulationwill show what may already be clear to the reader: the greater the organization's ability to obtain, store anduse feedback from manufacturing, the lower projects will cost. Because of the model's assumptions, "Qualityof Communication with Suppliers," "Retention Fraction," and "Knowledge Management Effectiveness,"each have an equal impact on cost. The model is not suitable to weigh the relative importance of the three,but instead illustrates the fact that all three aspects of the system are critical to effective learning.

It is relatively straightforward to implement a reporting system that requires manufacturers to recordproblems that occur in production. It is equally straightforward to record this information for future use, asis currently done by the NCR database. It is quite another matter to make use of such a database. Theusefulness of a knowledge base depends largely on the way it is organized and recorded. While it is true thatdesigners must be motivated to use past knowledge, motivation is not enough. The knowledge must beaccessible. The recommendations in section 7 contain suggestions for improving the accessibility of DFMknowledge.

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retentionRetained + fractionlearning±

+ Quality ofDFM feedback -- communication

DFM + with suppliersDFM Learning

loop

rate Manufacturabilityrae, .- Gap

Manufacturabili y -

Knowledge 100% DeliveryKnowledge ± + Penalties

ManagementEffectiveness

Scrap/Rework

cost

Cost per Project

Engineerincost

Figure 6 The learning process and associated costs.

3.3 SUMMARY

Products that are difficult to manufacture will cost more. Manufacturability can be improved when thedesign organization learns from experience. The model presented in this section shows that organizationallearning depends on investment in the organizations capability to obtain, record, and use feedback from themanufacturer. The recommendations in section 7 suggest ways to improve these capabilities. The followingsection describes the methods by which the origins of these recommendations were discovered.

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anIUac r e, I %

SECTION 4: ACCOUNT OF THE PROJECT

4.1 INTRODUCTION

As explained in section 1.4, the aim of the project was to develop ways to build a knowledge base ofprinciples and rules for improving the manufacturability of product design. The project plan consisted of datacollection and analysis, leading to a set of recommendations and, to the extent permitted by time,implementation of these recommendations. The following list describes the basic tasks, some of which werecarried out in parallel:

Selection of pilot components

Analyze Nonconformance Reports

Understand and analyze

The design process

Technical requirements of the components

Manufacturing processes

Recommend

Improvements in dealing with suppliers

General design principles

Feedback tools

4.2 NONCONFORMANCE REPORT (NCR) ANALYSIS

The project began with an analysis of the NCRs generated by suppliers in the production of precision castparts. Specifically, two pilot components were chosen for the analysis, the first stage low-pressure turbineblade and vane. The defects raised in the NCRs were collected and analyzed for trends. The quantity ofdefects identified by geometric location was very small, however, and not useful for a statistical analysis of thekind previously performed for large castings. Instead, the defects were categorized by type. Those types thatoccurred more frequently were investigated further as described below.

WHAT NCRS TELL

Except in the cases where the obligation to report nonconformance had been waived, NCRs describe theconditions under which parts were out of tolerance and either accepted, reworked or scrapped. At a macrolevel, this allows one to break down the total amount of scrap and rework by engine, part, process, supplier,or any of a number of other fields.

For example, one problem that was mentioned in a number of NCRs was a lack of material on datumsurfaces, listed as a casting defect. Upon further investigation, it was discovered that the machining supplierwas using, as a slave datum, a surface that was designed to be left as cast. This problem is described in detailin section 5. The NCRs indicated that there was a problem, but it required further investigation to actuallydetermine what the problem was.

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WHAT THEY DONT TELL

A process may run perfectly, without producing nonconforming parts, and still be excessively slow, costly, oraltogether redundant. The NCR will not indicate that a part could be made cheaper or more quickly byanother method without compromising customer requirements. NCRs don't give a great deal of insight intothe root causes of problems. Rather, they indicate places or operations where problems may have occurred.It is then necessary to follow up these indications with further investigation.

The NCR database was difficult to analyze because of inconsistency in use and the limited number of fieldsavailable. The same form is used for any kind of defect found in a part as a result of a manufacturingoperation. It is, therefore, not particularly useful for analyzing the locations of specific types of defects,statistically, nor is it useful for analyzing a large quantity of exceeded tolerance errors. Contrary to thespecification for filling out NCRs, some reports included descriptions of more than one kind of problem perreport. Also, the defect related information and serial number list was often included only in the form of adigitized picture file. It is not possible to search for information in picture files, since the database is onlycapable of searching for alphanumeric text.

The reports actually had many fields for the manufacturer to complete. However, for a defect analysis of anydetail, the most important information was not organized into fields, but was entered as open text. Thismade any kind of statistical analysis of the data (for example tolerance deviations, grouped by feature) a verymanual and time-consuming process. Some recommendations in the following section resulted from thisanalysis. Some deal with the use of the NCR database itself.

4.3 INTERVIEWS WITH DESIGNERS

While analyzing the NCRs, it was possible to interview the engineers who had designed the parts. Theseinterviews gave a great deal of insight into the concurrent engineering process used, what went well, and whatcould have been improved. This insight contributed to the benchmarking analysis and the recommendationsin the following sections. Designers also shed light on the performance issues that drive the technicalrequirements imposed upon the design.

4.4 INTERVIEWS WITH SUPPLIERS

Defects raised in NCRs led to inquiry into their causes by interviewing people at the factories that made theparts. Although some problems that arose in manufacturing could be observed from the NCR record, theseproblems and more all came out in the interviews. Unlike the large-casting project, the manufacturingengineers at the suppliers were already aware of the features that tended to raise NCRs. More importantly,they often knew the root causes and were able to explain the circumstances surrounding them. They werealso able to describe the concurrent engineering process from their perspective, to evaluate it, and to offersuggestions for improvement.

The supplier and designer interviews were the major sources of information used to analyze the most recentiteration of concurrent engineering, and to develop the following recommendations for improving theprocess. These recommendations fell into three categories: the supplier relationship, design formanufacturability (DFM) principles, and tools for developing a knowledge base of DFM principles toimprove future iterations of concurrent engineering.

4.5 SUMMARY

The majority of the project consisted of data collection and investigation into the causes of problems inmanufacturing development of the GT24 and GT26 B version precision cast turbine components. It wasdetermined that the existing system for reporting manufacturing problems was inadequate as a tool fororganizational learning. Defect data was collected and stored, but was not easily accessible for use in avoiding

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the same problems in future design projects. Through interviews with designers and process developmentengineers, new insights were gained as to the origins of manufacturing defects and problems in development.The result of these investigations was a series of recommendations for improving design, which should beincorporated into the organization's knowledge base of design for manufacturability, and ways in which theorganization can improve the feedback it receives and the way it uses this feedback in future designs.

The following recommendations were presented to members of the supply chain management and designorganizations. The recommendations are grouped into three categories, dealing with suppliers, designingparts, and learning from manufacturing experience. The background and significance of eachrecommendation are included for clarity.

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SECTION 5: RECOMMENDATIONS FOR DEALING WITH SUPPLIERS IN DEVELOPMENT

5.1 INTRODUCTION

It was expressed more than once by leaders in the design organization that the issues addressed by thefollowing recommendations should be separate from an analysis of design and the concurrent developmentprocess because they relate to the supply chain. However, each of these recommendations represents animprovement strictly in terms of quality of product development and the building of a manufacturingknowledge base within the design organization. In addition, Fine (1998) suggests that the design of thesupply chain is an integral part of a competitive concurrent engineering effort and is a critical competence tomaintain within the design organization, rather than an issue to be handled by a separate supply chainmanagement group.

5.2 COMMIT TO A CAPABLE SUPPLIER EARLY

In the environment of Concurrent Engineering, it is important to make decisions as early as possible in orderto minimize costly rework. In order to reap the benefits of concurrent development, suppliers must beidentified early so they can guide the design from a manufacturing perspective. Before suppliers will invest inthe development of a new product significantly, they will require some level of assurance that they are not justhelping to develop a product for someone else to produce. This is especially true for operations likemachining, which could be done by any of a large number of suppliers.

Traditionally, contractors were selected by competitive bidding after a design was complete. While this hasthe advantage of minimizing part of the manufacturing cost (process inefficiencies and suppliers' profitmargins), there are already costs designed into the part which even the most efficient manufacturingoperation cannot remove. These built-in costs are the motivation for integrating design and manufacturing.Through cooperative development, designs are more manufacturable and inherently less expensive toproduce.

This does not preclude a second supplier for each part. Sufficient commitment could be made byguaranteeing a minimum percentage of the business to a partnering supplier, subject to minimum qualitystandards. This agreement could be used to form the necessary partner relationship with a supplier todevelop the product concurrently. In fact, it is unwise to depend upon a single source for many reasons. Acompany that does so is exposed to the risk of that supplier's ability to deliver, which could be affected by theactions of a competitor. It is also subject to the supplier's monopoly power, especially if, in cooperativedevelopment, the design is optimized for that supplier at a significant cost advantage over other suppliers.Careful management and engineering judgement must be exercised to avoid this condition.

CHALLENGES

The organization seems to be moving in this direction already. The Engineering organization is naturallywilling to do this, since it benefits them at no obvious cost. There is more likely to be resistance from thesupply chain and logistics organization, which would like to remain flexible to switch suppliers. The middleground must be established in which a primary supplier can be identified for the concurrent development,with some allowance for doing business with a second supplier. The agreement can guarantee, underreasonable circumstances, a certain percentage of the business to the primary supplier.

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5.3 INVOLVE ENTIRE CHAIN IN CONCEPT PHASE

The principle of early supplier involvement applies to not only the casting supplier, but downstream suppliersas well. In this context, the term downstream refers to suppliers of processes that follow casting. All of theseprocesses are upstream relative to AAP.

If the development of upstream processes is carried out without the input of suppliers of downstreamoperations, there is a greater opportunity for inherent costs to subsequent stages to be built into the design ofthe early stages. For example, if only the casting supplier is involved in the casting design, there is noopportunity for machining suppliers to suggest ways in which the casting could be changed to reducemachining cost. The same applies to any downstream supplier. Therefore, it is best to involve the entiresupply chain from the beginning, to save the costs of tooling rework and to minimize the total manufacturingcost of the product.

This is an important part of adding the Supply Chain Design dimension to traditional concurrent engineering(product and process design). Fine (1998, 124) calls this broader view three-dimensional concurrentengineering (3 DCE).

Hookfeature

Figure 7 Vane 1 hook feature

EXAMPLE: VANE 1 HOOK FEATURE

One problem that might have been prevented by the insight of subsequent suppliers was the clearance in thetrailing edge hook feature of Vane 1. There are many dimensions to control in casting a turbine component.Although computer numerically controlled coordinate measuring machines are used for this purpose, themost important dimensions must be emphasized to ensure control. The hook was designed to be cast withclearance for assembly into the stator. The only part of the cast feature that was designed to be machinedwas a pad on the underside of the hook. The geometry of this feature was not constrained by strengthrequirements, but by assembly features. However, the cast surface inside the hook of the actual partsinterfered with mating parts. As a result, an EDM operation was added to remove the excess material andpermit assembly of the Vanes into the stator, adding about CHF 75,000 to the annual cost of machining, inaddition to extra development and production delays. It was noted by the machining supplier that this could

31 -

have been prevented if suppliers of subsequent operations had been involved in the casting development. Itis possible that a team member from assembly would have ensured that the casting supplier control thisdimension in the interest of ensuring the possibility of assembly.

OTHER EXAMPLES

A problem with laser-drilled cooling holes, described in detail in section 5, arose in machining, but was causedby the casting design. The best method for stopping the laser beam is to block it with strips ofpolytetrafluoroethylene (PTFE). The surfaces of many precision cast turbine parts are covered with blind-depth holes for cooling air. Similarly, the need for excess material on surfaces to be used as slave datumfeatures must be included in the casting design, also described later. Another example was the unsuitability ofthe cast surface for brazing, as designed. This led to an additional machining step to erode a surface forbrazing, which, in turn complicated the brazing process by adding a step to remove the recast layer formed byEDM.

CHALLENGES

The engineering organization is starting to adopt this practice as well. New development projects are takingsteps to involve machining, coating, and assembly suppliers in the early stages of development.

5.4 ALIGN INCENTIVES

PAYMENT BASED ON QUALITY

If a supplier gets paid equally, regardless of part quality, there is little incentive to make parts to satisfy thedesign requirements. For example, a part that has only half the intended lifetime is worth much less than apart made to specification. Quite a few parts raised in NCRs were accepted with the restriction that the partsbe marked as having reduced lifetime. However, since suppliers were paid the same for parts with a reducedlifetime, there was less incentive to make the effort to improve the process that delivered poor quality, andlittle reason to recommend design improvements.

Suppliers are often too small to absorb the complete risk of defective parts. However it is only necessary toprovide a sufficient financial incentive to motivate behavior which is compatible with the customer's goals.This suggests an arrangement where minimum quality standards are established consistent with a predictedtarget lifetime. Price penalties should be set for acceptance of parts with defects leading to a reducedpredicted lifetime.

The same must apply for scrap. If the manufacturer cannot bear the full risk of scrapping parts, they must beaccountable for some portion of it. In the ramp-up phase, poor quality in ECM drilling of the trailing edge ofBlade 1 resulted in approximately IF 390,000 in scrap castings. It is likely that the supplier would havebeen inclined to correct the problem earlier if required to pay a portion of the scrap cost.

LIMITED NC ACCEPTANCE PERIOD WITH REGULAR INTERMEDIATE MILESTONES

If nonconforming parts are to be accepted for a limited time during development, that time schedule shouldbe made clear to the suppliers and should include regular events requiring improved quality. Nonconformingparts should never be accepted without clear plans of corrective action and time commitments by theresponsible supplier.

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ESTABLISH A REGULAR DELIVERY SCHEDULE

In order to ensure the timely resolution of quality issues, it is important to require regular deliveries from eachsupplier. This brings manufacturability problems to the surface more frequently, reducing the delay incorrection and the resulting accumulation of bad parts in the system. It also creates the incentive to solvethem either through process changes or through changes in specifications. Every type of part required froma supplier must be delivered to a regular schedule. Otherwise, it is tempting to deliver an excess of parts thatare less costly and to delay the production of more problematic parts. Ultimately, regular delivery of therequired parts is compatible with a lean production system and is in the best interests of both the customerand the supplier.

ENCOURAGE ACCURATE COMMITMENTS

Many of the problems encountered in the development phase result from the fact that suppliers over-commitin capacity planning in order to ensure full utilization. This is analogous to the airline industry's practice ofover-booking flights to ensure full loading of aircraft. This practice continues to satisfy customers if they aresufficiently compensated to wait for a later flight when their original flight is full. However, if there is nopenalty for underestimation of capacity, the supplier's dominant strategy is to over-commit.

In the present situation where AAP's customers defer the risk of late delivery by requiring penalties forlateness, AAP is obligated to accept as many parts as possible. This lowers the incentive for suppliers toimprove quality as mentioned above. It also drives them to maximize production efforts at the expense ofquality improvement. There are several examples of quality problems that took months to resolve becauseAAP was desperate for parts and was forced to accept a lower standard. For instance, many engine sets ofblades were accepted with excessive airflow measurements, although this causes problems later. The partshave to be mixed with lower-flowing parts to avoid excessive losses and efficiency problems.

This could be addressed in more than one way. AAP could purchase capacity, rather than ask forcommitments to produce a certain number of parts. This, however, depends on the supplier to efficientlyutilize the capacity to produce the right parts. Alternatively, the supplier could be required to pay pricepenalties for late deliveries of promised parts. This would force the supplier to reassess risk in light of thecost of over-comnitment.

C-ALLENGES

Alignment of incentives will be more difficult to achieve than the other recommendations in this section sinceit requires careful contract design. This is not helped by the fact that the organization seems to resistsuggestions to change the contracts.

The basic elements of the new contracts should include price penalties for parts accepted with limitedlifetimes or other quality deficiency and for late delivery of promised parts. This cannot be introducedwithout also including a penalty for excessive scrap. If the supplier is not accountable for scrap and only addsa small part of the total value of the part, then he will be inclined to simply write off a part as scrap, ratherthan address quality problems.

5.5 SUMMARY

After discussions with suppliers and designers about the causes of problems discovered in the NCR analysis,it was determined that there are a number of opportunities to improve the DFM learning process by changingthe way the company deals with its suppliers. To fully realize the value of this partnership, all the suppliersthat will be performing operations on a part should be involved from the beginning in the design of that part.

33 -

In addition to the obvious commercial implications, accurate and timely delivery of parts is also essential togetting effective manufacturing feedback and to building a knowledge base of DFM principles. The nextsection describes some of the principles that can be learned from this project.

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SECTION 6: RECOMMENDATIONS FOR DESIGNING PARTS

6.1 INTRODUCTION

After an analysis of the version B design, the following suggestions were made to improve future designs.These suggestions represent the type of knowledge that must be available to all designers of suchcomponents. Each recommendation is the result of an investigation to some problem that causednonconformance or delays in product delivery, both of which result in unnecessary cost to the company.

MINIMIZE SENSITIVITY OF KEY CHARACTERISTICS TO PROCESS VARIATION

Every manufacturing process results in some part-to-part variation. This variation can affect how nearly apart meets the requirements of the customer. With any design, there are measurable characteristics of afinished part that are critical to satisfying a customer need. However, the relationship between variations inthe manufacturing process and variations in these characteristics is defined by the design. Thornton (1999)defines key characteristics (KCs) as

... the pmro&t, sub-assenbly, part, and pwxess featus that siiflcanty inpa thefinal cost, perform x,or safety ofa pdw dxn the KG zwyflrn naninaL Special conbvn shoLd be applied to those KG zbemthe cost ofzriaton justifies the cost ofcntmmL

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Cost ofCOperationT

Engine Time BeforeEfficiency Reconditioning/

Replacement

Cooling SurfaceAir Used Temperature

Cross-SectionalArea of TrailingEdge Holes

Core

Shape

CorePosition

CustomerRequirement

Product KCs

Subsystem KCs

Part KCs

Process KCs

Figure 8 Key Characteristicfloudozenfor Vane 1 airflow example.

A good example is the airflow of a cooled vane with holes cast in the trailing edge, which is critical to theefficiency of the engine and the lifetime of the vane and downstream turbine stages. Figure 8 shows aportion of the KC flowdown for this part. The airflow is largely defined by the geometry of the coolingpassages, which are produced by the core. At the trailing edge, where cooling air exits these passages, thecross-section of the core determines the size of the holes. The core position tends to vary from one part tothe next. If the edges of the core are not parallel, the cross-section at the trailing edge will vary with coreposition. Therefore, the relationship between core position and exit hole size is determined by the anglebetween the core edges, a design parameter. Figure 9 shows a cutaway view of the cored exit holes of a typicalvane. The edges of one hole are extended to show that they are not parallel. In this case, since making theedges parallel has no negative effect, it makes sense to do so.

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Exit HoleHeight

Nonparalleedges

External View Core Position 1 Core Position 2

Figure 9 Effect of core shift on size of trailing edge cooling air exit holes.

The problem of the sensitivity of key characteristics to manufacturing variation is analogous to the impact ofproduct failure on customer requirements, such as safety or cost. Therefore a systematic approach toevaluating the sensitivity of a design to manufacturing variation would resemble a Failure Modes and EffectsAnalysis (FMEA), a common design tool (http://www.fmeca.com/Default.htm). The modes of variation areanalogous to modes of failure. The manufacturing process can be systematically analyzed for variation modesthat are significant and difficult to control. For each of these modes, the design can be analyzed for the effectof each variation mode on important top-level performance characteristics. Decisions can then be made tominimize this impact.

Thornton (1999) proposes a model for quantifying the effectiveness of monitoring a particular KC. Thiseffectiveness is analogous to the Risk Priority Number in FMEA. Since it is often economically infeasible tomonitor every tolerance, this model allows the designer to prioritize tolerances and to select those that arecost-effective to monitor.

CHALLENGES

The difficulty of evaluating the sensitivity of a design to manufacturing variation depends greatly on the levelof detail and complexity of the model used. Figure 10 illustrates, for three solution types, the relationshipbetween the complexity of the analysis (the number of variables considered) and the cost of evaluating thesensitivity of the design to variations in manufacturing. As complexity increases, there is a point where eachmethod becomes prohibitively expensive. Basic intuition can be applied quickly to simple problems involvingonly a few varying parameters and quality characteristics. However, this problem quickly becomes dauntingas the numbers of varying parameters and quality characteristics are increased. Mnemonic lists help structurethe analysis and indicate which parameters are important, so the sensitivity can be evaluated systematically.But this method, too, becomes infeasible when the problem becomes very complex. This argues for the useof mathematical models that can be analyzed by computer when the complexity is large.

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Models

nemonic listsrtuition

0 1

Complexity of problem(number of variables)

Figure 10 Cost of solution curs for thr basic types of sensitivity analysis

However, if the project is constrained such that the basic initial cost of modeling is too high, steps must betaken to simplify the problem so that one of the other two methods can be used. For example, a fewvariation parameters and quality characteristics that are known to be problematic can be collected into listsand analyzed manually at a lower cost. This may not anticipate all the problems, but may maximize thechance of catching them given the time constraint.

There are many business analogies to this situation. In business strategy, the analysis of industries could easilybe monstrously complex. Mnemonic lists are used to help a strategists systematically consider the importantfactors in any industry (e.g. Porter's 5 forces, Oster 1998, 31), without overlooking an obvious player. Thesame is true in marketing. The "4 Ps and 3 Cs" mnemonic helps one address all the important issues ofsuccessfully marketing a product or service.

Similarly, there is an initial investment (hence, the higher base cost) in developing such a list from experience.However, once the list is established, it can be used to avoid overlooking important opportunities forvariation in quality characteristics due to manufacturing. Using the database tools described below (e.g. anIntranet) this list can be maintained and updated with time and experience.

As previously mentioned, the model proposed by Thornton attempts to prioritize tolerances by theeffectiveness of monitoring them, thereby reducing the complexity of the monitoring task. If there issufficient time to use it, this model represents a more mathematically systematic approach to simplifying theproblem.

6.2 MAKE COOLING CHANNELS ACCESSIBLE

One example of considering the needs of subsequent operations in the design and development of earlierprocesses is the accessibility of the cooling channels. Figure 11 shows a simplified blade with cored coolingchannels. The cooling holes must be drilled from the outside into the channel, but must not continue onthrough the blade. In the figure, the laser would be drilling more or less into the page to form the coolingholes shown in the external view. Note from the cutaway view that these holes must not continue throughthe rest of the part. When drilling cooling holes with a laser, it is necessary to stop the beam from striking theback wall. This can be done with wax, but is more reliably done with strips of PTFE (Teflon). However, theuse of PTFE strips requires easy access to the channel into which the holes are to be drilled.

Serpentine cooling channels, similar to those shown in the cutaway view of Figure 11, achieve more effectivecooling than simple, straight channels. These cooling channel shapes are often used to cool parts that are

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exposed to very high temperatures. However, these shapes can make insertion of PTFE strips difficult or

impossible.

If prior operations leave no direct opening into the right portion of the channel, wax must be used instead.

Unfortunately wax is not as reliable, since it tends to melt during the laser drilling operation. This is the typeof problem that would be identified early if the supplier of the laser drilling operation were involved in the

design of prior operations. Although this problem is well known to designers, a laser-drilling expert would beable to provide intuition on the additional cost of drilling into blind channels.

One option might be to leave one end of the blade open until after the laser drilling operation. In any case,there are usually small holes in the end of the blade left by pieces of the core used for support during casting.These small holes must be plugged or covered at some stage. If these holes could be left large enough for

PTFE strips, the remaining problem would be to find a way to block them afterwards. The cost of the

additional hole closing operations would have to be weighed against the cost of drilling into blind channelswithout PTFE.

Ina

CoolingHoles

External view

ccessaPori

CCoo

Chan

ble~ion,

21

n(

)redlinnels

Cutaway View

Figure 11 Simplified blade showing cooling air passages and exit holes

CHALLENGES

The need for protecting internal walls from penetration when drilling laser holes has been well known for

some time (Corfe 37). Quality data from the laser drilling blades with inaccessible channels can be used to

estimate the cost, in additional scrap, of eliminating the possibility of protecting a surface with PTFE. This

- 39 -

cost can then be weighed against the potential benefit of blind channel designs in the future. The challengehere is to estimate this cost and to incorporate it into the decision-making processes of designers.

6.3 PROVIDE FOR SLAVE DATUM FEATURES

Another example of considering machining needs in the casting design is the need to fixture parts offsecondary or slave datum features. All dimensions on a cast blade are referenced to six points on the castsurface of the airfoil. However, it is not possible bear the loads of machining operations such as grinding onthese six points. Therefore, datum surfaces must be machined by fixturing the parts on the six locatingpoints. Then these new surfaces can be used to fixture the part for subsequent machining operations.

ME-

Surfaces usedas slave datumfeatures

Figure 12 Slave datumfeature

In the case of the first low-pressure turbine stage vane, the machining supplier used surfaces with excessmaterial for machining these slave datum features. However, the casting was not designed to always haveexcess material on these surfaces, since the parts could have insufficient material for machining these featuresand still remain within the drawing tolerance.

Although the situation was corrected by altering the wax die, many parts were scrapped in the interim andwritten off as casting defects. This could have been prevented if the machining supplier had specified theneed for material in these areas during the casting design. It is likely that this request would have been madeif the machining supplier had been more directly involved during the casting design.

6.4 PROJECT PLANNING INTEGRATION

To prevent costly delays, design information must be delivered and used according to schedule. Delays alongany point in the critical path lead to delays in finished product delivery. Suppliers expressed concern that theyhad not received certain pieces of information early enough. For example, a machining supplier suggestedthat it had received the details of airflow testing late. This resulted in late delivery of the first sets of parts tobe tested.

- 40 -

The fact that suppliers recognize this as a problem emphasizes the need for integrating the project

management of the suppliers' process development with that of the overall product development (Fine 1998,186). This would allow designers to estimate the impact of a design change on tooling cost and delay of

project completion.

CHALLENGES

The challenge in managing the project in the larger sense is to collect all the relevant activities and their

associated costs, estimated durations, and dependencies from the suppliers. At the present, the supply chain

organization has difficulty determining even the current state of work in progress. Suppliers must be

convinced of the need for increased information sharing to permit project planning to be integrated.

6.5 UNDERSTAND IMPACT OF DECISIONS AND CHANGES ON THROUGHPUT TIME, COST AND

QUALITY

In order to maximize the present value of future earnings, the impact of design decisions on throughput time,development time, manufacturing cost, and product quality must be understood. This suggests that a

heuristic cost model of the development process is required. Although the effectiveness of such a model

would increase with its accuracy and precision, there are practical limits to its complexity. Design-related

factors that affect the cost of producing engines include the elements of Table 1.

Table 1 Elements of a cost model

Manufacturing Cost

Work-in-process, a function of throughput time

Tooling and machinery cost

Material cost

Scrap rate

Labor, rework

Other Costs

Late Penalty, a function of total throughput time for early sets

Performance penalty, a function of efficiency and power output

Replacement cost, a function of predicted lifetime

Overhead, including design

The basic formula for NPV is the discounted revenue stream minus the discounted cost stream, including the

initial one-time investments (engineering time, tooling, and other development costs). Figure 13 shows the

significance of several cost, revenue and timing components. The model assumes an initial development cost

and costs associated with the production of each unit sold. Penalties and scrap costs are reduced with time

and learning. The throughput time is defined as the time between the initial input of raw materials and the

delivery of the product. Revenue from the sale is assumed to coincide with delivery.

- 41 -

Throughput Time - <Revenue from sales

Penalties A k

2o T

Time to Market

U -ime

Design Aoin

ScrapAllowance anufacturing

aterial costcost

Figure 13 A simplifiefmncial mldel of the custs and rwues ofa single ngineprct

Engineers must balance performance and manufacturing cost. Since the design fixes these costs, it makes

sense to have the necessary information available to help them make informed design decisions. Examples of

manufacturing cost estimations relating the physical properties of the product to process costs are included in

Appendix E.

CHALLENGES

Though it seems simple, finding the relevant cost of a component can be difficult. The relevant cost dependslargely upon which decision is being made (Fine 1998, 237). Designers have developed the tools to determinethe effect of a design decision on performance and lifetime. The effects of the same decision on throughput

time and the manufacturing costs of Table 1 are more elusive. Designers require information about the

supplier's processes, something suppliers often see as proprietary. Again, suppliers must be assured a mutual

benefit from the partnership in order to become more involved in the design process.

Appendix E shows how the relative cost of drilling holes by laser and EDM can be estimated. If these cost

functions are included in the design review software, it seems more likely that they will be used, since such

calculations take significant time to formulate and the underlying costs take time to gather. If many of these

cost calculations were standardized and automated, designers should be more inclined to use them as decision

support tools.

6.6 KEEP MANUFACTURER INFORMED EARLY ABOUT POSSIBLE CHANGES

Concurrent engineering inevitably requires design iterations and changes to the design during manufacturing

development. The challenge is to minimize the negative impact of these changes on manufacturing cost,

quality and time-to-market. Ideally, the manufacturer would like to have a subset of the total design that can

be considered fixed, in order to begin development and tooling while the rest of the design is finished.

Alastair Clark, an AAP engineer, suggested a means of communicating the certainty of permanence of designfeatures. In addition to nominal geometry and tolerance information, the design documentation could also

include an estimate of the likelihood that each dimension will change. This need not be a precise probability,but a categorical estimate of which features are essentially fixed and which are likely to undergo further

- 42 -

iteration. Such information could be communicated through color-coded features, indicating how certain thedesigner is that the feature will remain the same in the final design.

Krishnan (1993) develops a model for minimizing the total duration of overlapping (concurrent) activities inthe face of uncertainty in the value of evolving (unfinished) design parameters and "sensitive" processdevelopment activities, the cost of which increases with changes in these parameters (e.g. costs incurred bychanges in dimensions after tooling has begun). Krishnan (1992) also recommends ways to improve thetransfer of information from design to process development through timing, content, and preliminaryinformation.

The formulation of Krishnan's model is listed in Appendix F. Design evolution is a measure of certainty ofthe value of a particular dimension. Assuming that, at any given point during the design phase, a maximumand minimum value of the dimension can be specified. The evolution is defined as the fraction of theoriginal gap between minimum and maximum values, which has been eliminated by raising the minimumand/or lowering the maximum. Therefore, evolution is 0 at the start of design and 1 at the end. Sensitivity isthe degree to which the duration of the downstream activity is lengthened by a change in the design variable.

Since some of the parameters may be difficult to obtain quantitatively, Krishnan suggests a qualitative methodfor making overlapping decisions. If evolution and sensitivity can each be classified as high or low, the chartin Figure 14 can be used to decide what kind of overlapping strategy should be used.

Degree of upstreamevolution

SlowEvolutionCase

Degree of upstreamevolution

ast

Process Evolution ProcessTime Case Time

Increase inDownstreamDuration

LowSensitivityCase Design

Change

Increase inDownstreamDuration

HighSensitivity DesignCase Change

Figure 14 Recamnmd otwrlap strategy grvm estimates ofezalution and sensitivity

As with most engineering and management decisions, the effects must be weighed and balanced. Figure 15compares the effects of each overlapping strategy on quality, effort, and lead time.

- 43 -

Iterative DistributiveOverlapping Overlapping

LL A2 Ap

Divisive Overlapping Precipitativeor No Overlapping Overlapping

Degree of upstreamevolution

SlowEvolutionCase

Degree of upstreamevolution

ast

Process EvolutionTime Case

L - No

Increase inDownstreamDuration

LowSensitivityCase Design

Change

Increase inDownstreamDuration

HighSensitivity DesignCase Change

Figure 15 Types of owrlapping and the resultmg perfomanxe tradeoffs

CHALLENGES

Preliminary information release seems more difficult to implement since it represents additional effort on thepart of the designers. In the immediate time horizon, simple certainty information can be communicateddirectly. For example, if the airfoil shape is considered fixed, the designer can simply say so and allow thedevelopers of the drilling processes to begin programming and fixture designing based on the airfoilgeometry.

In the future, this would be a prime candidate for incorporation into the CAD software. The challenge atthat point would be getting the designers and manufacturing engineers to use it. This seems to be a matter ofillustrating its value with one of many examples of cost and delay resulting from poor communication whichwould be corrected by the use of such tools.

6.7 ACTIVELY INCORPORATE MANUFACTURING FEEDBACK

The feedback of manufacturing experience into design requires that the documentation of lessons learned bemade available in a convenient format for reference. It also requires that designers actively seek thisknowledge in the development of new designs. The most useful guidelines are worthless unless followed.

6.8 SUMMARY

Many of these principles of design for manufacturability are well known, not only by the general engineeringcommunity, but by many engineers at AAP as well. The fact that some of these problems arose suggests theneed for increasing the degree to which such knowledge is distributed among and available to all members of

44 -

ProcessTime

Iterative Overlapping Distributive OverlappingNo quality loss Some quality lossIncrease in Effort Increase in effortSmaller lead time Much smaller lead time

Divisive Overlapping or No Precipitative OverlappingOverlapping Some quality lossNo tradeoff or one of the No increase in effortother three types Smaller lead time

the design team. The company is improving the manufacturing knowledge of the engineering group. This

must continue in order for the company to remain competitive. The next section describes ways the

company can go about improving the distribution and accessibility of knowledge.

- 45 -

SECTION 7: RECOMMENDATIONS FOR LEARNING FROM EXPERIENCE (FEEDBACK TODESIGN)

7.1 INTRODUCTION

The previous section described important principles to be included in a knowledge base of design formanufacturability. This section suggests ways the company can build this knowledge base and make itaccessible to the designers. Particular emphasis is given to the knowledge gained from experience in productdevelopment. This is how individuals learn best, by experience. It is important, however, that theorganization as a whole learn from the experience of individuals. As illustrated by the lessons learned fromthe B version design in the previous section, it is not enough for a few individuals to learn from experience.There is a great deal of savings to be gained if this experience is available to all designers. This reduces thenumber of times the same lesson must be learned through trial and error.

The following suggestions include methods of building the knowledge of individuals, as well as codifying andorganizing knowledge for the entire group. To help build the intuition and expertise of the individualdesigners, it is suggested that they visit the suppliers and share experiences with one another. New lessonscan be learned through analysis of quality data collected by the manufacturers. Databases of experience canbe built for access through the internal computer network Some suggestions for building and arrangingthese databases are given as well.

7.2 SUPPLIER VISITS

It is important for designers to actually have some experience in each of the manufacturing processes used tomake their parts. It makes sense to send the designers to the factories where the parts are made before theystart designing, as well as during development. This allows them to gain intuition in designing formanufacturability and creates the opportunity for them to identify operations that are unnecessary or overlycomplex and expensive for the design intent. It also requires that suppliers be chosen early as partners indevelopment and that they be willing to have such visitors.

For example, Alex Beeck, an AAP component owner, observed that a deburring operation at AETC BMF, amachining supplier, involved extreme care due to a misinterpretation of the specification, which required themanufacturer just to break the edge. This was intended to make the operation easier since the quality of theedge was not very critical. However, it was interpreted to mean that the operator must just break the edge,but avoid cutting any deeper into the part. The operation required careful attention and consumed muchmore time than necessary. When Alex, a designer with a thorough understanding of the design requirements,walked through the operation from start to finish, he was able to observe the error in communication andmake a correction. In the future, this could be avoided by specifying a tolerance on the edge radius.

In visiting suppliers, designers should not neglect assembly. There is a common perception thatmanufacturing ends before assembly begins. However, many manufacturing problems become immediatelyapparent at assembly. Geometrical problems show up when parts don't fit. Assembly is starved when partsare late. Unlike the aircraft engines industry, there is little opportunity to test land-based gas turbines prior toservice because of their size and cost. This makes assembly even more important since it is an opportunity toobserve some of the problems of the design before the engine is turned over to the customer.

CHALLENGES

This is done to some extent already, but should include the entire chain, not just the casting. It is tempting toconcentrate on casting and leave out machining and coating because of the relative cost of casting due to

- 46 -

material cost. However, mistakes that scrap castings in machining cost as much or more than mistakes that

occur in casting. This focus on material cost at casting also neglects to take into account the relative

throughput times of casting, machining and coating. As noted earlier, delays in power plant delivery incur

expensive penalties. A delay in machining or coating represents a delay in final delivery of the part and of the

entire project if the part is on the critical path.

7.3 ANALYSIS OF QUALITY DATA

There is an opportunity to learn from manufacturing experience by analyzing quality data collected over many

parts. Patterns can be found that indicate potential problems. In some cases this suggests a change in the

manufacturing process. Alternatively, it may make sense to change the design specification to make the part

more manufacturable.

NCR

The NCRs of two components were analyzed for patterns in defects. For each component, the defects were

classified by the operation in which they occurred. For Vane 1, some of these defects could be eliminated by

eliminating the operation that produced them. After an investigation of causes of the defects, it was revealed

that the operations were, in fact, not necessary. Some were operations added to correct casting defects.

When the casting defects were corrected, the machining operations were redundant. This was the case for

the hook relief and the brazing surfaces on the platforms.

NCR SERIAL NUMBER TRACEABILITY

In order to apply a similar analysis to the NCRs, one must be able to search NCRs by serial number to find

correlation between different types of nonconformance that occurred on the same part. At the start of the

project, it was not possible to search for every NCR raised by a particular serial number. NCRs generally,though not always, had the correct serial numbers listed with their associated defects. However, these serial

numbers were often included in a form that was readable, but not searchable. For example, many serial

number lists were included as an attached picture or spreadsheet file. The NCR database did not have the

capability to search for numbers in such attachments.

A method of indexing the NCR records by serial number was developed and recommended for all

subsequent NCRs. The method was adopted and is in the process of being implemented. This capability has

the added benefit of permitting a search for all NCRs related to each of the parts in an engine, which may

become necessary in the case of an engine failure and resulting liability investigation. As the number of

NCRs raised using the new method grows, and as old NCRs are converted to the new format, this type of

analysis will be possible, revealing interactions between different kinds of defects.

NCRFAPS, KNOWLEDGE-BASED SYSTEM

The Non Conformance Report Fast Answering Process Software, being developed by Bernard Robic, an

AAP engineer, presents a significantly improved platform for analyzing quality data. Currently applied to the

answering of cooling airflow NCRs, the software accepts data measured by suppliers and generates a

disposition for each affected part. Error proofing is performed at several levels to ensure that the

information is correct before it is accepted. The information for each part is then stored in a database in an

easily searchable form. This allows each manufacturer's airflow quality to be analyzed for process stability,currently a manually intensive process, prone to error.

- 47 -

CHALLENGES

This should be easier since the implementation of serial number traceability in the NCR database. As theNCRFAPS system is used, process control data will be much easier to access and analyze. The measurementswill be stored in a more structured way. Error checking will ensure cleaner data. Once NCRFAPS isdemonstrated in airflow, it should be easier to implement in other areas of quality control. This will nothappen by itself, though. A champion must fight the natural tendency to use a different tool in everydepartment by promoting the value of NCRFAPS to other areas of the design department.

7.4 PRODUCT SUPPORT TOOLS

The Product Support group has defined a process for incorporating field experience into design. Thisconsists of several tools: Experience Response System (ERS), Read-only project status and operating data,Problem History Files (PHF), Design Office, and case studies. This structure would be well suited formanufacturing feedback as well. To avoid the proliferation of information tools, it seems best to try to useexisting structures to build the manufacturing knowledge base. When a new kind of tool is required formanufacturing, it makes sense to integrate it with product support in order to maintain uniformity andcompatibility.

EXPERIENCE RESPONSE SYSTEM

The Experience Response system is a database of documentation of field failures. It contains documents ofvarious forms (including faxes, memos, e-mail messages, and NCRs) that describe the problems and thesubsequent actions and contain links to more detailed reports. These documents can be sorted bycomponent, project, system and other fields and are.indexed for full-text searchability.

PROBLEM HISTORY FILES

Similar to the ERS, Problem History Files contain a description of a problem in the field and the action takento solve it. The PHF form provides a structured approval path for each problem. The records can be sortedby owner, GT type, approver, and status and are indexed for full-text searchability.

PROJECT STATUS AND COMMUNICATION FILES

Project information and the status of problems currently being solved are stored on network servers to whichmost users have read-only access. The Design Office database contains documentation of the proposal andapproval of official design changes resulting from field failures.

The ERS, PHF, and Design Office databases allow easy storage of information describing field experience.However, designers suggested that relevant information is still difficult to access. This system seemsappropriate for the documentation of manufacturing problems and solutions, but can only be effective if theprocess of storing and retrieving the information is made smoother.

CASE STUDIES

The Product Support Team conducts case studies with large groups as learning exercises. Field failures arepresented to the participants, who suggest solutions. These suggestions are compared with the actualimplemented solutions and discussed. For those who participate in these case study workshops, they seem tobe relatively effective. The participants, including design engineers, get a good understanding of the problem

48 -

of interest. When a large number of people are thinking about the same problem, they generate solutions and

ideas that had not occurred to the few who dealt with the original problem. These also serve as an exercisefor introducing new employees to the kinds of problems faced in design. While case studies cannot be relied

upon to communicate every type of lesson learned from experience, they are good for making people awareof major problems that occurred in the field and how these problems were solved. They seem, therefore,appropriate for communicating and studying problems faced in manufacturing and development as well.

CHALLENGES

These tools were recommended because they are already used for field feedback and should, therefore, berelatively easy to implement in manufacturing feedback. The main challenge is to see whether or not theinformation is used. This will depend a great deal on how easily relevant information can be accessed fromthe database. There is great potential to make both the manufacturing feedback and the field feedback morepowerful tools by improving the user interface. This would require a commitment of resources frommanagement to organize the experience data and configure the search tools in a way that maximizes theusefulness to designers. This includes the time of a designer that uses or could use the tools and the time of aprogrammer.

7.5 INTRANET

Within the company's intranet, a structure is being developed for publishing turbine design informationinternally. The structure contains both public and private sections. It allows the user to find test data, lessonslearned, design standards, and other relevant design information through a hierarchical taxonomy. Thisfacilitates knowledge transfer from the receiving end, allowing the user to quickly find and "pull" relevantinformation, rather than wading through volumes of documents or waiting for the relevant memo to becirculated. This intranet structure would be an ideal interface for integrating the Product Support tools andanalogous manufacturing feedback tools.

CHALLENGES

Similarly, this tool will simply require the investment of a designer's time and a programmer's time to developa user-friendly system to allow designers to pull a wide range of relevant information about the project, designstandards, field and manufacturing experience, etc. It only makes sense to incorporate search capability of theproduct support database into this intranet portal interface.

7.6 STONER ULE®

AAP is currently working with a consulting firm, CADFEM, to develop tools to build knowledge into the

design software (CATIA) with a package called STONEruLe@. An object-oriented programming language,STONEie@ provides an interface between the user and CATIA, applying design rules to the user input to

automate some design tasks. The STONErue@ package was already used successfully to automate much ofthe design of vane carriers. It is doubtful that much of blading design could be reduced to rules forautomation. However, there is a great opportunity to use the tool to incorporate rules learned from field andmanufacturing experience into the CAD system to alert the designer of potential problems.

AUTOMATE 2D DRAWING GENERATION

The STONEne@ package is currently being programmed to automatically generate 2D drawings based on3D models of precision cast parts.

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INCORPORATE FEEDBACK INTO MEG

In its "design review" mode, the STONEnie@ software can give the user advice on design features based onpre-programmed rules. When a new rule is learned from manufacturing, it can be programmed into thesoftware for use by all designers. Although the name "stone rules" implies permanence, it is the possibility ofadding to or changing the rules over time that makes the software a powerful tool for knowledge transfer.

CHALLENGES

Again, this will require the time of a programmer and part of the time of one or more design engineers.

7.7 SUMMARY

In order to improve DFM learning, these recommendations for building the design organization'smanufacturing knowledge base were presented to the company. For ease of implementation, acceptance, andmaintainability, many of these are simply modifications of existing tools used by the design team. Thedevelopment of these tools will still require the investment of resources. It may be difficult to quantifiablyjustify this investment, since one cannot predict what problems will be avoided in the future. However, ifthese tools can prevent some of the major problems experienced in the past from recurrmng, the investmentwill be quickly recovered. The following section summarizes the lessons learned and concludes the thesis.

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SECTION 8: CONCLUSIONS

8.1 INTRODUCTION

The project's recommendations achieve both aims of the thesis: to illustrate the importance of knowledge

management in concurrent engineering and to recommend ways to improve it. The recommendations for

dealing with suppliers illustrate the importance of knowledge management and hint at the consequences of

failing to do it well. The mere existence of issues like those that brought up the recommendations for design

calls for improvements in knowledge management. These issues are common to many manufacturing

companies, not just the sponsoring organization. Finally, the suggestions for improving the feedback from

manufacturing offer ways to improve the management of knowledge within the design organization as well as

with manufacturers.

8.2 DEALING WITH SUPPLIERS

In committing to suppliers early, the company reaps the value of incorporating the manufacturers'knowledge

into the design (alternatively, avoiding the cost fixed in the design by excluding this input). At the same time,

careful management is required to avoid becoming dependent upon a single source. Involving the whole

chain means taking advantage of the knowledge of ewry supplier. The value of this is illustrated by several

examples given: the hook feature of Vane 1, blocking the laser, and EDM of the brazing surface. Aligning

incentives shows the synergy of enforcing quality standards, project management, inventory management, and

improving manufacturing feedback.

8.3 DESIGNING PARTS

Minimizing sensitivity to variation requires the engineering organization to have knowledge of the

manufacturer's process variables. Providing for slave datum features requires knowledge of the features to be

used, or at least the issues that drive the choices of these surfaces. Timely information delivery and informing

the manufacturer early both require knowledge of the manufacturer's timeline, cost information, and

sensitivity to changes and integration of the project management of the manufacturing process development

with that of the product design.

Supporting design decisions with cost models requires bringing together cost information from many sources

to the engineering organization. Data from one product introduction must be analyzed to predict the

dynamics of subsequent development efforts. Cost and process information must also be collected from

manufacturers. This requires transferring knowledge from sources that traditionally have had complete and

careful control of it. The political barriers to obtaining such information must not be overlooked as this will

likely be perceived as a threat to the former knowledge brokers' power.

8.4 LEARNING FROM EXPERIENCE

When designers visit suppliers and before, during, and after the design project, they have the opportunity to

gain valuable, relevant knowledge first-hand. Analyzing quality data allows the organization to transform

volumes of numbers into valuable lessons. The product support tools and the intranet help the whole

organization to learn from its individual members. CAD software automates the process of pulling relevant

knowledge into the design process and maps it to appropriate geometric features.

8.5 OPPORTUNITIES FOR FUTURE WORK

There are a number of potential projects for future interns resulting from the recommendations of this

project. There are still problems to be solved in implementing these suggestions. There are opportunities for

future interns to:

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* Facilitate the building of a set of rules for manufacturing that can be programmed into the STONEruk-@software and used in the design review mode to flag potential manufacturing problems. This wouldrequire working with suppliers and designers to collect a set of rules and working with a consultant toprogram them into the software.

* Support the development of the Intranet design manual by working with designers to develop the mostvaluable structure and content and by designing the process by which it can be maintained. This mayinclude incorporating the existing Product Support tools and modifying them to include manufacturingfeedback.

* Develop a cost model of individual manufacturing operations to help the turbine design departmentunderstand the impact of design decisions on TPT, Cost, and Quality. This model could also beincorporated into the design review mode of the STONEruLe® software.

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REFERENCES

ASM Handbook. (1988) Materials Park, Ohio: ASM International.

Boothroyd, G. and P. Dewhurst (1983). Design for Assembly: ADesigner's Handbook. Department of Mechanical Engineering, Universityof Massachusetts at Amherst.

Bralla, J. G. (Ed.) (1998). Design for Manufacturability Handbook, 2nd Ed.New York: McGraw Hill.

Corfe, A. G. (1983) "Laser drilling of aero- engine components."Proceedings of the 1s International Conference on Lasers inManufacturing. 31-40.

Fine, CH. (1998). Clockspeed: Winning Industry Control in the Age ofTemporary Advantage. Reading, Massachusetts: Perseus Books.

Kalpakjian, S. (1995). Manufacturing Engineering and Technology, 3rd Ed.New York: Addison-Wesley Publishing Co.

Krishnan V. (1992). "Overlapping product development activities byanalysis of information transfer practice." Working paper # 3478-92 MS.MIT Sloan School of Management.

Krishnan V. (1993). "A model-based framework to overlap productdevelopment activities." Working paper # 3635-93 MSA. MIT SloanSchool of Management.

Oster, S. M. (1994). Modern Competitive Analysis. Oxford UniversityPress, New York

Powell, J. (1989). "The influence of material thickness on the efficiency oflaser cutting and welding." Proceedings of the 6t International Conferenceon Lasers in Manufacturing. 215-221.

Schimmoller, B. K. (1999). "Balancing compliance with competition."Power Engineering. 103(10): 22-28.

Senge, Peter M. (1994). The Fifth Discipline: the Art and Practice of theLearning Organization. Currency Doubleday, New York.

Springborn, R. K. (Ed.) (1967). Non-traditional Machining Processes.Dearborn, Michigan: American Society of Tool and ManufacturingEngineers.

Thornton, A. C. (1999). "A Mathematical Framework for the KeyCharacteristic Process." Research in Engineering Design. 11:145-157.

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APPENDIX A: CONCURRENT ENGINEERING PROCESS

Figure 16 shows the sequence of events in the product development process. Note that many design andprocess development activities occur concurrently in order to minimize time to market. The following tablebriefly describes each of the tasks listed in Figure 16. See the figure for the sequence of events. Note that thetimeline is not to scale.

Task Description

Component Specifications Project managers create the project plan, including performance and costand Targets targets.

Preliminary Design Project managers, and design team leaders, conduct a feasibility study, andassess potential problems, suppliers and delivery schedule.

Review Preliminary Design The project targets are reviewed and converted into boundary conditions andtargets for the conceptual design.

Conceptual Design, The design team leaders work with the proposed suppliers to estimateManufacturing feasibility, cost, and delivery schedule.Documentation

Concept Design Review Project managers approve the design plan, including boundary conditions.

Concurrent Design Phase A The design team works with suppliers to develop the component designspecifications.

Concurrent Design Phase B A continuation of Phase A with input from Concurrent Manufacturing PhaseAl.

Design Review The project managers review and release the technical drawings and castingand core dies.

Production Documents, The design team works with suppliers to develop production specificationsPhase A and test procedures for each phase of manufacturing (casting, coating,

machining, and assembly).

Production Document Project managers review the result of production process development andReview release pre-serial production.

Component / Design Production parts are tested for conformance to the design intent.Validation

Production Documents, Production documentation is finalized.Phase B

Product Review The results of product development are evaluated and the design is frozen.

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- 55 -

Manufacturing Preparation The supply chain management team coordinates the plan for routing partsthrough the supply chain. Suppliers provide cost and schedule estimates and

expertise to support the manufacturability of the design.

Supplier Selection Orders are placed with suppliers. A delivery schedule is established.

Concurrent Manufacturing, Suppliers provide input to the design team and a draft of production routing.

Phase Al

Concurrent Manufacturing, Suppliers continue to support design and update routing and schedule.

Phase A2

Concurrent Manufacturing, Tools are designed and manufactured. The manufacturing and testing

Phase A3 processes are documented.

Preseries Production Production documentation is reviewed and preserial production is approved.

Release

Concurrent Manufacturing, The supplier provides preserial sets and updates to production

Phase B 1 documentation as yields improve.

Concurrent Manufacturing, The production process is stabilized and documentation is finalized.

Phase B2

Initial Sample Inspection Quality managers approve production processes. Tolerances are fixed.

Transfer Serial Order The result of the development process is documented.

Execution

Transfer Document The design department relinquishes responsibility for production.

Task

Component Spec and Targets

Preliminary Design

Review Preliminary Design

Conceptual Design, Mfg. Doc.

Concept Design Review

Concurrent Design Phase A

Concurrent Design Phase B

Design Review

Production Doc. Phase A

Production Doc. Review

Component Design Validation

Production Doc. Phase B

Product Review

Manufacturing Preparation

Supplier Selection

Concurrent Mfg. Phase Al

Concurrent Mfg. Phase A2

Concurrent Mfg. Phase A3

Preseries Production Release

Concurrent Mfg. Phase B1

Concurrent Mfg. Phase B2

Initial Sample Inspection

Transfer to Serial Order Execution

Transfer Document

I

K.____

7

I

*

Figum 16 Conament Enginering Tmeline

I

K____

APPENDIX B: RELEVANT LITERATURE

Many of the recommended design principles and supply chain concepts are based upon existing research.This section describes several sources of knowledge on the topics relevant to this thesis. The reader isencouraged to consult these sources for more information on Design for Manufacturability, Supply ChainManagement, and Organizational Learning, since all of these are useful resources for anyone engaged inconcurrentengineering and product development.

DFM

Boothroyd and Dewhurst (1983) did a great deal of groundbreaking work in Design for Assembly. Theirresearch resulted in several basic principles for designing parts to simplify the assembly operation. They alsodeveloped tools for evaluating the ease of assembly of a particular design.

There are similar tools for evaluating the ease of manufacturing a design. Separate sets of principles arewritten for different manufacturing processes, some of which are included in Appendix E. For example, indesigning a part to be cast, it is generally best to avoid sharp corners, abrupt changes in thickness, andundercuts, and to let cross-sectional area decrease with increasing distance from the gates, so that material willnot be restricted before it has filled the cavity. The Design for Manufacturability Handbook (Bralla, 1998) isa collection of such principles in a single text.

MANUFACTURING TECHNOLOGIES

A basic understanding of the processes used to manufacture precision cast parts was obtained from generalhandbooks. Kalpakjian (1995) briefly describes most of the relevant operations in sufficient detail to allowthe reader to get an appreciation for the physics involved. The text includes articles on investment casting (p.306), hot isostatic pressing (p. 510), electrical-discharge machining (p. 836), electro-chemical machining (p.832), laser drilling (p. 840), and coating (p. 996). A more thorough treatment of each can be found in theASM Handbook (1988).

SUPPLY CHAIN MANAGEMENT

Fine (1998) emphasizes the importance of supply chain design as a core competence and the only trulysustainable source of competitive advantage. He examines companies in "high clockspeed" industries(frequent organizational changes, new product introductions, etc.) to gain insight into the principles of supplychain management for industries of all clockspeeds. He draws the analogy to fruitflies, which are studied ingenetics because of their short life cycle. Several generations of fruitflies can be observed in the laboratorysetting. The observations made can be generalized to species with life cycles that are much too long toobserve.

By observing such "fruitfly" industries as personal computers and multimedia entertainment, Fine makesseveral observations about the nature of changes in industries over time. One important tendency is forindustries to oscillate between a horizontal structure and vertical integration along a path Fine calls a double-helix. Figure 17 illustrates the difference between vertical and horizontal industries and between integral andmodular product architecture. Figure 18 (Fine 1998, p. 49) lists the forces that drive industries back and forthbetween vertical and horizontal structure.

- 57 -

Component 1 Firm A Firm B Firm C

Component 2 Firm D FirE

Component 3 Firm Firm Firm Firm FirmF G H I

Component 4 Firm K Firm L FirM

Horizontal Industry, Modular Product Vertical Industry, Integral Product

Figure 17 Horizontal modular structure s. wrtical integral

Niche Integral Modular Technicalcompetitors product, Product, adcances

vertical horizontalindustry industry

High Supplierdimensional marketcomplexity power

Pressure to Pressure toOrganizational disintegrate integrate Proprietary

rigidities system----- profitability

Figure 18 The double helix of oscillation in industry structure and product architectum

Fine asserts that, because industries and products are constantly changing, competitive advantage istemporary. At best, the only sustainable advantage is having the ability to manage knowledge across thesupply chain. This meta-competency of supply chain design must be integrated with product and processdesign in what Fine calls "Three-dimensional concurrent engineering" (3DCE).

ORGANIZATIONAL LEARNING

Senge (1994) builds a framework for learning organizations based on the experience of several companies.He suggests that the fundamental requirement for learning organizations is a change in thinking. Rather thanseeing oneself as a powerless victim of circumstances, one should see the part one plays in the larger system,of which one is an element. Senge outlines five "disciplines" for an effective learning organization:

1) Personal Mastery - commitment of the individuals to a group goal and self-improvement

2) Mental Models - assumptions, world view, learning to recognize one's own, and sharingmodels with others.

3) Shared Vision - translating individual vision into shared vision, not dictating.

4) Team Learning - a team's ability to improve performance by working together over time andto achieve a higher level of competence than any individual could

58 -

Firm A Firm B Firm C

m

J

m

5) Systems thinking - understanding interactions and system dynamics

Of particular interest are the basic principles of system dynamics. Senge lists several system archetypes, suchas balancing loops with delay, limits to growth, shifting the burden, eroding goals, escalation, tragedy of the

commons, etc., which can be found in many business systems. The learning model in Section 3 is a verysimple system, which includes growth and balancing loops. Appendix C explains the symbols used in the

model's diagrams. Appendix D lists the details of the model.

- 59 -

APPENDIX C: CAUSAL LOOP DIAGRAMS

Complex dynamic systems can be modeled using only a few simple components and establishing causalrelationships between them. Figure 19 shows a simple causal loop diagram and its basic elements. Variablescan be constants or functions of other variables. Arcs between variables indicate that one variable is afunction of the other, a causal relationship. A plus or minus symbol near the head of the arrow indicates therelationship between the two variables. If the sign is positive, then as one variable increases, the other tendsto increase as well. If the sign is negative, then as one tends to increase, the other tends to decrease.

Variable c

Source Sink

F71w in k Flow out

Figure 19 The basic componmts ofa causal loop diagran

There are two special types of variables: stocks and flows. A flow is a variable that happens to feed or drain astock. Flows can be constants or functions of other variables. A stock is strictly a function of those flowsthat feed or drain it. Formally, a stock is the integral of the sum of incoming flows minus the sum ofoutgoing flows. A bathtub could be modeled as a stock of water where the faucet allows water to flow in at acertain rate and the drain allows water to flow out at another rate. Sources and sinks provide a simple way tolimit the scope of the model. Each has limitless capacity and basically serves to terminate a flow withoutspecifying an additional stock from which the flow draws or into which the flow drains.

Such systems can be modeled after the relationships between variables are formulated and initial conditionsare specified. The system model presented in this thesis was simulated using VensimPLE32 Version 3.OD1.The software performs a discrete-time simulation by calculating the values of each variable once for everytime increment. The values of any variables can then be plotted to allow the user to observe trends.

- 60 -

APPENDIX D: A MODEL OF DFM LEARNING AND ITS COST IMPLICATIONS

Figure 20 shows all the variables needed to run the simulation used to draw the conclusions in section 3. The

following formulation explains the meaning of each variable and some assumptions.

Initial DFMRetained +

itial SUTA learningitial Product Tech +

D

DFM+ DFM Learning

loopLearning

rate

ManufacturabilityTechnology slI

+ Knowledge 1000/1Management Manufact

Effectiveness Tech WorsDevelopment Eng.

Ra fA per eng.-hr. DRate of

advaning +

techology <Projects p

Rate of -advancingstate of the--. echnology g

art +

Wors

feed

ManufaG

urable

st casehrs. forFM

er month>

ntion Projects per month N-, Vfction Cost of Capital of cost stream

future ++ Quality of payment <Time>

back 4-communication <TIME STEP>with suppliers +

Worst casdelivery dela

cturability penalty

ap Worst casescrap cost +

Delivery+ Penalties

Scrap/+ Rework

Engineering costTime

+ improving M TotalDFM + Engineering + +

Engineering + Time Cost per Projecttime -V +

developing +technology

+ngineering Engineerin

Cost per + costap hu

+ Performance

t case performance penalty + penalties

Figure 20 Causal loop diagram of complete DFM leaming mcdel

MODEL FORMULATION

(01) "100% Manufacturable"=1

Units: Dimensionless

The maximum value of manufacturability.

(02) Cost of Capital=0 .1/12

Units: Dimensionless

Interest rate that determines the opportunity cost of capital.

(03) Cost per Project=Delivery Penalties+Engineering cost+Performance

penalties+"Scrap/ Rework cost"

Units: DollarsThe average cost per new product

- 61 -

in

In

(04) Delivery Penalties=

Manufacturability Gap*Worst case delivery delay penaltyUnits: Dollars

Penalty incurred per project for late delivery.

(05) DFM= INTEG (Learning rate,

Initial DFM)

Units: Dimensionless

Learned ability of engineering to design for manufacturability.

(06) DFM feedback=

Manufacturability Gap*Quality of communication withsuppliers

Units: Dimensionless

Information received by engineering from manufacturing on themanufacturability of the design.

(07) Engineering cost=

Engineering Cost per hour*Total Engineering TimeUnits: Dollars

The total engineering cost per project.

(08) Engineering Cost per hour=

100Units: Dollars/hr

Cost of one hour of one engineer's time.

(09) Engineering time developing technology=

5120Units: hr

Engineer-hours spent developing product technology per project

(10) Engineering Time improving DFM=

Manufacturability Gap*"Worst case Eng. hrs. for DFM"Units: hr

Amount of engineering time required to make designmanufacturable.

(11) FINAL TIME = 100

Units: Month

The final time for the simulation.

(12) Initial DFM=

0Units: Dimensionless

Value of DFM at time=0

- 62 -

(13) Initial Product Tech=

1

Units: Dimensionless

Value of Product Tech. at time=0

(14) Initial SOTA=

1

Units: Dimensionless

Value of SOTA at time=0

(15) INITIAL TIME = 0Units: Month

The initial time for the simulation.

(16) Knowledge Management Effectiveness=

0.75Units: Dimensionless

The fraction of relevant DFM knowledge that is successfully

retreived and applied to new designs.

(17) Learning rate=

Retained learning-Technology slip

Units: 1/Month

The increase in the ability of the design organization to

produce manufacturable designs.

(18) Manufacturability=

DFM*Knowledge Management Effectiveness

Units: Dimensionless

The ease with which designs can be manufactured.

(19) Manufacturability Gap=

"100% Manufacturable" -Manufacturability

Units: Dimensionless

The amount by which manufacturability could improve.

(20) NPV of cost stream= INTEG (

NPV of future payment,

0)

Units: Dollars

The total net present value of all future costs within the time

horizon.

(21) NPV of future payment=

Cost per Project*Projects per month/(1+Cost of

Capital)^ (Time/TIME STEP)

Units: Dollars/Month

- 63 -

(22) Performance penalties=

Technology gap*Worst case performance penalty

Units: Dollars

The cost of poor product performance due to lost sales andperformance-based price penatlies.

(23) Projects per month=

0.15Units: 1/Month

Number of new projects started per month, assumed two per year.

(24) Quality of communication with suppliers=

0.75Units: Dimensionless

Fraction of design-related manufacturing problems communicatedby supplier.

(25) Rate of advancing state of the art=0.1

Units: 1/Month

The percent of DFM knowledge that becomes obsolete due toadvances in product technology.

(26) Rate of advancing techology=Engineering time developing technology*"Tech Development

per eng.-hr."*Projects per month

Units: 1/Month

The percent increase in product technology level per unit time

(27) Retained learning=

DFM feedback*retention fraction

Units: 1/Month

Amount of feedback actually retained for future productdevelopment cycles.

(28) retention fraction=

0.75Units: 1/Month

Fraction of feedback actually retained for future productdevelopment cycles.

(29) SAVEPER = 1Units: Month

The frequency with which output is stored.

(30) "Scrap/ Rework cost"=

Manufacturability Gap*Worst case scrap cost

- 64 -

Units: Dollars

Cost of scrap and rework per project.

(31) "Tech Development per eng.-hr."=0.0001

Units: 1/hr

The rate at which technology development proceeds perengineer-hour invested.

(32) Technology gap=(Rate of advancing state of the art-Rate of advancing

techology)/Rate of advancing state of the art

Units: Dimensionless

The amount by which the company's product technology lags the

state of the art.

(33) Technology slip=DFM*Rate of advancing techology

Units: 1/MonthThe amount by which the value of DFM knowledge is reduced

because of increases in the level of product

technology.

(34) TIME STEP = 1

Units: MonthThe time step for the simulation.

(35) Total Engineering Time=Engineering time developing technology+Engineering Time

improving DFMUnits: hr

Total engineer-hours spent per project

(36) Worst case delivery delay penalty=

4e+007Units: Dollars

The penalty per project for delayed product delivery in theworst case, where the design is as difficult to

manufacture asimaginable, arbitrary figure assumed.

(37) "Worst case Eng. hrs. for DFM"=4000

Units: hrEngineering hours required to rework design to make it

manufacturable in the worst case, where the designrequires the

- 65 -

most modification imaginable, assumed to be one full-time

engineer dedicated to modifications for two years.

(38) Worst case performance penalty=le+007

Units: DollarsCost of lagging the state of the art through lost revenues and

performance price penalties in the worst caseimaginable,

arbitrary figure assumed.

(39) Worst case scrap cost=le+007

Units: DollarsCost of scrap and rework per project in the case of the worst

manufacturability imaginable, arbitrary figureassumed.

(01) "100% Manufacturable"=

1Units: DimensionlessThe maximum value of manufacturability.

(02) Cost of Capital=0 .1/12

Units: DimensionlessInterest rate that determines the opportunity cost of capital.

(03) Cost per Project=Delivery Penalties+Engineering cost+Performance

penalties+"Scrap/ Rework cost"Units: DollarsThe average cost per new product

(04) Delivery Penalties=

Manufacturability Gap*Worst case delivery delay penaltyUnits: DollarsPenalty incurred per project for late delivery.

(05) DFM= INTEG (Learning rate,

Initial DFM)Units: DimensionlessLearned ability of engineering to design for manufacturability.

(06) DFM feedback=

-66 -

Manufacturability Gap*Quality of communication with

suppliersUnits: Dimensionless

Information received by engineering from manufacturing on the

manufacturability of the design.

(07) Engineering cost=Engineering Cost per hour*Total Engineering Time

Units: Dollars

The total engineering cost per project.

(08) Engineering Cost per hour=

100

Units: Dollars/hr

Cost of one hour of one engineer's time.

(09) Engineering time developing technology=5120

Units: hr

Engineer-hours spent developing product technology per project

(10) Engineering Time improving DFM=

Manufacturability Gap*"Worst case Eng. hrs. for DFM"

Units: hr

Amount of engineering time required to make design

manufacturable.

(11) FINAL TIME = 100

Units: MonthThe final time for the simulation.

(12) Initial DFM=

0Units: Dimensionless

Value of DFM at time=0

(13) Initial Product Tech=

1Units: Dimensionless

Value of Product Tech. at time=0

(14) Initial SOTA=1

Units: Dimensionless

Value of SOTA at time=0

(15) INITIAL TIME = 0Units: Month

- 67 -

The initial time for the simulation.

(16) Knowledge Management Effectiveness=

0.75Units: Dimensionless

The fraction of relevant DFM knowledge that is successfully

retreived and applied to new designs.

(17) Learning rate=

Retained learning-Technology slipUnits: 1/Month

The increase in the ability of the design organization toproduce manufacturable designs.

(18) Manufacturability=

DFM*Knowledge Management EffectivenessUnits: Dimensionless

The ease with which designs can be manufactured.

(19) Manufacturability Gap=

"100% Manufacturable" -Manufacturability

Units: Dimensionless

The amount by which manufacturability could improve.

(20) NPV of cost stream= INTEG (NPV of future payment,

0)Units: Dollars

The total net present value of all future costs within the timehorizon.

(21) NPV of future payment=

Cost per Project*Projects per month/(l+Cost ofCapital)^(Time/TIME STEP)

Units: Dollars/Month

(22) Performance penalties=

Technology gap*Worst case performance penaltyUnits: Dollars

The cost of poor product performance due to lost sales andperformance-based price penatlies.

(23) Projects per month=

0.15Units: 1/Month

Number of new projects started per month, assumed two per year.

(24) Quality of communication with suppliers=

- 68 -

0.75Units: Dimensionless

Fraction of design-related manufacturing problems communicated

by supplier.

(25) Rate of advancing state of the art=

0.1

Units: 1/Month

The percent of DFM knowledge that becomes obsolete due to

advances in product technology.

(26) Rate of advancing techology=

Engineering time developing technology*"Tech Development

per eng.-hr."*Projects per month

Units: 1/Month

The percent increase in product technology level per unit time

(27) Retained learning=

DFM feedback*retention fraction

Units: 1/Month

Amount of feedback actually retained for future product

development cycles.

(28) retention fraction=

0.75Units: 1/Month

Fraction of feedback actually retained for future product

development cycles.

(29) SAVEPER = 1

Units: Month

The frequency with which output is stored.

(30) "Scrap/ Rework cost"=

Manufacturability Gap*Worst case scrap cost

Units: Dollars

Cost of scrap and rework per project.

(31) "Tech Development per eng.-hr."=

0.0001

Units: 1/hr

The rate at which technology development proceeds per

engineer-hour invested.

(32) Technology gap=

(Rate of advancing state of the art-Rate of advancing

techology)/Rate of advancing state of the art

Units: Dimensionless

- 69 -

The amount by which the company's product technology lags thestate of the art.

(33) Technology slip=

DFM*Rate of advancing techology

Units: 1/Month

The amount by which the value of DFM knowledge is reduced

because of increases in the level of producttechnology.

(34) TIME STEP 1

Units: Month

The time step for the simulation.

(35) Total Engineering Time=

Engineering time developing technology+Engineering Timeimproving DFM

Units: hr

Total engineer-hours spent per project

(36) Worst case delivery delay penalty=

4e+007Units: Dollars

The penalty per project for delayed product delivery in theworst case, where the design is as difficult to

manufacture as

imaginable, arbitrary figure assumed.

(37) "Worst case Eng. hrs. for DFM"=4000

Units: hr

Engineering hours required to rework design to make itmanufacturable in the worst case, where the design

requires the

most modification imaginable, assumed to be one full-time

engineer dedicated to modifications for two years.

(38) Worst case performance penalty=

le+007Units: Dollars

Cost of lagging the state of the art through lost revenues andperformance price penalties in the worst case

imaginable,

arbitrary figure assumed.

(39) Worst case scrap cost=

le+007

-70-

Units: Dollars

Cost of scrap and rework per project in the case of the worst

manufacturability imaginable, arbitrary figureassumed.

(01) "100% Manufacturable"=1

Units: DimensionlessThe maximum value of manufacturability.

(02) Cost of Capital=0.1/12

Units: Dimensionless

Interest rate that determines the opportunity cost of capital.

(03) Cost per Project=

Delivery Penalties+Engineering cost+Performancepenalties+"Scrap/ Rework cost"

Units: DollarsThe average cost per new product

(04) Delivery Penalties=Manufacturability Gap*Worst case delivery delay penalty

Units: DollarsPenalty incurred per project for late delivery.

(05) DFM= INTEG (Learning rate,

Initial DFM)Units: DimensionlessLearned ability of engineering to design for manufacturability.

(06) DFM feedback=Manufacturability Gap*Quality of communication with

suppliersUnits: Dimensionless

Information received by engineering from manufacturing on themanufacturability of the design.

(07) Engineering cost=Engineering Cost per hour*Total Engineering Time

Units: DollarsThe total engineering cost per project.

(08) Engineering Cost per hour=100

Units: Dollars/hrCost of one hour of one engineer's time.

-71 -

(09) Engineering time developing technology=

5120

Units: hr

Engineer-hours spent developing product technology per project

(10) Engineering Time improving DFM=

Manufacturability Gap*"Worst case Eng. hrs. for DFM"Units: hr

Amount of engineering time required to make design

manufacturable.

(11) FINAL TIME = 100

Units: Month

The final time for the simulation.

(12) Initial DFM=

0Units: Dimensionless

Value of DFM at time=0

(13) Initial Product Tech=

1

Units: Dimensionless

Value of Product Tech. at time=0

(14) Initial SOTA=

1

Units: Dimensionless

Value of SOTA at time=0

(15) INITIAL TIME = 0Units: Month

The initial time for the simulation.

(16) Knowledge Management Effectiveness=

0.75Units: Dimensionless

The fraction of relevant DFM knowledge that is successfullyretreived and applied to new designs.

(17) Learning rate=

Retained learning-Technology slip

Units: 1/Month

The increase in the ability of the design organization to

produce manufacturable designs.

(18) Manufacturability=

-72 -

DFM*Knowledge Management Effectiveness

Units: Dimensionless

The ease with which designs can be manufactured.

(19) Manufacturability Gap=

"100% Manufacturable" -Manufacturability

Units: Dimensionless

The amount by which manufacturability could improve.

(20) NPV of cost stream= INTEG (

NPV of future payment,

0)Units: Dollars

The total net present value of all future costs within the time

horizon.

(21) NPV of future payment=

Cost per Project*Projects per month/(1+Cost of

Capital)^(Time/TIME STEP)

Units: Dollars/Month

(22) Performance penalties=

Technology gap*Worst case performance penalty

Units: Dollars

The cost of poor product performance due to lost sales and

performance-based price penatlies.

(23) Projects per month=

0.15

Units: 1/Month

Number of new projects started per month, assumed two per year.

(24) Quality of communication with suppliers=

0.75Units: Dimensionless

Fraction of design-related manufacturing problems communicated

by supplier.

(25) Rate of advancing state of the art=

0.1

Units: 1/Month

The percent of DFM knowledge that becomes obsolete due to

advances in product technology.

(26) Rate of advancing techology=

Engineering time developing technology*"Tech Development

per eng.-hr."*Projects per month

Units: 1/Month

- 73 -

The percent increase in product technology level per unit time

(27) Retained learning=

DFM feedback*retention fraction

Units: 1/Month

Amount of feedback actually retained for future product

development cycles.

(28) retention fraction=

0.75Units: 1/Month

Fraction of feedback actually retained for future product

development cycles.

(29) SAVEPER = 1Units: Month

The frequency with which output is stored.

(30) "Scrap/ Rework cost"=

Manufacturability Gap*Worst case scrap costUnits: Dollars

Cost of scrap and rework per project.

(31) "Tech Development per eng.-hr."=

0.0001

Units: 1/hr

The rate at which technology development proceeds perengineer-hour invested.

(32) Technology gap=

(Rate of advancing state of the art-Rate of advancingtechology)/Rate of advancing state of the art

Units: Dimensionless

The amount by which the company's product technology lags thestate of the art.

(33) Technology slip=

DFM*Rate of advancing techology

Units: 1/Month

The amount by which the value of DFM knowledge is reducedbecause of increases in the level of product

technology.

(34) TIME STEP = 1Units: Month

The time step for the simulation.

(35) Total Engineering Time=

-74-

Engineering time developing technology+Engineering Time

improving DFM

Units: hr

Total engineer-hours spent per project

(36) Worst case delivery delay penalty=

4e+007

Units: Dollars

The penalty per project for delayed product delivery in the

worst case, where the design is as difficult to

manufacture as

imaginable, arbitrary figure assumed.

(37) "Worst case Eng. hrs. for DFM"=

4000

Units: hr

Engineering hours required to rework design to make it

manufacturable in the worst case, where the design

requires the

most modification imaginable, assumed to be one full-

time

engineer dedicated to modifications for two years.

(38) Worst case performance penalty=

le+007Units: Dollars

Cost of lagging the state of the art through lost revenues and

performance price penalties in the worst case

imaginable,arbitrary figure assumed.

(39) Worst case scrap cost=

le+007Units: Dollars

Cost of scrap and rework per project in the case of the worst

manufacturability imaginable, arbitrary figure

assumed.

- 75 -

APPENDIX E: MACHINING COST ESTIMATION MODELS

The following formulae are included as examples of how manufacturing costs can be estimated in the designphase. While these calculations could be quite cumbersome if used manually, CAD software offers thepossibility of automating them in design review mode. These tools can then be used to support designdecisions. The basic cost function is the product of the duration of the operation and the cost per unit timeof machine use (including labor and overhead), which can be estimated or based upon figures from themanufacturer.

LASER DRILLING

The following energy balance relates the cutting time t of a line of length I with a laser of power P (Powell1989):

(P - b)t(x/100)=Ectldk + tndk/2(A+B+C)

where:

b = laser power transmitted through the cut zone without interaction with the cut front.

x = the absorptivity of the cut zone expressed as a percentage.

Ecut = specific energy needed to melt and remove one unit volume of material from the cut zone.

d = material thickness

k = kerf width

A = Conductive loss function.

B = Radiative loss function.

C = Convective loss function.

These terms are clarified in the article. However, it is likely that information specific to the relevantequipment and material can be obtained from the manufacturer.

ELECTRIC DISCHARGE MACHINING

For both EDM and ECM, the basic formula for the machining time is

t = (V/Rmr)

where:

V = Volume of material to be removed

Rmr = material removal rate

While formulae are presented here to help estimate the material removal rate, this value is best obtained fromthe manufacturer.

- 76 -

Springbom (1967, 111) uses the following to calculate material removal rate:

Rw = 2.43Mw- 2 3

where:

Rw = Average metal removal rate from workpiece (in3/amp-min x 104)

Mw = Melting point of workpiece ( C)

The removal rate Rm- is, therefore, the product of Rw and the current used.

ELECTRO-CHEMICAL MACHINING

Springborn (1967, 41) gives the following formula for ECM:

s = [(N/n) x (1/d) x (1/95,500) x y]

where:

d = Density (g/cm3)

y = Current efficiency

I = Current

N = Atomic weight of material

N = Valence of material

s = Specific removal rate (cm3/amp-sec.)

Rm, = sI

Again, this formula can be used to estimate the material removal rate, but it is best to get it from themanufacturer.

- 77 -

APPENDIX F: OVERLAPPING OPTIMIZATION MODEL

Krishnan (1993) gives the following formulation to optimize the timing of design freezes, iteration start timesand the number of iterations, given the evolution and sensitivity of the upstream and downstream activities.

Minimize X

Subject to

tF tAf

ti ti-I + di1i

to tAs

tAs < ti <F 1

tn tF

X = tn + di

Ax(ti,ti) = (bin - ain) (ej-ei)/2

di = D(Ax(thr, ti))

where

= 1,2,... ,n

= 1,2,... ,n-1

= Start time of ith iteration (decision variable) i = 0,1,2,... ,n

= Duration of ith iteration (variable) i = 0,1,2,... ,n

= Duration of planned iteration (input)

= Start time of upstream activity (taken as origin of the time scale)

= Nominal Finish time of up stream activity (input)

= Advance freeze time of exchanged information (decision variable)

= Product Development Lead Time

= Number of iterations subsequent to the planned iteration (decision variable)

= The sensitivity funtion

- 78 -

ti

d~i

do

tAs

tAf

tF

n

(D

APPENDIX G: DEFINITIONS

Term Definition

CE Concurrent Engineering

DFM Design for manufacturability, a methodology or set of principles to help designers consider theimpact of design decisions on the cost of manufacturing when developing products.

ECM Electrochemical Machining, a method of material removal that operates by the same process aselectroplating, but in reverse.

EDM Electric Discharge Machining, a process of material removal using a dielectric medium and ashaped electrode to generate electric arcs that vaporize material locally

GT Gas Turbine

NCR Nonconformance Report

PTFE Polytetrafluoroethylene, commonly called Teflon®, a registered trademark of DuPont

NPV Net Present Value, the current value of a set of future transactions assuming that money losesvalue with time at an exponential rate, the cost of capital

- 79 -