According to the forging temperature, it can be divided into hot forging, warm forging and cold forging.According to the forming mechanism, forging can be divided into free forging, die forging, rolling ring and special forging.

1. Open Die forging
Refers to the machining method of forging with a simple universal tool, or directly applying external force to the blank between the upper and lower anvil of the forging equipment, so that the blank is deformed and the required geometry and internal quality are obtained.Forgings produced by free forging are called free forgings.Free forging is mainly to produce small quantities of forgings, using forging hammer, hydraulic press and other forging equipment to form the blank processing, qualified forgings.The basic processes of free forging include upsetting, drawing, punching, cutting, bending, twisting, shifting and forging.Free forging takes the form of hot forging.

2. Die forging
Die forging is divided into open die forging and closed die forging.The metal blank is obtained by pressing and deforming in the forging chamber with a certain shape.Die forging can be divided into hot die forging, warm forging and cold forging.Warm forging and cold forging are the future development direction of die forging and represent the level of forging technology.

According to the material, die forging can also be divided into ferrous metal die forging, non-ferrous metal die forging and powder products forming.As the name suggests, it is the material is carbon steel and other ferrous metals, copper and aluminum and other nonferrous metals and powder metallurgy materials.
Extrusion should be attributed to die forging, can be divided into heavy metal extrusion and light metal extrusion.
Closed die forging and closed upsetting are two advanced processes of die forging.It is possible to finish complex forgings with one or more processes.Since there is no flash, the forgings have less stressed area and require less load.However, care should be taken not to limit the blank completely, so that the volume of the blank should be strictly controlled, the relative position of the forging die controlled and the forging measured, in an effort to reduce the wear of the forging die.

3. Grinding ring refers to the ring parts with different diameters produced by special equipment ring grinding machine. It is also used to produce wheel shaped parts such as car hub and train wheel.

4.Special forging special forging includes roll forging, cross wedge rolling, radial forging, liquid die forging and other forging methods, which are more suitable for the production of some special shapes of parts.For example, roll forging can be used as an effective preforming process to greatly reduce the subsequent forming pressure.Cross wedge rolling can produce steel ball, transmission shaft and other parts;Radial forging can produce large forgings such as barrel and step shaft.
According to the deformation limitation characteristics of the lower dead point, the forging equipment can be divided into the following four forms:

a. Form of limited forging force: hydraulic press that directly drives the slider.

b, quasi-stroke limit: oil pressure drive crank linkage mechanism of the oil press.

c, stroke limit: crank, connecting rod and wedge mechanism to drive the slider mechanical press.

d. Energy limitation: screw and friction press with screw mechanism.In order to achieve high precision attention should be paid to prevent overload at the lower dead point, forging front bridge control speed and die position.Because these will have an impact on the forging tolerance, shape accuracy and forging die life.In addition, in order to maintain the accuracy, we should also pay attention to adjust the slider guide clearance, ensure the stiffness, adjust the dead point and the use of auxiliary transmission measures.

 From:168 forgings net