Powder metallurgy is a processing method that uses metal powder as raw material and presses and sinters it to make various products. The powder metallurgy process consists of three main steps. First, the main component materials are decomposed into powders composed of many fine particles; then, the powder is loaded into the mold cavity and a certain amount of pressure is applied to form the required part shape and shape. size of the compact; finally, the compact is sintered. The essential advantages of the powder metallurgy parts production process are the final forming capabilities of the parts and high material utilization.

Sintering

The operation of heating green-pressed parts to an appropriate temperature to increase their mechanical strength and hardness is called sintering. During the sintering process, the grain interface is first formed, which in turn causes the recrystallization of the grains. The high temperature improves the plasticity of the metal surface and establishes a layer of liquid network structure, which can improve the mechanical interlocking properties between each other. In addition, Dissolved gases in metal can also be driven out at high temperatures. As for the sintering temperature, it is usually below the melting point of the main component metal, and the sintering time is about 20-40 minutes. In addition, during the sintering process, in order to avoid oxidation of the powder in contact with the atmosphere, reduction can be used Use neutral gas or nitrogen to prevent the formation of harmful oxide layers during high heat. In addition, after sintering, the size of green pressed parts may increase or decrease slightly due to factors such as product shape, particle size, and distribution, chemical composition, sintering operation conditions, pressure levels, etc.

Hot Pressing

The hot pressing method is a processing method that simultaneously completes the pressing and sintering of powder in a mold. It is often used in the manufacture of tungsten carbide tool materials. This method has the advantages of improving the strength, hardness, and precision of the product, but because heating is performed while pressurizing, the mold used must be of heat-resistant material, and the heating time and the duration of the heating are difficult to control; in addition, during When processing high-temperature alloys, graphite molds must be used. However, due to the very low strength of the graphite mold, it can only be used once and consumes a lot of money.

 

Heat Treatment

Heat treating (or heat treatment) is a group of industrial, thermal, and metalworking processes used to alter the physical, and sometimes chemical, properties of a material. The most common application is metallurgical. Heat treatments are also used in the manufacture of many other materials, such as glass. Heat treatment involves the use of heating or chilling, normally to extreme temperatures, to achieve the desired result such as hardening or softening of a material. Heat treatment techniques include annealing, case hardening, precipitation strengthening, tempering, carburizing, normalizing, and quenching. Although the term heat treatment applies only to processes where the heating and cooling are done for the specific purpose of altering properties intentionally, heating and cooling often occur incidentally during other manufacturing processes such as hot forming or welding.

Vacuum melting

Vacuum induction melting (VIM) is a metal process that uses the principle of electromagnetic induction heating to smelt metal under vacuum conditions. During the electromagnetic induction process, eddy currents are generated, causing the metal to melt. This process can be used to refine high-purity metals and alloys.

Vacuum arc remelting (often abbreviated as VAR) is a process for producing metal ingots that are highly homogeneous in both mechanical and chemical properties. The vacuum arc remelting process can be used to refine special steels or materials required for harsh application environments such as biomedicine and aerospace.

 

Casting

Casting is a process in which metal is smelted into a liquid that meets certain requirements and poured into a mold. After cooling, solidification, and cleaning, casting with a predetermined shape, size, and performance is obtained. Because the casting blank is almost in shape, it eliminates the need for mechanical processing or a small amount of processing, reduces costs and reduces production time to a certain extent. Casting is one of the basic processes in the modern device manufacturing industry.

Metal Powder Injection Molding Technology (MIM) is a new powder metallurgy near-net-form molding technology formed by introducing modern plastic injection molding technology into the field of powder metallurgy.