The overall function of a product is the relationship between its inputs and output. The function
of the product can be further broken down to subfunctions that identify purposive actions
that the product is meant to perform. Whereas requirements, as set by the customer, are
‘wish-lists’ that describe what the product should do, functions are solution-neutral engineering
actions that the product will perform. This stage is important in several ways. The
first is that this stage signifies converting wishes into engineering terminology which is more
relevant to the design team. The second is that it is important to realize that functions remain
solution-neutral, and hence, it is still a means to further ascertain the problem. It may seem
that a lot of time is spent at identifying and refining the problem. At first sight; this may seem
like an inefficient process. This is so much so that some inexperienced designers become
impatient and decide to short-cut or even skip this stage and try to suggest different concepts
or solutions immediately. The thing to remember here is that it is unlikely that the best solution
can be provided to something where the best definition of the problem is not available.
Functions should consider ‘what’ the product does (the problem) and not ‘how’ it does
it (solution). A function involves the following two components.