Phenomenon 1: Metal peeling off the raceway surface
Cause:
1. The bearing rolling elements and the raceway surfaces of the inner and outer rings are subject to periodic pulsating loads, resulting in periodically changing contact stress. When the stress reaches a certain value, fatigue shedding will occur on the rolling elements and raceway surfaces;
2. The bearing load is too large, which aggravates fatigue;
3. If the bearing is installed incorrectly and the shaft is bent, the raceway will peel off;
4. Fatigue spalling of the bearing raceway will reduce the operating accuracy of the shaft and cause vibration and noise in the mechanism.
Solution:
1. Install the bearing correctly;
2. Reduce the bearing load (or replace the bearings that meet the operating load);
3. Clean bearing parts regularly and use clean grease;

4. Replace the bearings.

Phenomenon 2: Bearing burns (observe the bearing rolling elements and whether there is tempering color on the raceway, you can know whether the bearing is burned)
Cause:
1. Insufficient lubrication;
2. The quality of lubricating oil does not meet the requirements or deteriorates;
3. The bearing assembly is too tight.

Solution: Replace the bearings.

Phenomenon 3: Plastic deformation of the bearing (uneven pits appear on the contact surface between the rolling elements of the bearing and the raceway, which indicates that the bearing has plastic deformation)
Cause: Under a large static load or impact load, the local stress on the working surface of the bearing exceeds the yield limit of the material. This situation generally occurs in bearings rotating at low speeds.
Solution: Replace the bearings.