In general, high loads and harsh working conditions of the important parts of the machinery, in addition to simple shapes that can be rolled, profiles or welded parts, basically use forging workpiece.

Forging is a use of forging machinery to apply pressure to the metal billet, so that it produces plastic deformation in order to obtain a certain mechanical properties, a certain shape and size of the forging processing method. Through forging, the cast looseness of the metal and welded holes can be eliminated, and the mechanical properties of forged parts are usually superior to those of castings of the same material.

Classification and characteristics of forging process

According to the forging temperature, the forging technology can be divided into hot forging, warm forging and cold forging.

The starting recrystallisation temperature of steel is about 727°C, but the industry generally adopts 800°C as the dividing line, and those higher than 800°C are hot forging; those between 300 and 800°C are called warm or semi-hot forging, and those forged at room temperature are called cold forging. Most of the industry forgings are processed by hot forging, warm forging and cold forging are mainly used in automobiles, general machinery and other parts of the forging, warm forging and cold forging process can achieve effective material saving.

According to the different production tools, the forging technology can be divided into free forging, die forging, ring grinding and special forging.

Free Forging

Free forging refers to the use of simple general-purpose tools, or in the forging equipment between the upper and lower anvil iron directly on the billet to exert external force, so that the billet deformation and obtain the desired geometry and internal quality of the forgings processing methods.

Free forging are taken to the hot forging method. The basic processes of free forging include upsetting, elongation, punching, cutting, bending, twisting, misalignment and forging, etc. The basic processes of free forging include upsetting, elongation, punching, cutting, bending, twisting, misalignment and forging. Free forging is based on the production of a small batch of forgings, the use of forging hammers, hydraulic presses and other forging equipment on the billet forming process, to obtain qualified forgings.

Die forging

Die forging refers to the metal billet in a certain shape of the forging die chamber pressure deformation and obtain forgings, die forging is generally used in the production of small weight, batch size parts. Die forging can be divided into hot forging, warm forging and cold forging. Warm forging and cold forging are the future development direction of die forging, which also represents the level of forging technology.

Ring grinding

Ring grinding refers to the production of ring-shaped parts of different diameters by special equipment ring grinding machine, also used to produce automotive wheel hubs, train wheels and other wheel-shaped parts.

Special Forging

Special forging includes roll forging, wedge cross rolling, radial forging, liquid die forging and other forging methods. These methods are more suitable for the production of certain special shaped parts. For example, roll forging can be used as an effective pre-forming process, significantly reducing the subsequent forming pressure; wedge rolling can produce steel balls, drive shafts and other parts; radial forging can produce large gun barrels, step shafts and other forgings.

According to the movement of the forging die, forging can be divided into pendulum rolling, pendulum rotary forging, roll forging, wedge cross rolling, rolling ring and oblique rolling and other ways.

In the field of machinery manufacturing, turbine generator shafts, rotors, impellers, blades, ring guards, large hydraulic press columns, high-pressure cylinders, rolling mill rolls, crankshafts, connecting rods, gears, bearings, as well as the defence industry, artillery, etc., on the stress on the large, demanding and important parts, are used in forging production.

Therefore, forging production is widely used in metallurgy, mining, automobiles, tractors, harvesting machinery, petroleum, chemical industry, aviation, aerospace, weapons and other industrial sectors, that is, in daily life, forging production also has an important position. In a sense, the annual output of forgings, die forging parts in the proportion of total forging production, as well as the size of forging equipment and the number of indicators, to a certain extent, can reflect a country's industrial level.