Classification of Forgings

Classification of Forgings
Classification by processing temperature
Forgings can be divided into cold forging warm forging and hot forging according to the temperature of the billet during processing. Cold forging is generally processed at room temperature, while hot forging is processed at a recrystallization temperature higher than that of the metal billet.
Classification by structure
The differences in the complexity of the geometric structure of forgings determine the significant differences between their forging process and mold design. Clarifying the type of forging structure is a necessary prerequisite for process design. The industry divides general forgings into three categories, each of which is further divided into three groups, totaling nine groups.
Class I - Forgings with similar two-dimensional dimensions (mostly circular/rotating, square or similar shape) in the horizontal direction when the main axis is vertically placed in the mold chamber for forming. The upsetting process is usually used when forging this type of forging. Divide into 3 groups based on the difference in forming difficulty.
Group I-1: Forgings formed by upsetting and slightly pressing, such as gears with little height variation between the wheel hub and rim.
Group I-2: forgings formed by extrusion and slightly upsetting, as well as extrusion, pressing and upsetting, such as universal joint fork, cross shaft, etc.
Group I-3: Forgings formed by composite extrusion, such as wheel hub shafts.
Class II - Straight long shaft forgings with the main axis horizontally placed in the die chamber for forming, and with a longer one-dimensional dimension in the horizontal direction. Divide into 3 groups based on the degree of difference in cross-sectional area of the vertical main axis.
Forgings with little difference in cross-sectional area between the vertical main axis of Group II-1 (the ratio of large cross-sectional area to small cross-sectional area is less than 1.6, and other equipment can be used for blank making).
Forgings with significant differences in cross-sectional area between the vertical main axis of Group II-2 (the ratio of large cross-sectional area to small cross-sectional area is greater than 1.6, and other equipment is required for blank making in front of them), such as connecting rods.
For forgings with forked/branched ends (one end or both ends) in Group II-3, in addition to determining the need for blank making based on the above two groups, it is necessary to reasonably design pre forging steps, such as casing forks.
The first and second types of forgings are generally divided into flat or symmetrical surface molds, while asymmetrical surface molds increase the complexity of the forgings.
Class III - Forgings formed by bending the main axis and lying horizontally in the mold chamber. Divide into 3 groups based on the direction of the main axis.
The main axis of Group III-1 is bent in the vertical plane (the parting surface is a flat and undulating surface or with a drop), but the plan view is a straight axis shape (similar to Class II), which generally does not require the design of specialized bending steps to form forgings.
The main axis of Group III-2 is bent in a horizontal plane (the parting surface is usually a plane), and bending steps need to be arranged to form the forging.
The main axis of Group III-3 is a forging with spatial bending (asymmetric curved surface parting).
There are also forgings with both or three types of structural features and higher complexity, such as most automotive steering knuckle forgings.