1. Bearing model selection

Bearing models are generally chosen by the user’s technical personnel based on the operating conditions of the auxiliary equipment and the load they will carry. Sales staff mainly need to understand whether the bearing selected by the user can withstand the actual load. If it does not meet the application requirements, the customer should be advised to change the model as soon as possible. However, for special products, there is usually no problem with the model selection.

2. Bearing internal clearance selection

When customers purchase bearings, they usually only specify the model and brand, and rarely mention requirements for internal clearance. Sales personnel should ask about the bearing’s operating conditions – especially rotational speed, temperature, and fit tolerances, which are directly related to clearance selection. Generally, most motors running at speeds below 3500 rpm use standard clearance (e.g., CN clearance). High-temperature and high-speed motors require relatively larger clearance.

Interference fit effect: After assembly, the bearing internal clearance will be reduced due to interference fit on the inner ring (bore expansion) and outer ring (contraction).
Reduction in clearance ≈ interference fit × 60% (except for aluminum housing bearings).

Example: If the bearing clearance before assembly is 0.01 mm and the interference fit during assembly is 0.01 mm, then the clearance after assembly becomes 0.004 mm.
Theoretically, noise level and service life reach their best at zero clearance. However, in actual operation, considering temperature rise and other factors, the post‑assembly clearance of 0.002 mm to 0.004 mm is optimal.

3. Grease selection

Grease selection is generally based on bearing rotational speed, heat resistance, noise level requirements, starting torque, etc. This requires sales and technical staff to have a good understanding of the characteristics of different greases.

4. Bearing seal type selection

Bearing lubrication can be divided into oil lubrication and grease lubrication. Oil‑lubricated bearings are commonly used in bearing supports, while grease‑lubricated bearings are usually sealed with dust covers or rubber seals.

• Dust cover – suitable for high‑temperature applications or clean operating environments.

• Rubber seals – divided into contact seals and non‑contact seals. Contact seals provide excellent dust protection but have higher starting torque. Non‑contact seals have lower starting torque but do not seal as effectively as contact seals.

2026-05-09