The key to bearing tolerance grade is to determine it according to the rotation accuracy of the shaft to the support point.

Level 0: It is generally used for bearing systems with a rotation accuracy of more than 10 microns, and is widely used. For example, the speed regulating mechanism on the ordinary CNC lathe, the tool feed mechanism, the speed regulating mechanism of the car, the speed regulating mechanism of the large tractor, and the rotary mechanism of ordinary chemical machinery such as motors, centrifugal pumps, and agricultural machinery.

Levels 6 and 5: in the precision bearing system with a rotation accuracy of 5-10 microns or higher speed, such as common bearings of CNC lathe (level 5 at the front support point and level 6 at the rear support point), more sophisticated instruments and equipment, instrument panel and its instruments, instrument panel and precision rotating mechanism.

Level 4 and Level 2: In super instruments, such as precision coordinate milling machines, transmission gear system software of precision grinding machines, such as instruments, instrument panels, and high-speed cameras, the rotation accuracy is not more than 5 microns, and the speed is relatively high. The former precision grade code of Chinese bearings.

The international standards are formulated in accordance with ISO standards, which are generally unified with ISO, and some are relatively strict.

Accuracy is divided into specification accuracy and rotation accuracy. It is divided into 0 degrees, 6X degrees, 6 degrees, 5 degrees, 4 degrees, and 2 degrees.

The previous bearing codes in China were: G (0), E (6), D (5), C (4), and B (2). The current standard code generally adopts German DIN specifications.

(a) P0 (0), P6 (6), P5 (5), P4 (4), P2 (2) (2). The general specification grade P0 is omitted from the bearing model and specification. Only the grade of P6 or above appears in the bearing model and specification.

For example, for 6205 and 6205/P5, the accuracy level of 6205 is P0, but it is omitted. In this way, we will introduce the image of P0 class bearings.

In addition, bearings of various accuracy are separated differently in the processing process, and their use values are also different. For example, the accuracy of HRB bearings in China is 1.5 times P6, 2 times P5, 2 times P4, 2 times P5, and 2.5 times P5.