Bearing selection-How to choose the right bearings?

The bearing type is typically selected by technical personnel based on the operational conditions and bearing load requirements of the supporting products. Improper bearing type selection may result in failure to achieve the designed service life or excessive performance waste.

Bearing type selection

The bearing type is typically selected by technical personnel based on the operational conditions and bearing load requirements of the supporting products. Improper bearing type selection may result in failure to achieve the designed service life or excessive performance waste.

Bearing clearance selection

Bearing clearance selection directly related to the operational conditions, bearing load, rotation speed, temperature, fit tolerance, etc. After assembly, the bearing clearance is reduced due to t interference fits between the bearing bore and shaft, as well as the outer ring and housing. The clearance reduction is calculated as interference fit value*60% (for thin-walled series such as 6700, 6800, 6900 series, this value can reach 70% or even higher). For example, if the clearance before assembly is 0.01mm and the interference fit during assembly is 0.01mm, the bearing clearance after assembly becomes 0.004mm. In theory, the noise and service life of the bearing reach the best state at zero clearance, but in actual operation, considering issues such as temperature rise, the bearing clearance after assembly is better to be 0.002mm-0.005mm.

The standard clearance group of rolling bearings is divided into C1,

C2, CM, C0, C3, C4, C5 C1＜C2 clearance C2＜Conventional Clearance

CM motor bearing specific clearance belongs to C0 lower limit part C0 conventional clearance (generally not marked)

C3 > Normal clearance C4 > C3 clearance C5 > C4 clearance;

Bearing grease selection

Proper lubrication is essential for the reliable bearing performance. A significant amount of data proves that over 40% of bearing failures are caused by poor lubrication. Therefore, grease selection must align with bearing operating parameters, including rotational speed, load, temperature, noise requirements, and starting torque. The grease’s properties (e.g., viscosity, thermal stability) should be matched to these conditions.

Bearing sealing types selection

Bearings can be lubricated with oil or grease. Open-type bearings typically use oil lubrication , while those with dust cover or rubber seals usually use grease lubrication. Dust covers are suitable for high

temperature environments or areas with favorable conditions. Rubber seals come in two types: contact seals and non-contact seals. Contact seals offer excellent dust resistance but have higher starting torque, whereas non-contact seals have lower starting torque but inferior sealing performance compared to contact seals. The appropriate sealing type can be selected based on actual operating conditions.