What is Forging Process?

Forging process is a combination of forging and stamping, which is a forming processing method that uses the hammer, anvil, punch of the forging machinery or through the die to apply pressure to the blank to produce plastic deformation to obtain the required shape and size of the workpiece.

Forging can be divided into cold forging and hot forging according to the temperature of the blank during processing. Cold forging is generally processed at room temperature, while hot forging is processed at a recrystallization temperature higher than that of the billet metal. Forging that is also sometimes carried out when it is in a heated state, but the temperature does not exceed the recrystallization temperature is called warm forging. However, this division is not completely uniform in production.

Cold forging: A forging process in which a metal material is pressed at room temperature.

Hot forging: A forging process in which a metal material is heated above the recrystallization temperature and below the solidus line.

Recrystallization temperature: 0.4 times the melting point of the metal can be taken as the recrystallization temperature.

For forged products, the cold forging process can obtain a better flatness, the hot forging process flatness is not well, and the temperature forging (the temperature of the metal material is between cold forging and hot forging) is medium.

Cold forging, also known as cold volume forming, is a manufacturing process and a processing method. It is basically the same as the cold stamping process. The cold forging process is also composed of three elements: materials, molds and equipment. It's just that the material in stamping is mainly plate, while the material in cold forging is mainly disc or wire.

Compared with hot forging, cold forging eliminates the need for expensive heating equipment, and at the same time has the advantages of saving useful materials and high processing accuracy, but it is also limited by process requirements, thus it has higher requirements for mold design and manufacturing, equipment pressure requirements, etc.

Advantages and disadvantages of hot forging

Advantages: If the temperature of the forging material is still much higher than the recrystallization temperature after the processing is completed, the grain will grow for a longer time, and coarser grains will be obtained, which can increase the fracture toughness (the crack growth rate is lower).

Disadvantages:

(1) Because of the high temperature operation, the danger to personnel safety and material safety is greater.

(2) The material is prone to oxidation at high temperatures, resulting in oxide scale, resulting in surface crust, poor finish and flatness.

(3) After the hot forging is completed, the forging material has cold shrinkage during the cooling process, which affects the accuracy of the forging size.

(4) The equipment and maintenance costs required for high-temperature forging are high.

Advantages and disadvantages of cold forging

Advantages:

(1) The forging material is not easy to produce oxide scale, and the surface finish is good.

(2) The precision of the forging size is better.

(3) Work hardening (strain hardening) will occur during machining, which can increase strength and hardness.

(4) The flow direction of the metal fiber of the forging can obtain a specific directionality.

(5) No heat treatment is required, so that the pollution problem is minimized.

(6) There is no need for heating costs, reducing production costs.

Disadvantages:

(1) The plasticity and toughness of the forging material are reduced, which is not conducive to subsequent processing.

(2) The deformation force required is greater than that of hot forging.

(3) Residual stress will occur inside the material.

(4) Metal grains will be deformed or broken.

(5) The directionality in the processing process may not be conducive to the future use of the product.