Bearing is one of the indispensable basic components in mechanical engineering, which is widely used in various mechanical equipment. The accuracy of the bearing directly affects the performance and life of the equipment, so there are strict requirements for the tolerance level of the bearing. This paper will introduce bearing tolerance grade and its application in detail.

What is bearing tolerance?

Bearing tolerance refers to the maximum allowable deviation range of the bearing's inner and outer diameter, width and other dimensions during the manufacturing process. These tolerances determine the accuracy level of the bearing, which affects its performance in practical applications.

Common bearing tolerance levels

According to the international standard ISO 492 and the national standard GB/T 307.1-2018, the tolerance levels of bearings are mainly divided into the following:

Class P0 (Normal)

Radial runout of inner ring and outer ring: the maximum allowable deviation is larger.

Roundness error of raceway: ±0.015mm

Surface roughness of raceway: Ra ≤ 1.6μm

P0 is suitable for general use, usually used in agricultural machinery, construction machinery and other equipment with low precision requirements.

P6 class (Ordinary precision class)

Radial runout of inner and outer rings: improved from P0 stage.

Roundness error of raceway: ± 0.010mm

Surface roughness of raceway: Ra ≤ 1.25μm

Grade P6 is suitable for moderately demanding occasions, such as ordinary machine tool spindles, motors, etc.

P5 Class (Precision class)

Radial runout of inner and outer rings: further improvement.

Roundness error of raceway: ± 0.008mm

Surface roughness of raceway: Ra ≤ 0.8μm

P5 is suitable for high-precision mechanical equipment, such as high-precision machine tool spindles, high-speed rotating machinery, etc.

P4 level (Advanced Precision level)

Radial runout of inner and outer rings: very strict.

Roundness error of raceway: ± 0.005mm

Surface roughness of raceway: Ra ≤ 0.4μm

The P4 class is suitable for extremely demanding precision machinery, such as aerospace equipment, high-speed rotating machinery, etc.

Level P2 (Ultra precision)

Radial runout of inner and outer rings: extremely strict.

Roundness error of raceway: ± 0.003mm

Surface roughness of raceway: Ra ≤ 0.2μm

Class P2 is the highest tolerance class and is mainly used in special applications, such as high-precision instruments, optical equipment, etc.

How to choose the bearing tolerance level?

When selecting the bearing tolerance level, the following factors need to be considered:

1. Working conditions of the equipment: including speed, load, temperature, etc.

2. The accuracy requirements of the equipment: high-precision equipment needs to choose a higher level of bearings.

3. Economy: High-precision bearings cost more, need to find a balance between performance and cost.

4. Service life: High-precision bearings usually have a longer service life.

Precautions in practical application

1. Installation and maintenance: High-precision bearings have higher requirements for installation and maintenance, requiring professional operation.

2. Lubrication: bearings with different tolerance levels have different requirements for lubrication, and the appropriate lubricant needs to be selected.

3. Environmental conditions: high-precision bearings are more sensitive to environmental cleanliness and temperature changes.

conclusion

Bearing tolerance level is an important factor to determine its performance and application. When selecting and using bearings, tolerance levels must be reasonably selected according to the specific application needs and economic conditions to ensure the normal operation and long life of the equipment. By understanding the tolerance levels of bearings and their applications, we can better select and use bearings and improve the reliability and efficiency of mechanical equipment. I hope this article can provide you with valuable reference.