Based on 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, ring rolling, and special forging.
　　1. Free forging. This refers to a processing method in which simple, general-purpose tools are used, or external force is directly applied to the billet between the upper and lower anvils of forging equipment, causing the billet to deform to obtain the required geometric shape and internal quality of the forging. Forgings produced using the free forging method are called free forgings. Free forging mainly produces forgings with small batch sizes, using forging equipment such as forging hammers and hydraulic presses to shape the billets and obtain qualified forgings. The basic processes of free forging include upsetting, drawing, punching, cutting, bending, twisting, shifting, and forging welding. Free forging adopts hot forging methods.
　　2. Die forging. Die forging is divided into open-die forging and closed-die forging. Metal billets are deformed under pressure in a die cavity with a certain shape to obtain forgings. Die forging is generally used to produce parts with small weight and large batch sizes.
　　Die forging can be divided into hot die forging, warm forging, and cold forging. Warm forging and cold forging are the future development directions of die forging, and also 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 product forming. As the name suggests, the materials are carbon steel and other ferrous metals, copper, aluminum and other non-ferrous metals, and powder metallurgy materials.
　　Extrusion belongs to die forging and can be divided into heavy metal extrusion and light metal extrusion.
　　Closed-die forging and closed-die upsetting are two advanced processes of die forging. Because there is no flash, the material utilization rate is higher. Complex forgings can be finished with one or several processes. Because there is no flash, the stress area of the forging is reduced, and the required load is also reduced. However, it should be noted that the billet cannot be completely restricted. Therefore, the volume of the billet, the relative position of the die, and the measurement of the forging should be strictly controlled to reduce die wear.
　　3. Ring rolling. Ring rolling refers to the production of ring-shaped parts with different diameters using special equipment, ring rolling machines, which are also used to produce wheel-shaped parts such as automobile hubs and train wheels.
　　4. Special forging. Special forging includes roll forging, wedge cross rolling, radial forging, liquid die forging, etc. These methods are more suitable for producing parts with special shapes.
　　For example, roll forging can be used as an effective pre-forming process to significantly reduce the subsequent forming pressure; wedge cross rolling can produce steel balls, transmission shafts, etc.; radial forging can produce large gun barrels, stepped shafts, etc.