Mechanical Assemblies Their Design, Manufacture, and Role in Product Development Daniel E. Whitney Massachusetts Institute of Technology New York Oxford OXFORD UNIVERSITY PRESS 2004 MECHANICAL ASSEMBLIES Their Design, Manufacture, and Role in Product Development Oxford University Press Oxford New York Auckland Bangkok Buenos Aires Cape Town Chennai Dar es Salaam Delhi Hong Kong Istanbul Karachi Kolkata Kuala Lumpur Madrid Melbourne Mexico City Mumbai Nairobi Sao Paulo Shanghai Taipei Tokyo Toronto Copyright © 2004 by Oxford University Press, Inc. Published by Oxford University Press, Inc. 198 Madison Avenue, New York, New York 10016 www.oup.com Oxford is a registered trademark of Oxford University Press All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior permission of Oxford University Press. The information, methods, and any software or algorithms in this book and on the accompanying CD-ROM are believed to be accurate but are presented for the purpose of education only and should not be relied on for engineering calculations for any specific design or product. The author and publisher make no warranty of any kind, express or implied, with regard to the contents of this book. If expert advice is needed, the services of a competent professional should be obtained. Library of Congress Cataloging-in-Publication Data Whitney, Daniel E. Mechanical assemblies: their design, manufacture, and role in product development/by Daniel E. Whitney. p. cm. Includes bibliographical references and index. ISBN 0-19-515782-6 1. Production engineering. 2. Design, Industrial. I. Title. TS171.4.W48 2004 658.5'752-dc22 Printing number: 987654321 Printed in the United States of America on acid-free paper 2003066170 PREFACE AIMS OF THIS BOOK The overt aim of this book is to present a systematic approach to the design and production of mechanical assemblies. It should be of interest to engineering pro- fessionals in the manufacturing industries as well as to post-baccalaureate students of mechanical, manufactur- ing, and industrial engineering. Readers who are interested in logistical issues, supply chain management, product architecture, mass customization, management of vari- ety, and product family strategies should find value here because these strategies are enabled during assembly design and are implemented on the assembly floor. The approach is grounded in the fundamental engineer- ing sciences, including statics, kinematics, geometry, and statistics. These principles are applied to realistic exam- ples from industrial practice and my professional experi- ence as well as examples drawn from student projects. 1 It treats assembly on two levels. Assembly in the small deals with putting two parts together. These are the basic processes of assembly, much as raising a chip is a funda- mental process of machining. Assembly in the large deals with design of assemblies so that they deliver their re- quired performance, as well as design and evaluation of assembly processes, workstations, and systems. The sequence of chapters follows the three themes in the book's title: design of assemblies, manufacture of assemblies, and the larger role of assemblies in product development. Assembly is the capstone process in discrete parts prod- uct manufacturing. Yet there is no book that covers these themes. This is very surprising because there are many books about the design and manufacture of machine ele- ments like shafts and gears. But these items do not do any- thing by themselves. Only assemblies of parts actually do anything, except for a few one-part products like baseball bats and beer can openers. Assemblies are really the things that are manufactured, not parts. Customers appreciate the things products do, not the parts they are made of. The lack of books on assemblies is reflected in many companies where it is easy to find job descriptions corre- sponding to the design of individual parts but hard to find job descriptions corresponding to design of assemblies. As one engineer told me, "The customer looks at the gap between the door and the fender. But it's an empty space and we don't assign anyone to manage empty spaces." There are also many books about tolerances and sta- tistical process control for the manufacture of individual parts, but little or nothing about assembly process capa- bility or the design of assembly equipment to meet a par- ticular level of capability, however it is defined. There are, in addition, many fine books about balancing assembly lines and predicting their throughput, given that there is a competently designed assembly ready to be assembled. But what is a competently designed assembly and how would we know one if we saw one? This book is directed at that question. A deeper aim of the book is to show how to apply prin- ciples from system engineering to design of assemblies. This is done by exploiting the many similarities between systems in general and assemblies in particular. Students who learn about parts but not about assemblies never get XIX 1 Many of my curious experiences in professional practice are in- cluded in footnotes or used as quotes at the beginning of many chapters. XX PREFACE a high-level view of how parts work together to create function, and thus they do not know how to design parts that are intended to contribute to a function in conjunction with other parts. For this reason, they design parts as in- dividual items and are satisfied when they think they have done their individual job well. They are as disconnected from the product they are designing as is the assembly line worker who installs the same part for thirty years without knowing what product is being produced. Products and companies can fail for lack of anyone who understands how everything is supposed to work together. The systems focus of the book is part of a trend at MIT to complement traditional engineering science with integrative themes that unite engineering with economic, managerial, and social topics. OUTLINE OF THIS BOOK Chapter 1 provides a discussion about what an assembly is and why it is important. Chapters 2 through 8 deal with the design of assemblies, including a requirements-driven approach to designing assem- blies that is based on mathematical and engineering principles, a theory of kinematic assemblies 2 that shows how to specify and tolerance assemblies so that they deliver geometrically defined customer requirements, the method of key characteristics for defining the important dimensions of an assembly, and the datum flow chain technique for designing assem- blies to achieve their key characteristics. Chapters 9 through 11 deal with the basic processes of assembly, including how to describe the motions that parts undergo during assembly operations and what the conditions are under which a part mating attempt will or will not be successful. Chapters 12 through 18 extend the scope of inquiry to include manufacturing methods and systems and the role of assembly in product development. Important topics in 2 As explained more completely in Chapter 4, a kinematic assembly is one that can be assembled without applying force or storing energy in the parts. these chapters include assembly in the large, a view of how product function and business issues each can be viewed through the prism of assembly, how to analyze an existing assembly and perform a design for assembly (DFA) analysis, an exploration of product architecture, including its relationships to business strategy and design for assembly, design of assembly systems and workstations, and economic analysis of assembly systems. A compact disc accompanies this book. The CD-ROM contains an additional chapter, Chapter 19, which is a com- plete case study that applies the book's methods to an air- craft structural subassembly. In addition, the CD-ROM contains supporting material such as chapter appendixes, student class project reports, a professional consulting re- port, software, and MATLAB routines that duplicate ex- amples and methods in Chapters 3, 4, 5, 6, 16, 18, and 19. HOW THE COURSE HAS BEEN TAUGHT The material in the book has been presented to MIT grad- uate students for several years. The explicit prerequisites include linear algebra (to help the students with the matrix math) and applied mechanics (to provide a background in statics and statically determinate structures). There is no prerequisite for a knowledge of probability and statistics, even though the treatment of tolerancing makes use of those ideas and presents the basics in passing. Neverthe- less, one student emphasized to me the huge paradigmatic difference between the usual way of teaching design (there is one answer) and the fact that we live in a stochastic world where designs and objects are really members of histograms. Until he took this course, he had seen only the former, never the latter. Implicit prerequisites that make it easier for students to grasp the concepts include some experience in mechanical design, some work in industry, and an ability to make reasonably realistic perspective or isometric sketches of mechanical parts and simple assemblies. Raw ability to manipulate equations or computer simulations will not be enough to either teach or learn this material. The class taught by me meets twice a week for 1.5 hours, for a total of 25 class sessions. Each session focuses on PREFACE XXI one chapter, although several chapters, such as those cov- ering constraint, variation, datum flow chain, and prod- uct architecture are conceptually challenging and require two or three class sessions each. Homework assignments provide practice with the concepts. In some cases, consid- erable class time is devoted to discussing the homework. In addition to class sessions and traditional homework, students form groups with four to six members and do a semester-long project. Students with work experience enjoy telling the class how course material compares with corresponding meth- ods at their current or previous employers. I and my students value contributions from the class, which are en- couraged throughout the semester. Some of these contri- butions have enriched my knowledge and have made their way into the book. Throughout the book, portions of student project work are used as examples to illustrate the concepts as well as to showcase the accomplishments of the students and encourage others to emulate them. POSSIBLE TEACHING APPROACHES My MIT classes consist of both traditional mechanical engineering students and students pursuing MBAs with an engineering emphasis. Since the engineering content, such as part mating physics and tolerance chains, appeals to the engineering students while the business content, such as product architecture and supply chains, appeals to the MBAs, each group grumbles a bit about being taught the other group's favored material. I strive to convince each group that the other's favorite material is important for them to understand, because that provides the integrated system-level view. Nevertheless, teachers using this book may wish to par- tition the material cleanly into engineering focus and man- agement focus semesters or quarters. To aid this, here are a few paths through the chapters for various emphases (all paths start with the Preface and Chapter 1, which are therefore not listed): Engineering design focus: Chapters 2-8, 10, 11, 13, 15 Industrial/manufacturing engineering focus: Chap- ters 5-7, 9, 15-18 Engineering management focus: Chapters 12, 14, 18, 19 Bottom-up sequence from parts to systems: Chap- ters 9, 13, 10, 11, 2–8, 12, 14–19. In the bottom-up sequence, which I use, not all chapters are taught each semester and not all get equal time or emphasis. ACKNOWLEDGMENTS I have benefited during preparation of this book, and throughout my career, from many people, to whom I am deeply grateful. If there are any errors in this book, they are mine and not those of any person who contributed ma- terial or ideas. I also apologize if anyone has been omitted from the following list. Charles Stark Draper Laboratory colleagues: Mr. James L. Nevins, Dr. Thomas L. De Fazio, Mr. Alexander C. Edsall, Mr. Richard E. Gustavson, Mr. Richard W. Metzinger, and Mr. Donald S. Seltzer. Our work together over more than twenty years formed my understanding and appreciation of assembly as an intellectual focus and provided the backbone of many of the book's chapters. Some of these chapters are updates of chapters in our ear- lier book Concurrent Design of Products and Processes, New York, McGraw-Hill, 1989. I also wish to thank cur- rent and former Draper colleagues Dr. J. Edward Barton, Prof. Samuel H. Drake, Mr. Richard R. Hildebrant, Mr. Michael P. Hutchins, Dr. Daniel Killoran, Mr. Anthony S. Kondoleon, Mr. Steven C. Luby, Prof. Thomas J. Peters, Mr. Raymond Roderick, Mr. Jonathan M. Rourke, Dr. Sergio N. Simunovic, Mr. Thomas M. Stepien, the late Mr. Paul C. Watson, and Mr. E. Albert Woodin for their contributions to our collective work. MIT colleagues and programs: Mr. Martin Anderson, Dr. Don P. Clausing, Dr. George L. Roth, Professors Edward F. Crawley, Steven D. Eppinger, Charles H. Fine, Daniel Frey, David C. Gossard, Stephen C. Graves, Christopher L. Magee, Joel Moses, Daniel Roos, Warren P. Seering, Alex H. Slocum, Nam P. Suh, James M. Utterback, and David Wallace; the Center for Innovation in Product Development, the International Motor Vehicle Program, the Leaders for Manufacturing Program, the System Design and Management Program, and the Ford- MIT Research Alliance. These colleagues and programs provided intellectual stimulation, encouragement; finan- cial support, and contact with companies and real indus- trial problems. XXII PREFACE Professional colleagues at universities and industrial companies: Brigham Young University: Prof. Ken Chase; Carnegie-Mellon University: Professors Susan Finger, David Hounshell, and Matthew Mason; Cranfield Univer- sity: Prof. Tim Baines and Dr. Ip-shing Fan; IPK Berlin: Prof. Dr Ing. Frank-Lothar Krause; Lancaster Univer- sity: Prof. Michael French; l'Université de Franche-Comté: Professors Alain Bourjault and Jean Michel Henrioud; University of Michigan: Professors Walton Hancock, Jack Hu, and Jeffrey Liker; Oxford University: Prof. J. Michael Brady; Stanford University: Professors Mark Cutkosky, Daniel De Bra, and Bernard Roth; Technion: Prof. Dan Braha; USC Information Sciences Institute: Dr. Peter Will; University of Naples Federico II: Professors Francesco Caputo and Salvatore Gerbino; NIST: Dr. Michael Pratt, Dr. Ram Sriram, and Dr. Michael Wozny; University of Pennsylvania: Professors Daniel M. G. Raff and Karl Ulrich; Purdue University: Professors Christoph Hoffmann and Shimon Nof; RPI: Professors Arthur and Susan Sanderson; University of Southern California: Prof. Ari Requicha; University of Tokyo: Professors Takahiro Fujimoto and Fumihiko Kimura; Virginia Polytechnic Institute: Prof. Robert Sturges; WZB Berlin: Dr. Ulrich Jürgens; Adept Technology: Mr. Brian R. Carlisle; Airbus: M. Bernard Vergne, Dr. Benoit Marguet; Analytics: Dr. Anna Thornton; Arvin-Meritor: Mr. John Grace; Boeing: Mr. Tim Copes, Mr. E. L. Helvig, Dr. Stephen Keeler, Dr. Alan K. Jones, Mr. Wencil McClenahan, Mr. Scott P. Muske, Mr. Frederick M. Swanstrom, Dr. Steve Woods; Boothroyd & Dewhurst: Prof. Geoffrey Boothroyd; The Budd Co.: Mr. John M. Vergoz; Cogni- tion: Mr. Michael Cronin; Daimler-Chrysler: Dr. Gustav Oiling; Denso Co. Ltd.: Mr. Koichi Fukaya; Eastman Kodak: Mr. Douglass Blanding, Mr. Jon Kriegel, and Dr. Randy Wilson; Fanuc Robotics: Dr. Hadi A. Akeel; Ford Motor Company: Mr. Robert Bonner, Mr. James Darkangelo, Dr. Shuh Liou, Mr. Ting Liu, Dr. Richard Riff, Dr. Agus Sudjianto, and Dr. Nancy Wang; General Motors: Mr. Charles Klein, Mr. Steven Holland; Hitachi, Ltd.: Mr. Toshijiro Ohashi; Lockheed-Martin: Ms. Linda B. Griffin, Mr. Randy Schwemmin; Munro and Asso- ciates: Mr. Sandy Munro; M. S. Automation: Dr. Mario Salmon; SDRC: Dr. Albert Klosterman; Telemechanique: Dr. Albeit Morelli; Toyota Motor Company: Dr. Christopher Couch; Vought: Mr. Cartie Yzquierdo. These individuals and their companies provided intellectual stimulation, gracious sharing of ideas, and crucial contact with real products and assembly processes to me and my students through summer internships and frequent visits. Students: Mr. Jeffrey D. Adams, Mr. Jagmeet Singh Arora, Dr. Timothy W. Cunningham, Mr. J. Michael Gray, Dr. Ramakrishna Mantripragada, Mr. Gaurav Shukla, and Mr. Andrew M. Terry. These key students developed much of the theory presented in the first eight chapters of this book. Students whose case studies provided important data and insights include Mrs. Mary Ann Anderson, M. Denis Artzner, Mr. Edward Chung, Mr. Gennadiy Goldenshteyn, Mr. J. Michael Gray, Mr. Brian Landau, Mr. Don Lee, Mr. Craig Moccio, Mr. Guillermo Peschard, Mr. Stephen Rhee, Mr. Tariq Shaukat, and Mr. Jagmeet Singh Arora. Current and former students who wrote im- portant tutorial software include Mr. Michael Hoag, Mr. J. Michael Gray, and Dr. Carol Ann McDevitt. Students whose class projects provided inspiring material of pro- fessional quality for the book are named in the chapters where their work appears. Colleagues and students who read part or all of the book and made valuable comments: Prof. J. T. Black, Prof. Geoffrey Boothroyd, Prof. Christopher L. Magee, Mr. Wesley Margeson, Mr. James L. Nevins, Mr. Stefan von Praun, Mr. Daniel Rinkevich, Mr. Thomas H. Speller, Jr., Prof. Herbert Voelcker, Dr. John Wesner, and Prof. Paul Wright. I also thank several anonymous re- viewers for extensive and important comments. Oxford University Press staff: Peter Gordon, Elyse Dubin, Danielle Christensen, and Brian Kinsey, whose help, forebearance, and enthusiasm are much appreciated. Copyright holders: Publitec S.r.l, publishers of As- semblaggio for many photographs; Sage Publications for many figures reprinted from Gustavson, R., Hennessey, M. J., and Whitney, D. E., "Designing Chamfers," Robotics Research, vol. 2, no. 4, pp. 3-18, 1983; ASME Interna- tional for many figures reprinted from Whitney, D. E., "Quasi-Static Assembly of Compliantly Supported Rigid Parts," ASME Journal of Dynamic Systems, Measurement and Control, vol. 104, pp. 65-77, 1982; Whitney, D. E., and Adams, J. D., "Application of Screw Theory to Con- straint Analysis of Assemblies Joined by Features," ASME Journal of Mechanical Design, vol. 123, no. 1, pp. 26–32, 2001; and Springer-Verlag for many figures reprinted from Whitney, D. E., Gilbert, O., and Jastrzebski, M., "Repre- sentation of Geometric Variations Using Matrix Trans- forms for Statistical Tolerance Analysis in Assemblies," PREFACE XXIII Research in Engineering Design, vol. 6, pp. 191-210, 1994; Mantripragada, R., and Whitney, D. E., "The Datum Flow Chain," Research in Engineering Design, vol. 10, pp. 150-165, 1998; and Whitney, D. E., Mantripragada, R., Adams, J. D., and Rhee, S. J., "Designing Assem- blies," Research in Engineering Design, vol. 11, pp. 229- 253, 1999; plus many others who are named in connec- tion with the specific items which they permitted to be reproduced. Funding agencies and respective program managers: U.S. Air Force Wright Laboratory/MTIA, Mr. George Orzel, Program Manager, contracts F33615-94-C-4428 and F33615-94-C-4429; the National Science Founda- tion grant DMI-9610163, Dr. George Hazelrigg, Program Manager, and Cooperative Agreement No. EEC-9529140, Dr. Fred Betz, Program Manager. Their support and en- couragement are gratefully acknowledged. My family: Dr. Cynthia K. Whitney, Mr. David C. Whitney, and Dr. Karl D. Whitney for love, tolerance, and specific intellectual contributions. This book is dedicated to them. THE CHAPTER-OPENING QUOTATIONS Most chapters begin with a quotation that is intended to convey the spirit of the material in the chapter. Every one of these quotations is real and was spoken to me. I have written them down and, in some cases, paraphrased or condensed them before placing them in the book. Where there was no suitable quotation, a chapter does without. Readers are invited to contribute candidate quotes for any chapter and to forward them to me. I will happily collect them and, if appropriate, use them with attribution, should there be a second edition of this book. CONTENTS l.A. Introduction 1 l.B. Some Examples 2 1.B.1. Stapler Tutorial 2 l.B.2. Assembly Implements a Business Strategy 6 l.B.3. Many Parts from Many Suppliers Must Work Together 8 l.B.4. Some Examples of Poor Assembly Design 9 1.C. Assembly in the Context of Product Development 9 l.D. Assembling a Product 11 1.E. History and Present Status of Assembly 12 I.E.I. History 12 1.E.2. Manual and Automatic Assembly 13 1.E.3. Robotic Assembly 14 l.E.4. Robotics as a Driver 15 l.E.5. Current Status and Challenges in Assembly 16 1.F. Assemblies Are Systems 16 1.G. Chapter Summary 17 l.H. Problems and Thought Questions 17 1.I. Further Reading 18 2 ASSEMBLY REQUIREMENTS AND KEY CHARACTERISTICS PREFACE xix 1 WHAT IS ASSEMBLY AND WHY IS IT IMPORTANT? 2.A. Prolog 19 2.B. Product Requirements and Top-Down Design 19 2.C. The Chain of Delivery of Quality 20 2.D. Key Characteristics 21 2.E. Variation Risk Management 22 2.E. 1. Key Characteristics Flowdown 23 2.E.2. Ideal KC Process 25 V VI CONTENTS 3.A. Introduction 34 3.B. Types of Assemblies 34 3.B.1. Distributive Systems 34 3.B.2. Mechanisms and Structures 35 3.B.3. Types of Assembly Models 36 3.C. Matrix Transformations 36 3.C.I. Motivation and Example 36 3.C.2. Nominal Location Transforms 37 3.C.3. Variation Transforms 42 3.D. Assembly Features and Feature-Based Design 42 3.D.1. History 43 3.D.2. Fabrication Features 43 3.D.3. Assembly Features 44 3.D.4. The Disappearing Fabrication Feature 44 3.E. Mathematical Models of Assemblies 45 3.E.1. World Coordinate Models 45 3.E.2. Surface-Constrained Models 46 3.E.3. Connective Models 46 3.E.4. Building a Connective Model of an Assembly by Placing Feature Frames on Parts and Joining Parts Using Features 47 3.E.5. A Simple Data Model for Assemblies 51 3.F. Example Assembly Models 53 3.F.1. Seeker Head 53 3.F.2. Juicer 55 3.G. Chapter Summary 57 3.H. Problems and Thought Questions 57 3.I. Further Reading 60 4 CONSTRAINT IN ASSEMBLY 4.A. Introduction 62 4.B. The Stapler 63 4.C. Kinematic Design 63 4.C.1. Principles of Statics 63 4.C.2. Degrees of Freedom 65 2.F. Examples 26 2.F.1. Optical Disk Drive 26 2.F.2. Car Doors 27 2.G. Key Characteristics Conflict 29 2.H. Chapter Summary 31 2.I. Problems and Thought Questions 32 2.J. Further Reading 32 3 MATHEMATICAL AND FEATURE MODELS OF ASSEMBLIES [...]... Fixture 411 15 .F.9 Auxiliary Operations 411 15 .F .10 Assembly Choreography 411 15 .F .11 Assembly Time Estimation 413 15 .F .12 Assembly Time Comparison 413 15 .F .13 Assembly Efficiency Analysis 413 15 .F .14 Design Improvements for the Staple Gun Design for Assembly 413 15 .F .15 Lower-Cost Staple Gun 414 15 .G DFx's Place in Product Design 415 15 .H Chapter Summary 416 15 .I Problems and Thought Questions 417 15 .J... Contact 286 10 .J.4 Insertion Forces 287 10 .J.5 Computer Program 288 11 ASSEMBLY OF COMPLIANT PARTS 11 .A Introduction 293 11 .A .1 Motivation 293 11 .A.2 Example: Electrical Connectors 295 11 .B Design Criteria and Considerations 296 11 .B .1 Design Considerations 296 11 .B.2 Assumptions 297 11 .B.3 General Force Considerations 297 11 .C Rigid Peg/Compliant Hole Case 299 11 .C .1 General Force Analysis 299 11 .D Design... 11 .D Design of Chamfers 304 11 .D .1 Introduction 304 xi XII CONTENTS 11 .D.2 Basic Model for Insertion Force 304 11 .D.3 Solutions to Chamfer Design Problems 306 11 .E Correlation of Experimental and Theoretical Results 311 11 .F Chapter Summary 312 11 .G Problems and Thought Questions 313 11 .H Further Reading 314 11 .I Appendix: Derivation of Some Insertion Force Patterns 314 11 .I .1 Radius Nose Rigid Peg, Radius... All Feasible Sequences 19 0 7.D .1 First Question: R(l;2,3,4) 19 1 7.D.2 Second Question: R(2 ;1, 3,4) 19 1 7.D.3 Third Question: R(3 ;1, 2,4) 19 1 7.D.4 Fourth Question: R(4 ;1, 2,3) 19 1 7.D.5 Reconciliation of the Answers 19 2 7.D.6 Precedence Question Results 19 2 7.E The Cutset Method 19 2 7.F Checking the Stability of Subassemblies 19 3 7.G Software for Deriving Assembly Sequences 19 4 7.G .1 Draper Laboratory/MIT... Analysis 476 17 .H Design Methods 477 17 .H .1 Simulation Software and Other Computer Aids 477 17 .H.2 Algorithmic Approach 478 17 .I Examples 4 81 17.I .1 Sony Phenix 10 Assembly Station 4 81 17.I.2 Window Fan 483 17 .I.3 Staple Gun 483 17 .I.4 Making Stacks 484 17 .I.5 Igniter 484 17 .J Chapter Summary 488 17 .K Problems and Thought Questions 488 17 .L Further Reading 488 18 ECONOMIC ANALYSIS OF ASSEMBLY SYSTEMS 18 .A... 314 11 .I.2 Straight Taper Rigid Peg, Cantilever Spring Hole 315 11 .J Appendix: Derivation of Minimum Insertion Work Chamfer Shape 316 12 ASSEMBLY IN THE LARGE: THE IMPACT OF ASSEMBLY ON PRODUCT DEVELOPMENT 12 .A Introduction 317 12 .B Concurrent Engineering 317 12 .C Product Design and Development Decisions Related to Assembly 319 12 .C .1 Concept Generation 320 12 .C.2 Architecture and KC Flowdown 320 12 .C.3... Technique 454 16 .L .1 Theory and Limitations 454 16 .L.2 Software 454 16 .L.3 Example 455 16 .L.4 Extensions 457 16 .M Example Lines from Industry: Sony 458 16 .N Example Lines from Industry: Denso 458 16 .N .1 Denso Panel Meter Machine ( ~19 75) 458 XV XVI CONTENTS 16 .N.2 16 .N.3 16 .N.4 16 .N.5 Denso Alternator Line ( ~19 86) 458 Denso Variable Capacity Line ( ~19 96) 459 Denso Roving Robot Line for Starters ( ~19 98) 460... and Interchangeability 11 3 5.B.2 Recent History of Parts Accuracy and Dimensioning and Tolerancing Practices 11 4 5.B.3 Remarks 11 6 5.C KCs and Tolerance Flowdown from Assemblies to Parts: An Example 11 6 5.D Geometric Dimensioning and Tolerancing 11 8 5.D.I Dimensions on Drawings 11 8 5.D.2 Geometric Dimensioning and Tolerancing 11 8 5.E Statistical and Worst-Case Tolerancing 12 3 5.E .1 Repeatable and Random... Different? 10 1 4.G Advanced Constraint Analysis Technique 10 2 4.H Comment 10 2 4.I Chapter Summary 10 2 4.J Problems and Thought Questions 10 3 4.K Further Reading 10 6 4.L Appendix: Feature Toolkit 10 7 4.L .1 Nomenclature for the Toolkit Features 10 7 4.L.2 Toolkit Features 10 7 5 DIMENSIONING AND TOLERANCING PARTS AND ASSEMBLIES 5.A Introduction 11 2 5.B History of Dimensional Accuracy in Manufacturing 11 3 5.B.I... 436 16 .G.3 Effect of Assembly Faults on Assembly Cost and Assembly System Capacity 436 16 .H Buffers 440 16 .H .1 Motivation 440 16 .H.2 Theory 4 41 16.H.3 Heuristic Buffer Design Technique 442 16 .H.4 Reality Check 442 16 .I The Toyota Production System 443 16 .I .1 From Taylor to Ford to Ohno 443 16 .I.2 Elements of the System 443 16 .I.3 Layout of Toyota Georgetown Plant 445 16 .I.4 Volvo's 21- Day Car 445 16 .J . PARTS CONTENTS xi 11 .A. Introduction 293 11 .A .1. Motivation 293 11 .A.2. Example: Electrical Connectors 295 11 .B. Design Criteria and Considerations 296 11 .B .1. Design Considerations 296 11 .B.2 Lead-ins 409 15 .F.7. Fixture and Mating Features to Fixture 409 15 .F.8. Assembly Aids in Fixture 411 15 .F.9. Auxiliary Operations 411 15 .F .10 . Assembly Choreography 411 15 .F .11 . Assembly. 311 11 .F. Chapter Summary 312 11 .G. Problems and Thought Questions 313 11 .H. Further Reading 314 11 .I. Appendix: Derivation of Some Insertion Force Patterns 314 11 .I .1. Radius Nose Rigid