Precision spindle bearings are divided into P0-P5, and the grades are gradually increased. Among them, P0 is the general precision, and the other grades are all high-precision grades. Naturally, different grade classification standards and different types of rolling bearings have different grade classification methods, but the actual meaning is the same. The performance index of the precision spindle bearing stipulates that the rotating body has high runout accuracy, high-speed operation, and the specified friction and friction change are small. Precision spindle bearings and general rolling bearings need to be distinguished from the following aspects: 1. The specified specifications are different, and the specification errors (inner diameter, diameter, ellipse, etc.) of products with high precision grades are smaller than those of bearings with low precision grades ; 2. The specified values ​​of rotation accuracy are different, and the rotation accuracy of products with high accuracy grades is more stringent than the specified values ​​of bearings with lower accuracy grades; 3. The specified values ​​of appearance shape and appearance quality are different, and the specified values ​​of appearance shape and appearance quality are different. The appearance shape and appearance quality of the product (the appearance surface roughness of the raceway and the raceway, the circular deviation and the groove shape error, etc.) are stricter than the values ​​specified for the products with low accuracy grades; 4. The products with particularly high accuracy grades are The raw material is more favorable than the raw material characteristics of the general precision grade product.