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design for manufacturing and assembly

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  1. 1. DFMA – Design for manufacturing and assembly
  2. 2. Purpose Statement To provide an overview of Design for Manufacturing and Assembly (DFMA) techniques, which are used to minimize product cost through design and process improvements.
  3. 3. Design for Manufacturing Definition: DFM is the method of design for ease of manufacturing of the collection of parts that will form the product after assembly. ‘Optimization of the manufacturing process…’ DFA is a tool used to select the most cost effective material and process to be used in the production in the early stages of product design.
  4. 4. Major DFM objectives 1) Estimate the mfg. costs 2) Reduce the costs of components 3) Reduce the costs of assembly 4) Reduce the costs of supporting production 5) Consider the impact of DFM decisions on other factors.
  5. 5. Design for Assembly Definition: DFA is the method of design of the product for ease of assembly. ‘…Optimization of the part/system assembly’ DFA is a tool used to assist the design teams in the design of products that will transition to productions at a minimum cost, focusing on the number of parts, handling and ease of assembly.
  6. 6. Differences Design for Assembly (DFA) • concerned only with reducing product assembly cost – minimizes number of assembly operations – individual parts tend to be more complex in design Design for Manufacturing (DFM) • concerned with reducing overall part production cost – minimizes complexity of manufacturing operations – uses common datum features and primary axes
  7. 7. Similarities • Both DFM and DFA seek to reduce material, overhead, and labor cost. • They both shorten the product development cycle time. • Both DFM and DFA seek to utilize standards to reduce cost
  8. 8. Terminology Design for Manufacturing (DFM) and Design for Assembly (DFA) are now commonly referred to as a single methodology, Design for Manufacturing and Assembly (DFMA) .
  9. 9. Sequence of Analysis Concept Design Design for Assembly Design for Manufacturing Detailed Design
  10. 10. Estimating Manufacturing Costs Estimate manufacturing Costs of Proposed Design Reduce costs of assembly Reduce costs of Supporting Production Reduce costs of components Consider DFM impact on other factors Recompute Manufacturing Costs Good Enough? Accepted Design N Y
  11. 11. DFMA – Design for manufacturing and assembly Design for Manufacturing (DFM) and design for assembly (DFA) are the integration of product design and process planning into one common activity. The goal is to design a product that is easily and economically manufactured.
  12. 12. The heart of any design for manufacturing system is a group of design principles or guidelines that are structured to help the designer reduce the cost and difficulty of manufacturing an item. The following is a listing of these rules
  13. 13. Reduce the total number of parts The reduction of the number of parts in a product is probably the best opportunity for reducing manufacturing costs. Less parts implies less purchases, inventory, handling, processing time, development time, equipment, engineering time, assembly difficulty, service inspection, testing
  14. 14. Develop a modular design The use of modules in product design simplifies manufacturing activities such as inspection, testing, assembly, purchasing, redesign, maintenance, service
  15. 15. Use of standard components Standard components are less expensive than custom-made items. The high availability of these components reduces product lead times.
  16. 16. Design parts to be multi-functional Multi-functional parts reduce the total number of parts in a design, thus, obtaining the benefits given in rule 1. Some examples are a part to act as both an electric conductor and as a structural member, or as a heat dissipating element and as a structural member.
  17. 17. Design parts for multi-use In a manufacturing firm, different products can share parts that have been designed for multi-use. These parts can have the same or different functions when used in different products. In order to do this, it is necessary to identify the parts that are suitable for multi-use. For example, all the parts used in the firm (purchased or made) can be sorted into two groups: the first containing all the parts that are used commonly in all products.
  18. 18. Design for ease of fabrication Select the optimum combination between the material and fabrication process to minimize the overall manufacturing cost. In general, final operations such as painting, polishing, finish machining, etc. should be avoided. Excessive tolerance, surface-finish requirement, and so on are commonly found problems that result in higher than necessary production cost.
  19. 19. Avoid separate fasteners The use of fasteners increases the cost of manufacturing a part due to the handling and feeding operations that have to be performed. Besides the high cost of the equipment required for them, these operations are not 100% successful, so they contribute to reducing the overall manufacturing efficiency. In general, fasteners should be avoided and replaced, for example, by using tabs or snap fits.
  20. 20. Fastener Cost • Select the most inexpensiv e fastening method required plastic bending riveting screwing snap fit
  21. 21. Minimize assembly directions All parts should be assembled from one direction. If possible, the best way to add parts is from above, in a vertical direction, parallel to the gravitational direction (downward). In this way, the effects of gravity help the assembly process, contrary to having to compensate for its effect when other directions are chosen.
  22. 22. Reference 1. Assembly Automation and Product Design G. Boothroyd, Marcell Dekker, Inc. 1992 2. Product Design for Manufacture and Assembly G. Boothroyd and P. Dewhurst, Boothroyd Dewhurst, Inc. 1989 Marcell Dekker, Inc. 1994 3. Design and Analysis of Manufacturing Systems Prof. Rajan Suri University of Wisconsin 1995 4. Product Design for Assembly: The Methodology Applied G. Lewis and H. Connelly