Accuracy and grade of bearing:
The accuracy of rolling bearings is divided into (mainly) dimensional accuracy and rotational accuracy. The accuracy level has been standardized and divided into six levels: 0, 6X, 6, 5, 4, and 2.
The accuracy increases sequentially from grade 0. For general use, grade 0 is sufficient, but when used in the conditions or occasions shown in Table 1, grade 5 or higher is required.
The above-mentioned accuracy grades are based on ISO standards, but their names differ from country to country.
Dimensional Accuracy (Items Related to Shaft and Housing Mounting)
1. Allowable deviation of inner diameter, outer diameter, width and assembly width
2. The allowable deviation of the inner and outer circle diameters of the roller group
3. The allowable limit value of chamfer size
4. Allowable variation of width
Rotation accuracy (item related to the runout of the rotating body)
1. Allowable radial runout and axial runout of inner ring and outer ring
2. Allowable lateral runout of the inner ring
3. The allowable variation of the inclination of the outer diameter surface
4. The allowable variation of the thickness of the thrust bearing raceway
5. The allowable deviation and allowable variation of the tapered hole.