Bearing is an important part of modern machinery equipment. Its main function is to support the mechanical rotating body, reduce its friction coefficient in the process of motion, and ensure its accuracy.

Bearing can be divided into rolling bearing and sliding bearing according to the different frictional nature of moving element. Among them, rolling bearing has been standardized and serialized, but compared with sliding bearing, its radial dimension, vibration and noise are larger, and its price is higher.

Rolling bearing generally consists of four parts: outer ring, inner ring, rolling body and holding frame. Strictly speaking, it consists of six parts: outer ring, inner ring, rolling body, holding frame, sealing and lubricating oil. Simply put, as long as the outer ring, inner ring and rolling body can be defined as rolling bearing. According to the shape of rolling body, rolling bearing can be divided into ball bearing and roller bearing.