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Design for Assembly (DFA) - The Key to Making Parts-Count Reduction Profitable
Technical Paper
1999-01-2281
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
This paper explains, via specific examples, that no one-to-one correlation exists between design for assembly and parts-count reduction. It explains how overall cost reductions cannot be maximized if the cost of each and every step in a process is minimized separately, as it occurs. A distinction is drawn between goals and the metrics used to measure satisfaction of the goals, and concern is expressed at how frequently one now sees the metric usurping the function of the original goal - to the extent that satisfying the metric can result in directly violating what once was the goal. Illustrations are provided of how, and when, parts consolidation can be of overall benefit. Other examples reveal how parts-count reduction has been counterproductive. A better metric, interface control, is recommended as an alternative. The point is made that, when the superior choice of action is not self evident, the design-for-assembly (DFA) process will identify the best approaches, for both design and manufacturing, -provided that the DFA process is carried through to completion, and NOT merely to the limits of involvement for each individual department! The real goals are identified as minimization of total costs of manufacturing, acquisition, operation, and the like, better performance than competitive products, or of maximizing profits. Goals at this level, alone, can be universal, and not all can be satisfied simultaneously. The techniques of achieving these goals, of which parts-count reduction is only one, are never universal. They are sub-level goals and need to be recognized as such if they are not to do more harm than good.
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Authors
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Citation
Hart-Smith, L., "Design for Assembly (DFA) - The Key to Making Parts-Count Reduction Profitable," SAE Technical Paper 1999-01-2281, 1999, https://doi.org/10.4271/1999-01-2281.Also In
References
- Hart-Smith, L. J. “Interface Control - The Secret to Making DFMA ® Succeed” McDonnell Douglas Paper No. MDC 96K0132; presented at SAE Aerospace Manufacturing Technology Conference & Exposition, Seattle June 2-5”, 1997 published in Proceedings 1 10 SAE Paper No. 972191
- Hart-Smith, L. J. Internal Douglas Memo, circa 1972
- Hart-Smith, L. J. “Design and Development of the First Lear Fan All-Composite Aircraft” Douglas Paper 8184, presented as Keynote Address to Institution of Mechanical Engineers Conference on Advanced Composites London, England March 7-8 1989
- Hart-Smith, L. J. “On the Adverse Consequences of Cost-Performance Metrics Usurping the Role of Goals They Were Supposed to Support,” Boeing Paper MDC 97K0068, presented to 21st ICAS Congress Melbourne, Australia September 1998
- Duong, D. Madan, R. C. Konieczny, T. R. “Redesign of the C-17 Composite Tailcone McDonnell Douglas Paper MDC 95K0073, presented to 11th DODASA/FAA Conference on Fibrous Composites in Structural Design Fort Worth, Texas 26-29 August 1996 in Proceedings, WL-TR-97-3008 1 61 78
- Hart-Smith, L. J. “Innovative Concepts for the Design and Manufacture of Secondary Composite Aircraft Structures” McDonnell Douglas Paper MDC 93K0081, presented as Keynote Address to 5th Australian Aeronautical Conference Melbourne, Australia 13-15 September, 1993 in Proceedings 19 49
- Hart-Smith, L. J. “Designing with Advanced Fibrous Composites”, Douglas Paper 8011, presented as Keynote Address to Institution of Engineers, Australia, Bicentennial Conference on New Dimensions, MECH 88, Brisbane, Australia, May 9-10, 1988; in Proceedings Workshop on New Materials and Processes for Mechanical Design 1988, National Conference Publication No. 88/5, pp. 52-81; republished in Aeronautical Society of India 40 3 August 1988 167 199