Forging is a method in which a material is shaped by plastic deformation by the application of compressive force at its plastic deformation temperature.    This force is applied by a hammer, as in the case of a blacksmith, or by a mechanical or hydraulic press.

Forging is the oldest metalworking processes known to man.  The grain structure of the material is recreated.  This leads to improvement in the properties such as strength, toughness and ductility.

Forging processes can be classified into three categories.  They are

1. Drawn out processes
Here the length increases while the cross-section reduces.

2. Upset processes
Here the length decreases while the cross-section increases

3. Squeezing in processes
Produces multi-directional flow. Length and Cross-section changes are different at different parts.

Forging can be done above the recrystallization temperature, where it is called hot forging or below the recrystallization temperature, where it is called cold forging.