Forgings are deformed during the cold forging process and are work-hardened so that the forging die is subjected to a large load. For this reason, high strength forging dies are required, with hard lubricating films to prevent wear and bonding. In addition, intermediate annealing is required to prevent cracking of the blank to ensure the required deformation capacity. To maintain good lubrication, the blanks can be phosphated. Due to the continuous processing of bars and coils, it is not yet possible to lubricate the cross section, so the possibility of using phosphate lubrication methods is being investigated.

Forgings can be divided into free forging, cold heading, extrusion, die forging, closed forging and closed forging according to the movement of the cast billet. Closed forgings and closed upsetting forgings are free of flying edges and have a high material utilisation rate. The finishing of complex forgings can be accomplished in one or a few steps. In the absence of flying edges, the load-bearing area of the forging is reduced and the required load is lowered. However, in cases where the blank cannot be completely limited, the volume of the blank should be strictly controlled, the relative position of the die should be controlled and the forging should also be checked to minimise wear on the forging die.

The forging process is further divided into pendulum rolling, pendulum forging, roller forging, wedge cross rolling, ring rolling and rolling according to its mode of die movement. Pendulum roller type, pendulum rotary forgings and rolls can be finely forged. Rolling and cross-rolling can be used as a pre-process for slender materials to improve material utilisation. The use of free forging and other rotary forging process, but also partial forming, with a smaller forging size conditions to achieve forging processing capabilities of this forging method, including free forging, in the processing process, the material away from the die surface close to the free-form surface, and thus difficult to ensure its accuracy, therefore, the use of computer control of forging die movement direction and rotary forging process, you can obtain complex shapes, high precision products, thereby improving its processing capability.

When the temperature exceeds 300-400°C (steel blue embrittlement zone) 700°C-800°C, the resistance to deformation is significantly reduced and the deformation capacity is significantly increased. Forging according to different temperature zones, forging quality and forging processing process requirements, can be divided into cold forging, warm forging, hot forging three kinds of forming temperature zone. It turns out that this temperature range is divided into no strict boundaries, in general, in the forging process with recrystallization temperature zone called hot forging, and at room temperature without heating the forgings called cold forging.

Cold forging process, forging size change is not significant. Below 700 ℃ forging processing, oxidation skin formation less, the surface without decarburisation phenomenon. Therefore, as long as the cold forging deformation can be made to reach the energy range, you can obtain good dimensional accuracy and surface finish. If you control the temperature and lubrication cooling, can be in 700 ℃ warm forging, in order to obtain a higher precision. When hot forging, deformation energy is small, deformation resistance is small, can forging processing complex shape of large forgings.