Powder metallurgy is a process technology for preparing metal or using metal powder (or a mixture of metal powder and non-metal powder) as raw materials, forming and sintering, to produce metal materials, composite materials and various types of products. The powder metallurgy products industry in a broad sense includes iron and stone tools, cemented carbide, magnetic materials and powder metallurgy products. The powder metallurgy products industry in the narrow sense only refers to powder metallurgy products, including powder metallurgy parts (accounting for the majority), oil-bearing bearings and metal injection molding products.
What exactly is "Powder Metallurgy", you will understand after reading this!
Process characteristics
1. The density of products is controllable, such as porous materials, high-density materials, etc.;
2. Fine grains, uniform microstructure, and no segregation of components;
3. Near-shape forming, raw material utilization rate> 95%;
4. There is little and no cutting, and the cutting process is only 40~50%;
5. The material components are controllable, which is conducive to the preparation of composite materials;
6. Preparation of insoluble metals, ceramic materials and nuclear materials.
Basic process flow
1. Flour milling
Pulverizing is the process of making raw materials into powder. Commonly used methods of making powder include oxide reduction method and mechanical method.
2. Mixing
Mixing is the process of mixing various required powders in a certain proportion and homogenizing them to make the green powder. There are three types: dry type, semi-dry type and wet type, which are used for different requirements.
3. Forming
Forming is the process of putting a uniformly mixed mixture into a press mold and pressing it into a parison with a certain shape, size and density. The molding method is basically divided into pressure molding and pressureless molding. Compression molding is most widely used in compression molding.
4. Sintering
Sintering is a key process in the powder metallurgy process. The formed compact is sintered to obtain the required final physical and mechanical properties. Sintering is divided into unit system sintering and multi-system sintering. In addition to ordinary sintering, there are also special sintering processes such as loose sintering, immersion method, and hot pressing method.
5. Post-processing
The treatment after sintering can adopt various methods according to different product requirements. Such as finishing, oil immersion, machining, heat treatment and electroplating. In addition, in recent years, some new processes such as rolling and forging have also been applied to the processing of powder metallurgy materials after sintering, and have achieved ideal results.
main application
The application range of powder metallurgy products is very wide, from ordinary machinery manufacturing to precision instruments; from hardware tools to large-scale machinery; from electronics industry to motor manufacturing; from civil industry to military industry; from general technology to cutting-edge high technology, you can see The figure of powder metallurgy process.
>>>>Typical Application-Automotive Industry
A large number of powder metallurgy parts are used in automobiles
1. Engine parts
In order to improve fuel economy and control emissions, the working conditions of automobile engines have become more severe. The use of powder metallurgy valve seats, valve guides, VCTs and sprockets, etc., can have high strength, high wear resistance and excellent heat resistance.
Intake and exhaust valve seat
2. Transmission parts
Combining the nearly-formed synchronizer ring gear with dual friction materials and high-strength materials, the world's first clutch hub is made. In addition, through high-temperature sintering, high-strength parts such as handle shift gears and shift forks are manufactured.
The main components of powder metallurgy transmission in automobiles include: synchronizer hub, synchronizer ring, parking components, column shift components and control levers, etc.
3. Shock absorber parts
In the shock absorbers of automobiles and motorcycles, piston rods and piston guide valves are all important parts. Taking into account the stable damping force of the shock absorber, the use of powder metallurgy parts with a high-precision sheet surface can reduce friction, ensure the stability of handling, and improve ride comfort.
Shock absorber parts
A video briefly introduces the whole process of traditional powder metallurgy, from car material to powder, then pressing and sintering, and finally becoming car parts, made by GKN.
>>>>Typical Application-Aerospace Industry
Among the powder metallurgy materials used in the aviation industry are special functional materials, such as friction materials, antifriction materials, sealing materials, filter materials, etc., which are mainly used for aircraft and engine auxiliaries, instruments, and airborne equipment. The other type is high-temperature and high-strength structural materials, which are mainly used for important structural parts of aircraft engine mainframes.
Aviation brake pair-BY2-1587
Aviation filter
>>>>Typical Application-Household Appliances
Some household appliances materials and parts can only be manufactured by powder metallurgy, such as porous self-lubricating bearings in refrigerators, compressors, washing machines, electric fans, etc.; some household appliances materials and parts are manufactured by powder metallurgy with better quality and lower prices , Such as complex-shaped gears and magnets in household air-conditioning exhaust fans and vacuum cleaners.