Powder metallurgy bearings are made of metal powder and other friction-reducing materials by powder compaction, sintering, shaping and oil immersion. They have porous structure. After soaking in hot oil, the pore space is filled with lubricating oil. When working, due to the suction effect of journal rotation and friction heating, the metal and oil are heated and expanded, the oil is extruded from the pore space, and then the friction surface plays a lubricating role. After cooling, the oil of the bearings is filled with lubricating oil. It is sucked back into the pore.

Powder metallurgy oil bearing (oil bearing) is a kind of porous alloy products with lubricating oil in the pore. When the shaft rotates, the friction between the shaft and the oil bearing increases the temperature of the oil bearing and pumps the oil bearing. The lubricating oil seeps out of the friction surface which seeps out of the inner or outer diameter of the oil bearing when the shaft stops rotating. The lubricating oil is refluxed into the oil bearing. Therefore, the consumption of lubricating oil is very small, and it can be used for a long time without supplying lubricating oil from outside. It is very suitable for the occasion of difficult oil supply and avoiding lubricating oil pollution.

Oily bearings are widely used in motor industry, automobile and motorcycle industry, household appliances industry, digital products, office equipment, electric tools, textile machinery, packaging machinery and other mechanical equipment.

Powder metallurgy oil bearing is generally made of raw material powder by pressing, sintering, shaping, oil immersion and other processes. Most of today's machines are highly automated. Daily production is relatively large, most products can be formed at one time, so the larger the batch, the better the production. Moreover, if we use fewer moulds now, we can make hundreds of thousands of moulds, and if we use more moulds, we can make more than one million moulds. But the cost of the mould is relatively high, so if the batch is small, it is not easy to do, and the time to replace the mould is also long.

Powder metallurgy oil bearing can be formed at one time, basically without cutting. The cost is lighter than that of machine processing, and the material waste is less, so the price is cheaper. It is also in line with the current national policy of energy conservation, so it is considered to be a technology that will not fall behind.

Powder metallurgy oil bearing has been filled with lubricating oil in its matrix by vacuum immersion method. Because of temperature rise and pump suction, the lubricating oil will seep into the operating surface, so it can be used in situations without additional lubricating oil.