3e2a1b56-dafb-454d-87ad-86adea3e7b86

Chapter 5 The design of products and services 131
Simultaneous development
Sequential approach
to design
Simultaneous or
concurrent approach
to design
Simultaneous (or
concurrent) engineering
Earlier in the chapter we described the design process as essentially a set of individual,
predetermined stages. Sometimes one stage is completed before the next one commences.
This step-by-step, or sequential, approach has traditionally been the typical form of product/
service development. It has some advantages. It is easy to manage and control design projects
organized in this way, since each stage is clearly defined. In addition, each stage is
completed before the next stage is begun, so each stage can focus its skills and expertise on
a limited set of tasks. The main problem of the sequential approach is that it is both timeconsuming
and costly. When each stage is separate, with a clearly defined set of tasks, any
difficulties encountered during the design at one stage might necessitate the design being
halted while responsibility moves back to the previous stage. This sequential approach is
shown in Figure 5.10(a).
Yet often there is really little need to wait until the absolute finalization of one stage
before starting the next. For example, perhaps while generating the concept, the evaluation
activity of screening and selection could be started. It is likely that some concepts could be
judged as ‘non-starters’ relatively early on in the process of idea generation. Similarly, during
the screening stage, it is likely that some aspects of the design will become obvious before the
phase is finally complete. Therefore, the preliminary work on these parts of the design could
be commenced at that point. This principle can be taken right through all the stages, one stage
commencing before the previous one has finished, so there is simultaneous or concurrent
work on the stages (see Fig. 5.10(b)). (Note that simultaneous development is often called
simultaneous (or concurrent) engineering in manufacturing operations.)
Figure 5.10 (a) Sequential arrangement of the stages in the design activity; (b) simultaneous
arrangement of the stages in the design activity