A Framework for Modular Product Design based on Design for ‘X’ Methodology A thesis submitted to the Graduate School of the University of Cincinnati in partial fulfillment of the requirements for the degree of Master of Science in the School of Dynamic Systems of the College of Engineering and Applied Science 2013 by Anoop Sreekumar Bachelor of Technology (B.Tech.) Amrita Viswa Vidyapeetham, Kerala, India, May 2010 Committee Chair: Dr. Anil Mital ABSTRACT New products are routinely introduced in the expanding consumer market. In spite of incorporating many advanced technical features, only a few of these are financially successful. While competition, economic, and cultural, experience, and reputation factors are major influences in the success, or failure, of a product, a well-researched and efficient design distinguishes successful products from others. Product design and development, is a vastly researched topic and Design for ‘X’ (DFX) methodology is the basis for majority of product design procedures presently. Yet, there exist no framework for product design and development that can guide a designer through each design criterion, or ‘X’, in this methodology. Such a framework, if existed, would list out the design attributes and design factors for each of the design criterion. This purpose of this work is to establish such a framework for designing products. It is intended for this framework to be interactive while guiding the designer through each factor that may be critical in design. The framework described here considers 8 different criteria, each broken into design factors and sub-factors. Each design criterion is discussed as a separate design module. The design factors in each module and their influences on product design have been discussed in separate sections. The inter-dependence of the design modules, design attributes, and design factors has been identified, establishing the need for a framework which can serve as the basis for a comprehensive database for all the ‘X’s’ in the DFX methodology. i ii ACKNOWLEDGMENTS Firstly, I would like to thank the University of Cincinnati for accepting me for my graduate degree and for the financial assistance provided during the course of my academic stay. I would like to express my sincere gratitude towards Dr. Anil Mital, my academic advisor, for his invaluable advice, assistance, and encouragement to me during the course of my graduate degree. He has always been available with his vast knowledge and experience, whenever I found obstacles in the advancement of my research. Without his guidance, I would not have been able to complete my work in a professional and timely manner. I would also like to thank Dr. David Thompson and Dr. Kumar Vemaganti for taking time out of their busy schedules to serve as members of my defense committee. I would also like to thank my colleague Vignesh Ravindran, who has been a source of great assistance to me with his suggestions during the course of this research. Last, but not the least, I would like to thank my family and all my friends for their unwavering support and faith in me. iii TABLE OF CONTENTS Abstract…………………………………………………………………………………………….i Acknowledgment…………………………………………………………………….……………iii Table of Contents…………………………………………………………………………………iv List of Figures…………………………………………………………………….….....................ix List of Tables………………………………………………….…………………….………….…xi 1. Introduction……...………………………………………………………………..……….1 1.1 New Product Design and Development……………………………………...……1 1.2 Importance of Product Design and Development…………………………………1 1.3 Design for ‘X’ and its incorporation…………………………………………….…3 1.4 Framework Description..………………………………………………………..…3 2. Literature Review………………………………………………………..…………...……5 2.1 Products: Classifications and Examples…………………………………..….……5 2.2 Stages of New Product Design and Development………………………...………7 2.3 Modularity in Product Design……………………………………………..………9 iv 2.4 Design for Manufacturing (DFM) and Design for X (DFX)….…………………..9 2.4.1 Design for Functionality.............................................................................12 2.4.2 Design for Materials………………………………………....…………....13 2.4.3 Design for Assembly and Disassembly……………....…….….……….…14 2.4.4 Design for Maintenance…………………...……………………………...15 2.4.5 Design for Usability………………………………………………………16 2.4.6 Design for Reliability………………..….…..……………….…...…….…17 2.4.7 Design for Cost…………………………………………………………...17 2.4.8 Design for Environment…………………………………………………..18 2.4.9 Design for Quality……………………………………………....…….…..19 2.5 Limitations of the current research………………………………………….…….20 3. Objective and Methodology………………………...………………………….………...21 3.1 Objective of the research..........…………………………………………………...21 3.2 The Product Design Flower Diagram……………………………………………..21 3.3 Methodology: Design factor identification, classification and inter-dependence...23 v 3.3.1 Methodology………………………………...…………...…………...…..23 3.3.2 Inter-module interdependence……………………………………………24 3.4 Relevancy of the research ………………………………………………………..24 4. Modules of the Framework…………………………………………...……...……...……26 4.1 Function-Information Module……………………………………………………26 4.2 Materials Module……………………………………………………...………….29 4.3 Assembly - Disassembly Module…………………………………………………31 4.3.1 Grasping Attribute…………………………………………………..……33 4.3.2 Motion Attribute……………………………………………………….…35 4.3.3 Orientation Attribute.............. ……………………………………………35 4.3.4 Connection Attribute……………………………………………………..36 4.4 Maintenance Module……………………………………………………………..37 4.5 Usability Module……………………………………………………………....…41 4.5.1 User Aggregation Level…………………………………………..………43 4.5.2 Functionality Aggregation Level…………………………………………43 vi 4.5.3 Reliability Aggregation Level……………………………….…………....43 4.5.4 Maintainability Aggregation Level…………………………….…………43 4.5.5 Safety Aggregation Level…………………………...……………………44 4.6 Reliability Module………………………………………………………………..45 4.6.1 Mechanical Aggregation Level…………………………………………...46 4.6.2 Human Aggregation Level………………………………………………..47 4.6.3 Environmental Aggregation Level………………………………………..47 4.6.4 Maintainability Aggregation Level……………………………………….48 4.6.5 Contributory Aggregation Level………………………………………….48 4.7 Cost and Environment Module…………………………………………………...49 4.7.1 Design for Cost/Economy (Cost/Economy Module)...…………………...49 4.7.2 Assembly Costs…………………………………………………………..50 4.7.3 Disassembly Costs………………………………………………………..50 4.7.4 Maintenance Costs………………………………………………………..51 4.7.5 Form Cost Aggregation Level……………………………………………51 vii 4.7.6 Material Cost and Process Costs…………………………………….……51 4.7.7 Design for Environment: Environment Module……..……….…...…...…52 4.8 Design for Quality (Quality Module)..…………………………………………...56 4.8.1 Functionality Requirements for Quality………………………………….56 4.8.2 Usability Requirements for Quality………………………………………57 4.8.3 Reliability Requirements for Quality……………………………………..57 4.8.4 Maintainability Requirements for Quality………………………………..57 4.8.5 Material Requirements for Quality……………………………………….57 5. Conclusion…………...……………….…..………………………………………..…......58 6. Future Work...…………………………...………………………………………………..61 6.1 Development of an interactive designer aid system………………………………61 6.2 Role of framework in the interactive system……………………………………...61 6.3 Capturing functional knowledge: deriving information from the framework…....61 6.4 Interaction between modules in the system………………………...…………….69 6.5 Final Remarks………………………………………………………………….....70 7. References………………………………………………………………………...............72 viii LIST OF FIGURES Figure 2.1 Product Categories and Examples…………………………………………6 Figure 3.1 The Product Design Flower Diagram…………………………………….22 Figure 3.2 Methodology for establishment of the framework and the interaction between criteria, modules and design factors…………………………….25 Figure 4.1 Design factor breakdown of grasping attributes………………………….34 Figure 4.2 Design factors breakdown for the maintenance module…………………39 Figure 4.3 Aggregation levels and design factor classification in the Usability Module……………………………………………………………………42 Figure 4.4 Aggregation levels and design factors in the Reliability Module………..46 Figure 4.5 Aggregation levels and design factor breakdown for the Cost/Economy Module…………………………………………………………….……...50 Figure 4.6 Environmental concerns in design for environment……………………...54 Figure 5.1 (A) Product Design Framework with aggregation levels……………………..59 Figure 5.1 (B) Progression of the framework: Modules, Aggregation Levels, Design Factors, Design Parameters and Interactive Questionnaire………………60 Figure 6.1 Captured functional knowledge of a standard component………......…..62 ix Figure 6.2 Sample product: Disassembly of a ball point pen…….………………...63 Figure 6.3 Extraction of shape attributes for the custom component………...……65 Figure 6.4 Extraction of performance attributes for the custom component.….…..66 Figure 6.5 Extraction of force-motion attributes for the custom component….…..67 Figure 6.6 Captured functional knowledge of standard and custom components....68 Figure 6.7 Menu driven questionnaire in the intreactive system……………….….69 x LIST OF TABLES Table 2.1 Functions specific to three stages of product design and development……..7 Table 4.1 Design attributes and design factors in the Function-Information Module...28 Table 4.2 Design Factors affecting Material Selection………………………………..29 Table 4.3 Determinants in assembly/disassembly……………………………………..32 Table 4.4 Attributes and design factors in assembly/disassembly…………………….33 Table 4.5 Tool Factors………………………………………………………………...34 Table 4.6 Human Factors……………………………………………………………...34 Table