Essential Manufacturing

10Deformation Processes

10.1 Introduction

There are at least three ways in which to classify deformation processes. One is to use the terms ‘bulk’ deformation and ‘sheet’ forming. Bulk deformation implies that the ratio of the surface area to the volume is relatively small and that the process will significantly alter the cross sectional area and shape; an example of this is forging. It is this bulk deformation that is considered in this chapter, it is an important process as it can provide fine control over the grain structure of a component and hence impart directional strength properties. Sheet forming involves changing the shape of material without significantly changing the cross sectional area; examples of this are blanking, bending and drawing and these are considered in Chapter 11.

Another classification uses the terms ‘primary’ and ‘secondary’ deformation. Primary deformation signifies the changing of shape of a piece of material from its cast ingot form into another shape. Examples of this would be rolling, forging and extrusion to produce standard shapes such as slabs, billets or rods. Secondary forming processes take the output from the primary process and further work the material to produce a finished or semi‐finished product. These processes may again be rolling, forging or extrusion, but this time typical products would be foil, bolts or window frames.

A third classification relates to the temperature at which the deformation work is carried out. Thus a deformation ...