TABLE OF CONTENTS 
It is mechanical design with which we are primarily concerned here; it deals with the physical principles, the proper functioning and the production of mechanical systems. This does not mean that we ignore industrial design, which speaks of pattern, color, texture, and (above all) consumer appeal but that comes later. The starting point is good mechanical design, and the ways in which the selection of materials and processes contribute to it.
Our aim is to develop a methodology for selecting materials and processes that is design-led; that is, the selection uses, as inputs, the functional requirements of the design. To do so we must first look briefly at design itself. Like most technical fields it is encrusted with its own special jargon, some of it bordering on the incomprehensible. We need very little, but it cannot all be avoided. This chapter introduces some of the words and phrases the vocabulary of design, the stages in its implementation, and the ways in which materials selection links with these.
The starting point is a market need or a new idea; the end point is the full product specification of a product that fills the need or embodies the idea. A need must be identified before it can be met. It is essential to define the need precisely, that is, to formulate a need statement, often in the form: "a device is required to perform...
