Set-based concurrent engineering framework and principles

The most effective explanation of the concept is provided in Sobek et al. (1999) who identified a large number of SBCE principles and structured them into a coherent framework as illustrated in Figure 6.3. Moreover, the authors supply practical examples from Toyota, Chrysler, Denso and Delphi.

142 Figure 6. 3: Principles of Set-based concurrent engineering

Source: Researcher´s own construction based on Sobek et al. (1999:73) The idea behind Figure 6.3 is to illustrate three key principles and nine concepts identified by Sobek et al. (1999) which have been briefly summarized, as follows:

SBCE Principle 1: Map the design space

The main goal behind this principle is deep understanding of the set of design alternatives. This principle deals with the mapping of design space, possibilities, feasibilities and costs for systems and subsystems under construction. Each functional department involved in the development programme simultaneously defines feasible

regions such as styling design alternatives, body engineering alternatives,

manufacturing capability etc. After functional groups have developed sets of feasible alternatives, the decision-making process follows: this is based on exploration of trade-

off curves. The data is extracted from prototypes and simulations - and from the tests

performed on a specific number of tested parts in order to establish mathematical relationships between parameters and performance. Toyota engineers evaluate many different alternatives and communicate sets of ideas and possibilities to all functional departments involved in the project. Taking into account perspectives from all functions, the optimal solution for the overall system is then selected.

SBCE Principle 2: Integrate by intersection

Engineering groups develop more than one alternative for their subsystems in parallel. Subsequently, they identify intersections of different functions in order to perform

•Define feasible regions

•Explore trades-off by designing multiple alternatives •Communicate sets of possibilities

Map the design

space

•Look for intersections of feasible sets •Impose minimum constraint •Seek conceptual robustness

Integrate by

intersection

•Narrow sets gradually while increasing detail •Stay within sets once committed

•Control by managing uncertainty at process gates

Establish

feasibility before

commitment

143

integration of the whole system. All parties involved strive to determine the best

solutions that will help to optimize total system performance. For a successful integration maximum flexibility for explorations and minimum constraint imposed are necessary. This enables engineers to make last-minute modifications and allows room for optimization and adjustment. The focus in the design is on the modular structure of the component with the robust core and separate peripheral parts easily integrated with other functional sets of components. The benefit of conceptual robustness is significant reduction of development time.

SBCE Principle 3: Establish feasibility before commitment

This third principle describes the heart of Toyota´s set-based process and their successful development system. The functional departments involved in the process explore multiple designs in parallel in order to understand all design alternatives and interactions. Before design teams make the final decision they seek to understand all relevant considerations. The teams narrow their sets in parallel and gradually eliminate inappropriate alternatives until the final solutions remain. Within this process they gradually converge on a single best solution that enables optimization of the overall system. One of the important rules of their narrowing process is that teams must adhere

to the sets once they are committed and so avoid unexpected changes. The whole PD

process is managed through a series of gates where the status of every function is reported and knowledge shared, thus reducing levels of uncertainty. This approach provides better control over the process: with more milestones or gates, shorter time lags and increased testing at subsystem level, overall development lead time can be reduced.

6.3.4 Linking the theory with the real world

Principle 2 in a LPD framework is a mix of various theoretical concepts. This section which is central to the structure of this thesis has focused on CE and more specifically on the SBCE concept, both key elements of the LPDS. The detailed information provided supports implementation of the SBCE system in a real organization. However, the researcher´s perception is that any organization considering adoption of SBCE needs to make an effort to investigate which approach is more suitable for their circumstances. The traditional engineering approach and SBCE both have advantages and disadvantages. Table 6.2 below provides a brief summary of both engineering approaches.

144 Table 6. 2: Comparison of engineering approaches

Source: Researcher´s own construction based on the extensive literature review

One must be aware that principles outlined in the SBCE framework are not prescriptions or simple recipes to follow. Toyota applies these principles for each design project differently, depending on its chief engineer. The key to success is the implementation of the whole system and not just implementation of a few isolated principles. In essence set-based and system thinking are powerful cultural aspects of Toyota’s methodology. For many companies the transformation towards a lean process will require a huge cultural adaptation as these principles work against the habits and ways of thinking that are embedded in traditional development organizations.

6.4 PRINCIPLE 3: CREATE A LEVELED PRODUCT DEVELOPMENT PROCESS