What is an oil-free bearing?

In order to ensure the smooth and reliable operation of the bearings, most of the bearings are lubricated for lubrication, in order to reduce the internal friction and wear of the bearings, to prevent sticking: to prolong the fatigue life of the bearings; to discharge frictional heat, or heat from the outside. At the same time, the oil film also has a certain vibration absorption capacity. However, the biggest disadvantage of adding lubricating oil is that it requires good sealing performance, otherwise it will cause leakage, and some have special requirements. The equipment does not allow leakage of lubricating oil. Therefore, people use other lubricating materials instead of lubricating oil to invent. Oil-free bearings make it not only have the advantages of lubricating bearings, but also prevent environmental pollution caused by leakage.

Oil-free bearings mainly include gas lubricated bearings, composite lubricated bearings, and water lubricated bearings.

Gas lubrication bearings:

Gas lubricated bearings are plain bearings that use gas as a lubricant. The most commonly used gas lubricant is air, and nitrogen, argon, hydrogen, helium, etc. may also be used as needed. Gas-lubricated bearings form the same mechanism as liquid-lubricated bearings. Gas lubricated bearings utilize gas transportability, diffusivity, viscosity and thermal conductivity, adsorption and compressibility. Under the action of fluid dynamic pressure effect, static pressure effect and extrusion effect, a complete gas film is formed between the friction pairs, which has the functions of supporting load and reducing friction.

Gas lubricated bearings are generally classified into three types: gas dynamic pressure bearings, gas static pressure bearings and gas extrusion bearings. The lubrication state of the actual bearing often exists in the form of dynamic and static pressure, dynamic, extrusion, static, extrusion and dynamic, static and extrusion lubrication. Gas-lubricated bearings form the same mechanism as liquid-lubricated bearings.

Composite lubricated bearing:

Due to the requirements of special production processes, some key equipment of industrial and mining enterprises operate under extremely harsh conditions. Due to the heavy equipment and high ambient temperature, the dust is large or the air contains acidic corrosive gases. There are many problems in the lubrication of the equipment, and the friction and wear are serious. At present, most of the oil and grease lubrication are still used. In fact, these industrial and mining conditions have exceeded the range of oil and grease lubrication. Very easy to bite or bite the bearing and other friction pairs. Causes severe wear and damage of parts, often causing equipment to be out of service.


The composite material used in composite lubricated bearings is a new type of extreme pressure resistant solid lubricant consisting of a metal substrate and a solid lubricant paste embedded in the holes or slots of the substrate. The metal substrate takes up most of the load during the rubbing process. After friction, the solid lubricant in the hole or the groove is transferred or reversely transferred to the friction surface, and a solid transfer film which is well lubricated, firmly adhered and uniformly covered is formed on the friction surface, and friction and wear are greatly reduced. As the friction progresses, the embedded solid lubricant is continuously supplied to the friction surface, ensuring good lubrication of the friction pair during long-term operation.

Water lubricated bearing:

Since the oil resource crisis in the 1970s and the emphasis on environmental protection in recent years, hydraulic transmission technology is facing severe challenges, and water-lubricated bearings are gradually being promoted and applied. Water-lubricated bearings use water as a lubricant and working medium, which not only saves a lot of oil, but also avoids the environmental pollution of traditional bearings with oil as a lubricating medium. At the same time, water has the advantages of no pollution, wide source, safety and flame retardancy, and is an ideal lubricating medium. Moreover, it can also reduce the key problems of friction, wear, vibration, noise, and non-functional consumption of the friction pair. Therefore, the research of water-lubricated bearings has important theoretical research and application value for improving mechanical efficiency and protecting the environment, and has become a hot spot of concern to all countries.


Reprinted from the network