Design for X

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"Design for X" is a generic name for the members of a family of methodologies adopted for improve the project and conception of a product for a determined objective (as cost, assembly facility, repairing or other), of which Design for Manufacture is the oldest. [1] The need for such "Design for ..." methodologies was identified as engineers became increasingly aware of a lack of appropriate detailed knowledge in important product life-cycle processes. Design for X (DFX) methodologies can be seen also as tools to analyse designs for their suitability for identified aspects of a product’s life cycle. Of these, manufacturability and assemblability were among the first to have been considered, since both were highly apparent cost reduction drivers. [2]

Similarly, following the example of Design for Assembly (DFA) and Design for Manufacture (DFM), other DFX methodologies have been proposed which consider alternative life-cycle values, assessing parameters like quality, maintainability, reliability, safety regulations and environmental issues earlier in the design process.

DFX methodologies are tools to conceive and evaluate design of products and also processes, typically at both concept and detail levels. As such, to provide meaningful comparative data, they typically quantify aspects of the design such as cost, quality and regulatory conformity. [3] Thus they not only provide a benchmarking tool for designs but also provide an indication of the possible relative benefits of one design compared to another.

By the simple expedient of the number of hits registered on an internet search engine the researchers determined that the most prominent and widely used DFX methodologies are probably DFA and DFM. DFA provides methods to evaluate ease of assembly, assembly times and costs and also concerns the reduction of individual parts and the aggregation several components in assemblies that can be easierly mountend in the production line. DFM helps the designer to enhance manufacturability, and again provides manufacturing cost data for a product and its components. Complex cost models have similarly been developed for different manufacturing processes and their respective process parameters. [4] [5] [6]

Boothroyd (1994) has assessed DFA and DFM separately and explored possible trade-offs between assembly and manufacturing costs. Equipment set up times are considered in their work and are included in their cost models. These data are treated as constants in the calculations they undertake, where Boothroyd and Dewhurst fail to accurately determine differences in changeover times between various processes. In reality changeover times are strongly dependent on the product range and the manufacturing processes used. [7]

One objective of Design for Changeover (DFC) is to allow more accurate estimates of the changeover capabilities of manufacturing equipment, and the influence that features of the final design will have.

Design for Maintenance, also known as Design for Service (DFS), considers how subassemblies can be exchanged as quickly and easily as possible. Depending on the relative likelihood of failure of a specified component or subassembly, greater effort can be made to improve its maintainability. Primarily this is achieved by enhancing ease of assembly and disassembly of these specified elements, where the additional cost incurred to achieve this enhanced capability is justified.

Design for Disassembly is a more recent idea which aims to make the end of life processing of a product as simple as possible, to aid the reuse and recycling prospects of the components and materials.

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[edit] External links

[edit] References

  1. ^ Boothroyd, Geoffrey, Dewhurst, Peter. Knight, Winston (2002). Product Design for Manufacture and Assembly, Second Edition. Marcel Dekker. ISBN 0-8247-0584-X.
  2. ^ Benhabib, Beno (2003). Manufacturing: Design, Production, Automation, and Integration. Marcel Dekker,. ISBN 0-8247-4273-7.
  3. ^ Reik, M. P., Culley, S. J. Owen, G. W. Mileham, A. R. and McIntosh, R. I. (2004). Proc. 2nd Int. Conf. on Manufacturing Research: Advances in Manufacturing Technology: A novel product performance driven categorisation of DFX methodologies. Professional Engineering Publications (IMechE), 179–184.
  4. ^ Boothroyd, Geoffrey (1994). Product Design for Manufacture and Assembly, 1st edition, Marcel Dekker. ISBN 0-8247-9176-2.
  5. ^ Boothroyd, Geoffrey, Dewhurst, Peter. Knight, Winston (2002). Product Design for Manufacture and Assembly, 2nd Edition, Marcel Dekker. ISBN 0-8247-0584-X.
  6. ^ Swift, K. G., Booker, J. D. (1997). Process Selection: From Design to Manufacture. John Wiley. ISBN 0-470-23774-0.
  7. ^ McIntosh, R. I., Culley, S. J. Owen, G. W. Mileham, A. R. (2001). "Changeover improvement: a maintenance perspectiv" 73 (2): 153–163.
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