Forging is a processing method that uses forging machinery to apply pressure to metal blanks to cause plastic deformation to obtain forgings with certain mechanical properties, certain shapes and sizes. It is one of the two major components of forging (forging and stamping). Forging can eliminate defects such as as-cast porosity produced in the metal smelting process and optimize the microstructure. At the same time, due to the preservation of complete metal flow lines, the mechanical properties of forgings are generally better than castings of the same material. For important parts with high load and severe working conditions in related machinery, forgings are mostly used, except for plates, profiles or weldments that can be rolled with simpler shapes. The forgings used in most industries are hot forging. Warm forging and cold forging are mainly used for forging parts such as automobiles and general machinery. Warm forging and cold forging can effectively save materials.

According to the forming mechanism, forging can be divided into free forging, die forging, ring rolling and special forging.

1. Free forging. Refers to the processing method of using simple general-purpose tools or directly applying external force to the blank between the upper and lower anvils of the forging equipment to deform the blank to obtain the required geometric shape and internal quality of the forging. Forgings produced by free forging method are called free forgings. Free forging mainly produces forgings with small batches. Forging equipment such as forging hammers and hydraulic presses are used to form blanks to obtain qualified forgings. The basic process of free forging includes upsetting, drawing, punching, cutting, bending, twisting, shifting and forging. Free forging adopts hot forging method.

2. Die forging. Die forging is divided into open die forging and closed die forging. Metal blanks are deformed under pressure in a forging die chamber with a certain shape to obtain forgings. Die forging is generally used to produce parts with small weight and large batches.