Powder metallurgy bearings are made of metal powder and other anti-friction material powders by pressing, sintering, shaping and oil immersion. They have a porous structure. After soaking in hot oil, the pores are filled with lubricating oil. The suction effect of the rotation and the heating of friction cause the metal and the oil to be heated and expand, and the oil is squeezed out of the pores, and then the friction surface plays a lubricating role. After the bearing cools, the oil is sucked back into the pores.

Powder metallurgy oil-impregnated bearings (oil-impregnated bearings) are a kind of porous alloy products impregnated with lubricating oil in the pores. When the shaft rotates, the temperature of the oil-impregnated bearing increases due to the friction between the shaft and the oil-impregnated bearing and the pumping effect. Lubricating oil permeates the friction surface that permeates the inner or outer diameter of the oil-impregnated bearing when the shaft stops rotating. The lubricating oil is returned to the inside of the oil-impregnated bearing. Therefore, the consumption of lubricating oil is very small, and it can be used for a long time without supplying lubricating oil from the outside. It is very suitable for occasions where oil supply is difficult and lubricating oil pollution is avoided.

A large number of oil-impregnated bearings are used in: motor industry, automobile and motorcycle industry, home appliance industry, digital products, office equipment, power tools, textile machinery, packaging machinery and other mechanical equipment.

Powder metallurgy oil-impregnated bearings are generally made of raw material powder through pressing, sintering, shaping, and oil immersion. Most of today's machines are highly automated. The daily output is relatively large, and most products can be formed at one time, so the larger the batch, the better the production. And if the molds used now are a little less, it may be hundreds of thousands, and if there are more molds, it may be more than a million. However, the cost of the mold is relatively high, so if the batch is small, it is not easy to do, and the time to replace the mold is also long.

Generally speaking, powder metallurgy oil-impregnated bearings can be formed at one time, basically without cutting. The cost is lighter than machining, and there is less material waste, so the price is cheaper. It is also in line with the current national policy of promoting energy conservation, so it is considered a technology that will not be outdated.