The Design Process - Medical Device Design: Innovation from Concept to Market - page 31

Where, or when, the need comes from is often a matter of debate…but it always exists. In
essence it comes from five main sources (as described in Chapter 1). The first source is a
customer who specifically asks for something, or from the marketing department/sales force
who will have spoken to their customers - this is immediate need ; the second source also
comes from the marketing department and relates to “copying” someone else - scavenging
need ; the third relates to market research predicting a trend and formulating a prospective
need ; the fourth comes from research and development where a disruptive technology has
invented a need for its use - this is also a prospective need ; the final source is directly from
postmarket surveillance and relates to the evolution of the device - evolutionary need . The
main thing to ensure is that the need is documented and accepted - this documentary evidence
of a need may be called a brief .
While this seems logical, it implies a “wait and see” philosophy. It suggests there is little
space for alterations, changes of mind, and changes of demands. Backward and forward
arrows accommodate feedback between phases. The process waits for problems to arise
before they are discussed. This can result in eddies: loops in which the designer and their
partners get stuck.
Figure 3.5 attempts to illustrate these phases. The first phase can be considered a clarification
phase. That is, this phase enables the designer (or design team) to make themselves fully
aware of the need and the environment in which the need operates. It also gives the designer
time to talk to the end-users (et al.). All of this is necessary in order to develop a full
specification before going on to the conceptual design phase. This phase enables the designer
to develop initial ideas from which to select a single design to go through to the embodiment
phase, where a final prototype is developed. Once accepted, the prototype can go through to
design for manufacture (detailed design) and final documentation.
It is now pertinent to introduce Pugh's 5 Total Design model ( Figure 3.6 ). Once again, this is a
linear approach. However, Pugh took the concept of a product specification to a higher level.
He identified that if time is spent developing a good specification then all else will fall into
place.
Unlike the original model of Pahl and Beitz, Pugh incorporated manufacturing into the design
process. For us this is an important step towards our design model. Nowadays there are terms
such as D-4-X and Design-for-Manufacture. These demonstrate how much of the tail has
been brought into the design process.
While these models are worthy, in reality they do not give a full picture of actual activity.
They visualize the processes but not the activities. To this extent I shall present a didactic
model.
5 Pugh proposed the concept of “Total Design” in his seminal topic of the 1990s.