The key to the bearing tolerance level is to determine the rotation accuracy of the shaft to the support point.
Level 0: Generally used for bearing systems with a rotational accuracy of more than 10 microns, and the application is very common. For example, the speed control mechanism of ordinary CNC lathes, the knife moving mechanism, the speed control mechanism of the car, the speed control mechanism of the large tractor, the rotating mechanism of ordinary chemical machinery such as motors, centrifugal pumps and agricultural machinery.
Level 6, Level 5: In the precision bearing system with the rotational accuracy of 5-10 microns or high rotational speed, such as the commonly used bearings of CNC lathes (the front support point is level 5, the rear support point is level 6), finer equipment, instruments Panels and their gauges, instrument panels and precision rotary mechanisms.
Level 4, Level 2: In super instrument, such as precision coordinate milling machine, transmission gear system software of precision grinding machine, such as instrumentation, instrument panel and high-speed camera, etc., the rotation accuracy does not exceed 5 microns, and the speed is relatively high. The old code precision grade code before the Chinese bearing.
The norms formulated internationally are all formulated in accordance with ISO standards, which are generally unified with ISO, and some are relatively strict.
Accuracy is divided into specification accuracy and rotational accuracy. Divided into 0 degrees, 6X degrees, 6 degrees, 5 degrees, 4 degrees, 2 degrees.
The previous bearing code regulations in China are: Grade G (0), Grade E (6), Grade D (5), Grade C (4), Grade B (2). The current standard code generally adopts the German DIN standard.
(a) P0(0), P6(6), P5(5), P4(4), P2(2) level(2). Ordinary specification grade P0, which is reflected in the bearing model specification, is omitted. Only the grade of P6 or above, the grade code appears in the bearing model specification.
For example: 6205 and 6205/P5, where the accuracy level of 6205 is P0, just omitted. In this way, I will introduce to you that the P0 grade is the image of the non-accuracy grade bearing.
In addition, bearings of various precisions are separated differently during processing and have different use values. For example: the use value of HRB bearings in China, the accuracy is 1.5 times that of P6, 2 times that of P5, 2 times that of P4, 2 times that of P5, and 2.5 times that of P5.