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Products are artifacts conceived, produced and transacted, and used by people because of their properties and the functions they may perform. Product design is the process of devising and laying down the plans that are needed for the manufacturing, sustained use, and disposal of a product. Many factors have to be considered when designing a product. Consumers look upon the product as something to be bought and used. To the design engineer it is a technical-physical system that must function efficiently and reliably. An industrial designer considers the product to be an object that functions in a psychological sense and embodies cultural values. Manufacturing engineers have to produce it, often in large numbers, preferably fast, cheaply, accurately, and with the lowest possible number of faults. A marketer considers it a commodity with added value, something that people are prepared to buy. Entrepreneurs invest in new products and count on an attractive return. People that are not directly involved may see above all the reverse side of the coin: the undesirable and often even harmful side effects of production and use.
In every point of view there are requirements that must be taken into account. Product design therefore demands a multidisciplinary approach. With a multidisciplinary approach it follows that the product design is done with the support of many people working in one or many teams that may be centralized or decentralized or even spread around the world and in many different organizations. In such a development environment the capability to describe the emerging product or products and communicate effectively and efficiently around requirements, design solutions, trade-offs, and how to produce and make the product available to the customers becomes critically important.
Sohlenius (2005) proposes that the innovation process can be understood as combining a decision world with the human competence world and the modeling world (Figure 28). The design process is principally a decision process, where objectives are defined from the needs and expectations of the stakeholders. Stakeholders are primarily the customers, but are also the shareholders, the employees, and the society.
Sohlenius (2005) highlights the notion that the decision process involves two important orthogonal structures: the hierarchical product structure vertically and the causal structure horizontally (Figure 28). The hierarchical structure is a consequence of the inherent hierarchical nature of most products. A product is composed of (consists of) components that in turn may be composed of other components and so on. The causal structure is a consequence of objectives that are realized through means. The causal structure provides the connections between related positions in the hierarchical trees in adjacent domains.
Figure 28: Systemic map of innovation system and process (Sohlenius, 2005)
Gershenson et al. (2003) present an overview of existing research on the definition of modular product design and its benefits. A prediction of the future is also provided with a reference to Shah et al. (1996) that says that: "engineering design will increasingly make use of pre-designed and packaged modules". A framework for the definition of modularization and modular product systems was proposed by Pahl & Beitz (1996) that describes two different approaches to establish derivate products from a common design platform – size ranges and modularization. The aim of size ranges is the rationalization of product development by the implementation of the same function with the same solution principle and, if possible, with the same properties over a wide range of sizes. Modular products provide rationalization in the case a product range is to fulfill different functions and consequently many variants will have to be provided. Rationalization is possible in this case if the particular function variant is based on a combination of fixed individual parts and assemblies (function units). Pahl & Beitz (1996) define modular products as technical artifacts that fulfill various overall functions through a combination of distinct building blocks or modules. Because such modules can come in various sizes, modular products often involve size ranges. Among the expected benefits of using few basic elements are improved stability, more energy and focus upon each element yielding higher quality and better fundamental understanding, less risk in application, and more known factors in an integration effort. Ulrich & Tung (1991) defined three categories of modularity based on the interactions within a product. Component-swapping modularity occurs when two or more alternative basic components can be paired with the same modular components creating different product variants that belong to the same product family. Component-sharing modularity is the complementary case to component-swapping modularity. Various modular components share the same basic component to create different product variants belonging to different product families. Bus modularity is used when a module with two or more interfaces can be matched with any number of the components selected from a set of basic components. The module interfaces accept any combination of the basic components. Bus modularity allows variation in the number and location of the basic components in a product while component-swapping and component-sharing modularity allow only variation in the types of basic components.
A complementary source for an overview of modularization and product variety can be found in Blackenfelt (2001). Blackenfelt provides an overview of the literature on existing theories and terminologies for modular products and modularization as well as a discussion of how technical concepts relate to product modularity. The main focus is on applying a design structure matrix (DSM) approach to capture the relationships in the product. This is done both in terms of product component relations (functional and physical) and in terms of strategic relations. The strategic relations are added to the DSM based on the module drivers (Östgren, 1994) from the module indication matrix (MIM) (Erixon, 1998). The intention of the proposed approach (Blackenfelt, 2001) is to support consideration of the trade-offs between performance and cost through the integration and balancing of functional and strategic aspects. On the basis of the modular function deployment (MFD) method (Erixon, 1998), Stake (2000) aims to develop supporting tools for the modularization process. Stake (2000) proposes three tools: strategic module map (SMM), module driver hierarchy (MDH), and concepts by cluster analysis (CCA). Erixon et al. (1994) describes a practical approach to modularization including what the company can gain through modularization, how to choose an appropriate set of modules and how to create a generational plan for the product and the manufacturing system.
Design may be considered as the process of conversion of information (Pahl & Beitz, 1996). Huang & Kusiak (1998) focus our attention on the idea that the sufficiency of information is crucial in identifying modules. The type and amount of information available warrants the classification of modularity based on the phases of the design process, e.g. conceptual design or detailed design modularity. The modularity considerations may depend on the type of the product, e.g. mechanical, electrical, or software. Modularity refers to the decomposition of the architecture of a product family into distinct building blocks (modules) used to meet various functions of the products. The architecture of a product is the scheme by which its functional elements are arranged and interact.
Huang and Kusiak (1998) state, with reference to Sanchez (1993), that modular product design is an important form of strategic flexibility, i.e., flexible product designs allow a company to respond to changing markets and technologies by rapidly and inexpensively creating product variants derived from different combinations of the existing or new modular components. Modular product design supports the goals of the concurrent engineering that aims at reducing the product development time and cost by developing the modules concurrently. The decomposition approach aims at separating the product architecture into modules to be developed concurrently. In this way, products can be designed more effectively. To support this decomposition activity Huang and Kusiak (1998) provide an approach or method supported by three matrix representations: interaction matrix, suitability matrix, and modularity matrix.
Product development in the automotive industry of today is often based on a platform development strategy (Robertson and Ulrich, 1998). In short this means that several vehicle brands and models, each with many variants, is expected to be the outcome of the developed platform solutions. One of the challenges for a company that intend to develop products based on a common platform is the need to balance the two contradictory requirements for commonality and distinctiveness. Robertson & Ulrich (1998) formulated three key ideas underlying a platform planning process: (1) customers care about distinctiveness; costs are driven by commonality, (2) given particular product architecture, there is a trade-off between distinctiveness and commonality, and (3) product architecture dictates the nature of the trade-off between distinctiveness and commonality. The way variability is achieved defines the possible trade-offs that the product architecture can offer in terms of the balance between distinctiveness and commonality. Therefore, the ability to capture the nature and mechanisms for achieving this variability in a product description is important since it provides an important foundation for making trade-off decisions in the process of establishing the product architecture in a platform-based product development effort. Modular product systems are designed to allow for a variety of functions to be provided in the derivate products. Function identification therefore becomes a core issue in the design of modular product systems. The systems engineering discipline has a strong focus on function analysis and may therefore be important also to consider in the context of designing modular product systems.
Many actors are involved in the development of complex products. These actors are found both inside the organization responsible for the product and in other organizations that are involved in the development, e.g. as partners or suppliers. A recent study (von Corswant, 2003) was made of the network characteristics of the development activity in the automotive industry. There are two major aspects that influence the role of a product description that deserve to be highlighted. The first aspect is the cross-functional approach to product development. This situation is illustrated in Figure 29, which shows the cross-functional composition of a "module team" (von Corswant, 2003). The product to be developed is a common denominator that brings all these actors together to work towards a common goal. A reasonable assumption is therefore that a well-designed and implemented product description can play a central role in helping all these actors to move forward. The second aspect that deserves to be highlighted is the increased collaboration between actors in the development and supply chain. Parts are not only purchased from suppliers but are also to a large extent developed by the suppliers. Furthermore, not only parts are developed and delivered. The existence of system suppliers raises the level of involvement of a supplier both in the development process and in the production process. The collaborative structure in the development and supply chain is illustrated in Figure 30.
Figure 29: Composition of a module team (von Corswant, 2003).
Figure 30: A supply chain model used to categorize firms (von Corswant, 2003).
The increased level of responsibility of the product development for the actors in the development and supply chain increased the need for an effective and efficient interface between the actors that support the collaborative efforts. The substance of such a relationship is illustrated in Figure 31.
Figure 31: The substance of relationships (von Corswant, 2003).
The implications of this illustration of the relationship for the issues presented in this thesis are that the collaborative activities that occur between the actors in the development and supply chain must be supported by both an organizational structure and supporting resources. Shared definitions and descriptions of the emerging product are considered to be part of the resource collections and resource ties that form a part of the relationship. An interesting question that emerges from this view has to do with the assessment of what kind of product definition and description information exist in this kind of relationship today and evaluate that against some assessment of what information ought to be shared for successful (in terms of effectiveness and efficiency) collaborative development. It might also be interesting to assess to what extent the necessary information sharing is supported by systems and more formal procedures compared to the extent to which the necessary information is shared using more informal means. These questions are, however, outside the scope of the work presented here. In the context of the work presented in this thesis it is sufficient to conclude that the development and supply chains must be able to communicate extensive and shared information about the emerging product that is developed in a collaborative effort, and that a core product definition and description approach should consider this as an important requirement.
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