The main purpose of bearing lubrication is to prevent direct contact between bearing rings, rolling elements and cages through the formation of an oil film, thereby reducing friction and wear on the bearing contact area. The main functions of lubrication are: 1. Reduce friction and wear between bearing rings, rolling elements and cages. 2. Extend the fatigue life of the bearing, the rolling fatigue life of the bearing depends on the viscosity of the oil between the contact surfaces and the thickness of the oil film formed. 3. The use of circulating lubrication can also discharge frictional heat and heat from the outside to prevent overheating of the bearing and deterioration of the oil. 4. Proper lubrication helps prevent foreign matter from entering the bearing and preventing rust. Lubrication methods and lubricants In general, there are two types of lubrication methods: oil lubrication and grease lubrication: Oil lubrication: 1. Suitable for high-speed running bearings. 2. Oil lubrication is a good method of lubrication when the bearing and lubricating element are installed in the same frame. 3. Suitable for high temperature working environment. 4. Oil is a good lubricant for use with centralized oil supply systems as auxiliary mechanical components. 5. Where there is a requirement for bearing friction torque, oil is a good lubrication method. Grease lubrication: 1. Easily held in bearings without elaborate attachments. 2. It can be used for a long time without replacement. 3. It can effectively isolate the dirt from entering the bearing. 4. Closed bearings are filled with grease at the factory. The filling amount of grease is generally 30%-60% of the effective space in the bearing. Excessive filling of grease may cause heat generation and grease leakage.