Essential Manufacturing

6Materials for Manufacture

6.1 Introduction

A design and manufacturing engineer must have a good knowledge of the types and properties of materials from which a product can be manufactured. The material must not be so expensive as to make the product uncompetitive in the market place, yet it must possess all the characteristics necessary for the functioning of the product. Factors such as cost, strength, hardness and how easily it can be worked must be considered carefully by the designer. Although there is already a wide range of materials available, research and development ensure that new ones are constantly being created. In plastics alone it is estimated that hundreds of new variants are developed each year. Advances in various areas of technology can often stimulate the need for new materials. For example, the possibility of building spacecraft created a requirement for materials, including metals, which could withstand extremes of temperature, pressure and vibration.

We will mainly concern ourselves with metals and polymers that are the most common engineering materials. Other materials, such as composites and ceramics, are also noted. These materials are gaining in importance as more is learned about how to manipulate their structures to obtain desired properties.

One way of grouping materials is shown in Figure 6.1, that is, into metals and non‐metals. Metals are essentially chemical elements, such as iron, copper, gold and aluminium, or alloys of elements, such as steel ...