Design and Analysis of Integrated Manufacturing Systems (1988) / Chapter Skim
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The Strategic Approach to Product Design
The Strategic Approach to Product Design
Pages 200-224
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From page 200... ...
is a multistep process that seeks to implement integrated product and process design. Because of the inherently integrative nature of the assembly process, that is Me focus of SAPD.
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From page 201... ...
An approach that integrates product design and all aspects of the manufacturing process can only be accomplished through a strategic approach to product design (SAPD)
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From page 202... ...
Design for fabrication, sometimes mistakenly called design for manufacturability, considers parts as isolated entities rather than in groups that must function together. SAPD seeks to correct that shortcoming.
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Products and systems are being de203 signed more rapidly, in part through better planning and more effective computer tools. Better planning means organizing the design process so that more factors are taken into account early, reducing the chance of damaging surprises later.
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New production technology requires new skills and attitudes from workers and managers. Product and process complexity arise from the appearance of new kinds of products, many of which contain a true mix or integration of mechanical and electronic functions, thus requiring more broadly educated product and process designers.
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Since the product design must recognize strategic issues related to both the manufacturer and the user of the product, the required response has been called the strategic approach to product design. The remainder of this paper focuses on SAPD as a process and as a discipline.
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Market Needs Production Syatern Tedilobgy | Product | | Performance | 1 SPEW 1 1 ~~:~ 1 ,.. ~ 1 Investment Decision MetilOdS Product Design Production Hem I Prodllction L Cost Model FUGUE 2 The emerging concurrency method of designing products and production systems.
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From page 207... ...
· A product function analysis is made to determine if the product's producibility and usability can be improved without impairing desirable functions. · An assembly process is designed that includes a suitable assembly sequence, the identification of subassemblies, the integration of a quality control strategy with assembly, and the design of each part so that its functional tolerances and tooling toler
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From page 208... ...
Given the present state of design methodology and techniques, the best way to pursue these activities is to form teams of product designers and manufacturing engineers, with active participation by representatives from marketing, finance, purchasing, and personnel. Some companies call this process top-down analysis; others call it concurrency.
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From page 209... ...
· Anticipate fabrication and assembly methods and problems. · Simplify the design, fabrication, use, and repair by, for example, reducing the number of parts or identifying and increasing the number of parts common to different models.
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From page 210... ...
Activities with strategic implications include blies; · Division of the product into subassem· Establishment of an assembly sequence; · Selection of an assembly method for each step; and · Integration of a quality-control strategy. There is no set order in which to consider these activities, since the choices interact, and making them may trigger more design changes.
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From page 212... ...
Thus, the choice of sequence, normally considered late in the process design, really belongs in the early stages, since each can heavily affect the other. For these reasons, "determination of alternate assembly sequences" occupies the center of Figure 3.
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A rational approach involves examining the assembly sequence to determine where each fault becomes critical and each test opportunity occurs. This study may result in a new assembly sequence.
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· Low line efficiency resulted from ineffective job classifications and a centrally controlled maintenance group. Low line efficiency created an excessive inventory and a low utilization of equipment.
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To meet this challenge, Nippondenso has employed several strategies, including in-house development of manufacturing technology, jigless manufacturing methods (where possible) , and the combinatorial method of meeting model mix.
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tQ Assembly sequence group. u' pares ~ Subassembly Identincatlon and sub- Tolerancing for assembly sequence assembiles ac strategy Tooling design and accuracy control Detailed simulation Ute-cycle cost models FIGURE 6 Activities and knowledge needed to support the strategic approach to product design: Part 1- Product design.
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From page 217... ...
For example, there is a need for augmented CAD descriptions of the parts, including notations of possible assembly sequences and call-out of the relevant tolerances on jigging and gripping surfaces. There is a need for cost-tolerance data, so that the impact of various processing and assembly strategies can be assessed, and for part-mating data linked to the tolerances, so that overall assembly errors and likelihood of assembly success can be calculated.
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From page 218... ...
Specific Near-Term Knowledge Progress is being made in the following specific topical areas: · Methods of generating alternate assembly sequences for products. · Algorithms for assessing the tolerances assigned to parts to see if they support a particular assembly sequence.
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From page 219... ...
By contrast, the usual practice has been to delay consideration of the assembly sequence until after the parts are designed and fabrication methods have been chosen. 219 Since different fabrication methods cost different amounts and are capable of making parts to different tolerances, these choices, if made without assembly process knowledge, can render an assembly sequence unrealizable.
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From page 220... ...
· System syntheses: Algorithms are avail able that can design assembly or fabrication systems (CSDL Reports 1978-1980, R-1284, R-1406, Graves and Lamar, 1983; Holmes, 1987~. That is, given the assembly sequence and data on alternative equipment or peo ple capable of performing each of the as sembly steps, the algorithm will select peo , ple or equipment and assign the steps to the evaluation process.
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From page 221... ...
The assembly sequence itself is an excellent focus for the interaction between product and manufacturing engineers. The assembly sequence can act as the framework for discussions of tolerances, testing strategies, assembly methods, and various economic analyses.
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From page 222... ...
1987. Simplified generation of all assembly sequences.
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From page 223... ...
Shipyards. CSDL report prepared for Todd Pacific Shipyard, Los Angeles Division, and SNAME Ship Production Committee Panel SP-10, Flexible Automation.
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