ABSTRACT
Modern shaping processes for metals can be divided into hot- and cold-working operations. The former tend to be used wherever possible since less power is required and working can be carried out more rapidly. Cold-working processes, on the other hand, are used in the final stages of shaping some materials, so that a high-quality surface finish can be obtained or suitable strength and hardness developed in the material. The simplest and most ancient metal-working process is that of hand-forging, mentioned earlier. With the aid of simple tools called swages, the smith can produce relatively complex shapes using either a hand- or power-assisted hammer. The main advantage of hot-pressing over drop-forging is that the mechanical deformation takes place more uniformly throughout the workpiece and is not confined to the surface layers, as it is in drop-forging. A mechanised process somewhat similar to spinning, but known as flow-turning, is used for the manufacture of such articles as stainless-steel or aluminium milk-churns.
