What kind of process requires forging and pressing

Forging is a processing method that uses forging machinery to apply pressure to metal billets, causing them to undergo plastic deformation, in order to obtain forgings with certain mechanical properties, shapes, and sizes. Forging and stamping belong to plastic processing properties, collectively referred to as forging.

Forging is a commonly used forming method in mechanical manufacturing. Forging can eliminate the casting porosity and welding holes of metals, and the mechanical properties of forgings are generally better than castings of the same material. For important parts with high loads and severe working conditions in machinery, forgings are often used, except for simple shaped plates, profiles, or welded parts that can be rolled.

Forging can be divided into cold 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 temperature higher than the recrystallization temperature of the billet metal. Sometimes forging that is still in a heated state but does not exceed the recrystallization temperature is called warm forging. However, this division is not completely uniform in production. The recrystallization temperature of steel is about 460 ℃, but 800 ℃ is commonly used as the dividing line, and those above 800 ℃ are hot forged; Between 300 and 800 ℃ is called warm forging or semi hot forging.

Forging can be divided into free forging, die forging, cold heading, radial forging, extrusion, forming rolling, roll forging, rolling, etc. according to the forming method. The deformation of the billet under pressure is basically not restricted by external factors, which is called free forging or open forging; The deformation of billets in other forging methods is limited by the mold, which is called closed mode forging. The forming tools such as forming rolling, roll forging, and rolling have relative rotational motion with the billet, which gradually applies pressure and forms the billet point by point, hence it is also known as rotary forging.

The forging materials mainly consist of carbon steel and alloy steel with various compositions, followed by aluminum, magnesium, copper, titanium and their alloys. The original states of materials include bar, ingot, metal powder, and liquid metal. Generally, circular or square bar materials are used as blanks for small and medium-sized forgings. The grain structure and mechanical properties of the bar material are uniform and good, with accurate shape and size, good surface quality, and easy to organize for mass production. As long as the heating temperature and deformation conditions are reasonably controlled, high-quality forgings can be forged without significant forging deformation.

Ingots are only used for large forgings. Ingot is a cast structure with large columnar crystals and loose centers. Therefore, it is necessary to crush the columnar crystals into fine grains through large plastic deformation, and compact them loosely in order to obtain excellent metal structure and mechanical properties.

Powder metallurgy preforms formed by pressing and firing can be made into powder forgings by non flash forging in the hot state. The density of forging powder is close to that of general die forgings, with good mechanical properties and high precision, which can reduce subsequent cutting processing. The internal structure of powder forgings is uniform without segregation, and can be used to manufacture small gears and other workpieces. However, the price of powder is much higher than that of general bar materials, which limits its application in production.

By applying static pressure to the liquid metal poured into the mold cavity, it can solidify, crystallize, flow, undergo plastic deformation, and form under pressure to obtain the desired shape and properties of the forging. Liquid metal forging is a forming method between die casting and die forging, especially suitable for complex thin-walled parts that are difficult to form by general die forging.

Different forging methods have different processes, among which the process flow of hot forging is the longest, generally in the order of: billet cutting; Heating of forging blanks; Roll forging blanks; Forging forming; Cutting edges; Intermediate inspection, checking the size and surface defects of forgings; Forging heat treatment is used to eliminate forging stress and improve metal cutting performance; Cleaning, mainly to remove surface oxide scale; Correction; Inspection: Generally, forgings need to undergo appearance and hardness testing, while important forgings also need to undergo chemical composition analysis, mechanical properties, residual stress testing, and non-destructive testing.

Forging is a combination of forging and stamping, which is a forming and processing method that uses the hammer head, anvil block, punch or mold of forging machinery to apply pressure to the billet, causing plastic deformation and obtaining the desired shape and size of the workpiece.

In forging processing, the billet undergoes significant plastic deformation as a whole, with a large amount of plastic flow; In stamping processing, the blank is mainly formed by changing the spatial position of the area of each part, and there is no plastic flow over a large distance inside. Forging is mainly used for processing metal parts, and can also be used for processing certain non-metallic materials such as engineering plastics, rubber, ceramic blanks, brick blanks, and forming composite materials.