QCAD A Framework for Total Quality Development in an Object Oriented Knowledge Based Engineering Environment by Yale Goldis B.S., Mechanical Engineering Tufts University, 1991 Submitted to the Department of Mechanical Engineering in Partial Fulfillment of the Requirements for the Degree of Master of Science in Mechanical Engineering at the Massachusetts Institute of Technology February 1994 © 1994 Massachusetts Institute of Technology All rights reserved Signature of Author............................ ............................................................................ Department of Mechanical Engineering January 14, 1994 Certified by ..................................... .... ,..... ............ Don P. Cl sing Bernard M. Gordon Adjunct Professor of .... , gin4ering Innovation and Practice Thesis Advisor Accepted by ...................................................................................................................... Ain Sonin Chairman Departmental Graduate Committee Department of Mechanical Engineering MASSACHUSETTSINSTI'TUTE OFTF"'lt'll nly MAR 08 1994 UBRARIE$ QCAD A Framework for Total Quality Development in an Object Oriented Knowledge Based Engineering Environment by Yale Goldis Submitted to the Department of Mechanical Engineering on January 14, 1994 in partial fulfillment of the requirements for the Degreee of Master of Science in Mechanical Engineering Abstract Conventional knowledge based engineering (KBE) systems connect engineers to engineers. These design systems integrate corporate engineering practices into a computerized framework. The intention is to quickly and efficiently create a product specification, leaving engineers time for other design tasks. KBE applications address conceptual design, geometric design, and part manufacturability, but do so in a segmented fashion. This segmentation is reminiscent of the throw it over the wall approach to design. Each program optimizes its own task at the expense of the overall system. Many companies today use multifunctional product development teams and total quality development methods to break down barriers among departments. KBE design systems should follow suit. To expand the horizons of computerized knowledge based engineering, this thesis develops the Quality Computer Aided Design (QCAD) system and tests it with both an easy to understand clamp model and a more complex copier model. The QCAD rrthodology consists of two parts: (1) a design process framework and (2) a computer program for use with the design framework. It is intended that a multifunctional product development team use QCAD to assist in developing both new and variational products from function designation to hardware definition to process specification. The QCAD system was implemented in the ICAD design language (IDL). ICAD is the leading supplier of commercial knowledge based engineering software worldwide. IDL is a super set of common lisp, an object oriented programming language, and is geared toward modeling products in the ICAD user interface. Comments are expressed about the benefits and drawbacks of combining the two design methods in a product development environment. Future improvements and research work are also suggested. Thesis Advisor: Don P. Clausing Title: Bernard M. Gordon Adjunct Professor of Engineering Innovation and Practice 2 Acknowledgments First, I would like to thank my advisor, Professor Don Clausing, for his support, guidance, and assistance on this thesis. I appreciate the direction and freedom he gave me to explore this topic. I am most grateful to him for teaching me about total quality development and for giving me the opportunity to study cultural change with him. I am truly fortunate to have him as an advisor. Second, I would like to thank Professor Ron Andrade, who is here on sabbatical, but gave his assistance with my thesis anyway. Moreover, I appreciate our countless philosophical discussions about life, the universe, and everything. Third I would like to thank Diane de Alderete for her indispensable administrative support. Fourth, I would like to thank all of the people at ICAD for their assistance with this project, including: Larry Rosenfeld for his support; Tom Smith, June Powers, and Phil Stockton for the training sessions; Mark Ouelette, Bill Brand, and Ralph Verrilli for their interviews; Mark Ouelette and Bob Phillips for the innumerable conversations and programming support. Furthermore, I would like to thank the people at MIT for their assistance with this project, including: Professor George Chryssolorus and the students in his lab for the use of their workstation; Kevin Spratt for his assistance in configuring that workstation; and Afiita Flynn in the artificial intelligence lab for her assistance with the initial installation of ICAD. Lastly, I would like to thank my parents and friends for their patience and understanding. I would also like to thank the Leaders for Manufacturing Program for its support of this work. 3 Table of Contents 1. Introduction .............................................................................................................. 7 2. Review of Total Quality Development ........................................... 12 2.1. Overview ........................................... 12 2.2. Design Process Structure........................................... 13 2.3. Basic Quality Function Deployment ........................................... 15 2.4. Pugh Concept Selection ........................................... 20 2.5. Enhanced Quality Function Deployment .............................................. 22 2.6. Taguchi System of Quality Engineering ........................................... 24 3. Review of Computers in Design ................................................................ ...............31 3.1. Overview ........................................... 31 3.2. Introduction to Knowledge Based Engineering .......................................... 32 3.3. Conventional Design Assistants ........................................ .......................... 34 3.3.1. Technically Focused Assistants ...................................................... 35 3.3.2. Quality Focused Assistants ............................................................ 36 3.4. Design History System s .............................................................................. 37 3.4.1. Design Representation Formats ........................................... 37 3.5. Knowledge Based Design Systems ........................................... 38 3.5.1. CAD Systems ........................................... 39 3.5.2. ICAD ........................................... 40 3.5.2.1. Representative ICAD Projects ......................................... 41 3.5.3. Quality Design Systems ........................................... 42 3.6. Summary ........................................... 44 4. QCAD Definition . ........................................... .47 4.1. Overview ........................................... 47 4.2. Initial Development ................................................................................... 48 4.3. Basic QCAD Framework ........................................................................... 55 4.4. Design Process in QCAD .......................................................................... 59 4.4.1. Function Hierarchy ........................................................................ 62 4.4.2. Hardware Hierarchy ....................................................................... 66 4.4.3. Process Hierarchy .......................................................................... 69 4.5. Computerized Elements of QCAD............................ .................... 71 4.5.1. Description of Clamp Product M odel ........................................... 72 4.5.2. Function Hierarchy ........................................................................ 74 4.5.2.1. Function Identification................................. 74 4.5.2.2. Constraints ................................................... ..............75 4.5.2.3. QFD House of Quality M atrix ........................................ 76 4.5.2.4. Function Diagram............................................................ 79 4.5.2.5. Concept Generation ................................. 81 4.5.2.6. Concept Selection ........................................................... 82 4 4.5.2.7. Concept Review .............................................................. 84 4.5.2.8. Additional Comments ...................................................... 85 4.5.3. Hardware Hierarchy ........................................................... 85 4.5.3.1. Product Structure Diagram . ................................ 86 4.5.3.2. QFD Design Matrix ......................................................... 87 4.5.3.3. Hardware Parameters ...................................................... 88 4.5.3.4. Product Parameter Design ............................................ 89 4.5.3.5. Material and Process Selection ........................................ 90 4.5.3.6. Concept Review .............................................................. 91 4.5.3.7. Additional Comments ...................................................... 92 4.5.4. Process Hierarchy .......................................................................... 93 4.5.4.1. Bill of Materials............................................................... 93 4.5.4.2. Process Parameters . ...... 94 4.5.4.3. Process Parameter Design ..............................................