In the field of metal processing, forging process, as an important forming method, is widely used in many fields such as automotive, aerospace, machinery manufacturing, weapons industry and so on. It uses forging machinery to exert pressure on the metal billet to produce plastic deformation, so as to obtain forgings with certain mechanical properties, shape and size. In this paper, we will explain the depth of several commonly used forging process, including free forging, die forging, grinding ring and special forging, in order to provide reference for the relevant industry practitioners.

First, free forging

Free forging is a use of impact or pressure to make the metal in the upper and lower two against the iron (anvil) between the deformation of the processing method. It mainly has two forms of hand forging and mechanical forging. Hand forging relies on the skills and experience of craftsmen, suitable for small quantities, complex shapes of forgings. Mechanical forging is the use of forging hammers, hydraulic presses and other forging equipment on the billet forming process, suitable for mass production.

The advantage of free forging is that the process is flexible, applicable to a variety of shapes and sizes of forgings. At the same time, as the metal is subjected to three-way compressive stress in the forging process, its internal organisation is optimised and its mechanical properties are improved. However, the production efficiency of free forging is relatively low, and the craftsman's skills are more demanding.

Second, die forging

die forging is a kind of metal billet placed in a certain shape of the forging die chamber, through the application of pressure to make it deformed by pressure and obtain the forging process. According to the structure of the forging die and forging temperature, die forging can be divided into open die forging, closed die forging, hot die forging, warm forging and cold forging.

The advantages of die forging are high production efficiency, precise size of forgings, high surface finish, and high material utilisation. In addition, die forging can also improve the internal organisation of the metal, improve mechanical properties. However, die forging has higher requirements for moulds, and the design and manufacturing cycle of moulds is longer and more costly.

In the die forging process, hot die forging is one of the most commonly used methods. It is suitable for the production of large and complex shaped forgings. In hot die forging, the metal billet is heated to a certain temperature and then forged to reduce the deformation resistance and improve plasticity. Warm forging and cold forging is the future direction of die forging, they can improve the accuracy and surface quality of forgings to a certain extent, while reducing material waste.

Third, grinding ring

grinding ring is a special equipment through the ring mill to produce different diameters of ring-shaped parts of the process method. It is suitable for the production of automobile hubs, train wheels and other wheel-shaped parts. Grinding process has the advantages of high production efficiency, high material utilisation, accurate size of forgings and so on.

In the ring grinding process, the metal billet is placed in the mould of the ring grinding machine, through the rotation of the mould and the pressure exerted, so that the metal produces continuous local plastic deformation, so as to achieve the wall thickness reduction, diameter expansion and cross-section profile forming. Grinding process on the higher requirements of the mould, the need for accurate design and manufacture of moulds to ensure that the size and shape of the forgings precision.

Fourth, special forging

special forging, including roll forging, wedge rolling, radial forging, liquid die forging and other process methods. These processes are suitable for the production of certain special shapes of parts.

1. Roll forging: roll forging is a use of two or more rotating rolls on the metal billet for continuous local plastic deformation process. It is suitable for the production of slender bars and parts with complex cross-sectional shapes. Roll forging can significantly reduce the subsequent forming pressure, improve material utilisation.

2. wedge cross rolling: wedge cross rolling is a use of wedge-shaped moulds on the metal billet transverse rolling process. It is suitable for the production of shaft parts and gears. Wedge rolling can significantly improve productivity and reduce material consumption.

3. Radial forging: radial forging is a use of radial moulds on the metal billet for local plastic deformation process. It is suitable for the production of large forgings and thick-walled tubes and so on. Radial forging can improve the mechanical properties of forgings and dimensional accuracy.

4. liquid die forging: liquid die forging is a kind of forming method between die casting and die forging. It is suitable for the production of complex thin-walled parts and parts with special properties. Liquid die forging combines the advantages of casting and forging, can significantly improve the mechanical properties of forgings and surface quality.

Fifth, application and development of forging technology

Forging process has an important position in the machinery manufacturing industry. It can not only provide blanks for mechanical parts, but also improve the internal organisation of the metal, improve the mechanical and physical properties of the metal. Therefore, the forging process is widely used in metallurgy, mining, automotive, tractor, harvesting machinery, petroleum, chemical, aviation, aerospace, weapons and other industrial sectors.

With the progress of science and technology and the development of manufacturing industry, the forging process is also constantly innovated and improved. On the one hand, people improve the forging efficiency and quality of forgings by improving the forging equipment and process methods; on the other hand, people are also exploring new forging materials and forming technology to meet the demand for forging performance and quality in different fields.