1、 ABSTRACTIn the last few years, corporation has engaged in studies to improve their design processes, ranging from marketing to support. Recent government, academic and industrial sector initiatives have sought advance technologies for developing and managing product development environment. Many co
2、mpanies have established a concurrent design process for their product development and have recognized a need for tools in evaluating the level of decomposition and integration, while analyzing the impact on the final design. This article will propose a three-phase methodology for design of products
3、 while considering modularity, assembly and manufacture.KEYWORDSModularity, Group technology, Optimization, Decomposition, Classification1. IntroductionModular design is a design technique that can be used to develop complex products using similar components . Components used in a modular product mu
4、st have features that enable them to be coupled together to form a complex product. Modular design can be also viewed as the process of producing units that perform discrete functions, and then the units are connected together to provide a variety of functions. Modular design emphasizes the minimiza
5、tion of interactions between components, which will enable components to be designed and produced independently from each other. Each component, designed for modularity, is supposed to support one or more function. When components are structured together, to form a product, they will support a large
6、r or general function. This shows the importance of analyzing the product function and decomposing it into sub-functions that can be satisfied by different functional modules. Modularity can be applied in the product design, design problems, production systems, or all three. It is preferable to use
7、the modular design in all three types at the same time.Modular products refer to products that fulfill various overall functions through the combination of distinct building blocks or modules. In the sense that the overall function, performed by the product, can be divided into sub functions that ca
8、n be implemented by different modules or components. An important aspect of modular products is the creation of a basic core unit to which different elements (modules) can be fitted, thus enabling a variety of versions of the same module to be produced. The core should have sufficient capacity to co
9、pe with all expected variations in performance and usage.Most design problems can be broken down into a set of easy to manage simpler sub-problems. Sometimes complex problems are reduced into easier sub-problems, where a small change in the solution of one sub-problem can lead to a change in other s
10、ub-problems solutions. This means that the decomposition has resulted in functionally dependent sub-problems. Modularity focuses on decomposing the overall problem into functionally independent sub-problems, in which interaction or interdependence between sub-problems is minimized. Thus, a change in
11、 the solution of one problem may lead to a minor modification in other problems, or it may have no effect on other sub-problems.Modularity in production systems aims at building production systems from standardized modular machines. The fact that a wide diversity of production requirements exists ha
12、s led to the introduction of a variety of production machinery, and a lack of agreement on what the building blocks should be. This means that there are no standards for modular machinery. In order to build a modular production system, production machinery must be classified into functional groups f
13、rom which a selection of a modular production system can be made to respond to different production requirements. Rogers classified production machinery into four basic groups of “primitive” production elements. These are process machine primitives, motion units, modular fixtures, and configurable c
14、ontrol units. It is argued that if a selection is made from these four categories, it will be possible to build a diverse range of efficient, automated and integrated production system.2Overview of Product DevelopmentProduct development is a necessary and important part of the activities performed b
15、y a manufacturing firm. Due to changes in manufacturing technology, consumer preferences, and government regulations (to name a few influences), existing products will become less profitable over time. The sales volume of a typical product starts slowly, accelerates, becomes flat, and then steadily
16、declines. Although there may be a few products that remain profitable for many years, firms continually develop new products that will generate more profits. Product development determines what the firm will manufacture and sell. That is, it attempts to design products that customers will buy and to
17、 design manufacturing processes that meet customer demand profitably. Poor decisions during product development lead to products that no one wants to buy and products that are expensive to manufacture in sufficient quantity.A product development process is the set of activities needed to bring a new
18、 product to market. A product development organization includes the engineers, managers, and other personnel who make process and product engineering decisions and perform these activities. (Note that, in this paper, the term new product covers the redesign of an existing product as well.)Because ma
19、king good decisions requires expertise and an organization of people can be experts in only a few things, a manufacturing firm specializes in a certain class of products. It focuses its attention on the market for that class of products, the technologies available to produce that class, and the regu
20、lations relevant to that class.Like other parts of the business, a product development organization seeks to maximize the profit of the manufacturing firm subject to the relevant regulatory and ethical constraints and other conditions that the firms owners impose based on their values. A product dev
21、elopment organization does this by regularly introducing new products that the firm can manufacture, market, and sell. Fundamentally, then, a product development organization transforms information about the world (e.g., technology, preferences, and regulations) into information about products and p
22、rocesses that will generate profits for the firm. It performs this transformation through decision-making (Herrmann and Schmidt, 2002). Because the design problem is highly complex, product development teams decompose the problem into a product development process, which provides the mechanisms for
23、linking a series of design decisions that do not explicitly consider profit.The following nine steps are the primary activities that many product development processes accomplish (Schmidt et al., 2002):Step 1. Identify the customer needs.Step 2. Establish the product specification.Step 3. Define alt
24、ernative concepts for a design that meets the specification.Step 4. Select the most suitable concept.Step 5. Design the subsystems and integrate them.Step 6. Build and test a prototype; modify the design as required.Step 7. Design and build the tooling for production.Step 8. Produce and distribute t
25、he product.Step 9. Track the product during its life cycle to determine its strengths and weaknesses.This list (or any other description that uses a different number of steps) is an extremely simple depiction that not only conveys the scope of the process but also highlights the inherent (but unques
26、tioned) decomposition. There are many other ways to represent product development processes and the component tasks, including the use of schedules or a design structure matrix (Smith and Eppinger, 2001).Manufacturing firms understand that design decisions (though made early in the product life cycl
27、e) have an excessive impact on the profitability of a product over its entire life cycle. Consequently, product development organizations have created and used concurrent engineering practices for many years (Smith, 1997, provides a historical view). Many types of tools and methods (such as cross-fu
28、nctional product development teams and design for manufacturing guidelines) have been created, adopted, and implemented to improve decision-making. Cooper (1994) identifies three generations of formal approaches to product development, all of which involve decomposition.It should be noted, however,
29、that decomposition is not the only way to describe product development. As an alternative to decomposing a system design problem into subproblems, Hazelrigg (1996) proposes creating and refining system design models to express how detailed design variables affect the overall system performance. This
30、 approach suggests that a product development process would end with using the model to find the optimal design. Hazelrigg (1998) encourages this type of optimization but does not discuss the process of generating the profit maximization model.3. A Methodology for Design for ModularityA three-phase
31、methodology is proposed for the development of complex products using the modularity concept 1,2. The proposed methodology matches the criteria set by the design for functionality, assembly and manufacture. Some of the major benefits associated with this methodology include: Increased design accurac
32、y, efficiency, and the reuse of existing design for new programs. Potential for integration of the developed methodology and technology into the engineering design activities. Modular product design and the process of planning the production are integrated in one overall engineering process in which product features are mapped into their feasible process(es) in a one to one correspondence.In order to implement this concept successfully, the manner in which the modules are selected is critical. By establishing simple in
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