Forging is methods to shape metal by applying forces.
Forging is the traditional method to form metal pieces. Back in the days, it was done by a smith using hammers and anvils. Nowadays it has changed totally; the most common tools are presses and industrial hammers, usually powered by compressed air, electricity or hydraulics. In addition, other processes like bending or cutting are also common.
By using large forces the material's structure is changed. The binding between the metal grains changes in a way that gives the material good stiffness and durability, usually better than the ones achieved when machining or casting.
Forging is divided in two main categories; drawn out when the component's length increases and upset when the length decreases. There is also a third category when a component is squeezed between dies. There are about ten common forging processes within these categories, all of which use tools that presses or strikes the workpiece to change its shape.
Furthermore, the forging can be carried out when the workpiece is cold, warm or hot, depending on the material and the specifications. For example, iron and steel are almost always hot forged.
Forging almost always requires subsequent machining.