Roller bearings are generally composed of four parts: inner ring, outer ring, rolling element and cage. The inner ring cooperates with the shaft and rotates together, the outer ring plays a supporting role, and the rolling element is evenly distributed between the inner ring and the outer ring through the cage to reduce friction loss. Roller bearings are an important mechanical part, mainly used to support mechanical rotating bodies, reduce the friction coefficient during movement, and ensure rotation accuracy. Roller bearings are usually sealed structures, filled with grease, provide long-term effective lubrication, and users can be free from lubrication and maintenance.