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

Level 0: it is generally used for bearing systems with rotation accuracy over 10 microns, and its application is very common. For example, the speed regulating mechanism of the ordinary CNC lathe, the tool feeding mechanism, the speed regulating mechanism of the car, the speed regulating mechanism of the large tractor, and the rotating mechanism of the ordinary chemical machinery such as the motor, the centrifugal pump and the agricultural machinery.

Level 6, level 5: in precision bearing system with rotation accuracy of 5-10 microns or higher speed, such as common bearings of CNC lathe (front support point level 5, rear support point level 6), 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 fine coordinate milling machine, transmission gear system software of fine grinding machine, such as instruments, instrument panel and high-speed camera, the rotation accuracy does not exceed 5 microns, and the rotation speed is relatively high. The old code of Chinese bearing precision grade code.

International standards are formulated in accordance with ISO standards, which are generally unified with ISO, and some of them are relatively strict.

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

In China, the previous bearing codes were: grade g (0), Grade E (6), grade D (5), grade C (4), grade B (2). The current standard code generally adopts German DIN specification.

(a) P 0 (0), P 6 (6), p 5 (5), P 4 (4), P 2 (2). Ordinary specification grade P0, reflected in the bearing model specification is omitted, only P6 or P6 above grade, grade code appears in the bearing model specification.

For example: 6205 and 6205 / P5, of which the accuracy level of 6205 is P0, but it is omitted. In this way, I will introduce the image of bearing of grade P0 right and wrong accuracy.

In addition, various precision bearings in the process of processing separation is different, in the use value is also different. For example, the accuracy of HRB bearing in China is 1.5 times of P6, 2 times of P5, 2 times of P4, 2 times of P5 and 2.5 times of P5.