Causes of damage to rolling bearings

Common faults of rolling bearings

There are generally two types of failure phenomena of rolling bearings. One is that the temperature of the bearing installation part is too high.

Second, there is noise during bearing operation.

 1. Bearing temperature is too high. When the mechanism is running, the part where the bearing is installed is allowed to have a certain temperature. When touching the housing of the mechanism with your hand, it is normal to not feel hot, otherwise it indicates that the bearing temperature is too high. The reasons for the excessively high bearing temperature include: the quality of lubricating oil does not meet the requirements or deterioration, the viscosity of lubricating oil is too high; the mechanism assembly is too tight (insufficient clearance); the bearing assembly is too tight; the bearing race rotates on the shaft or in the housing; Large; the bearing cage or rolling elements are broken, etc.

 2. Bearing noise. Rolling bearings are allowed to have a slight running noise during operation. If the noise is too loud or there is abnormal noise or impact, it indicates that the bearing is faulty. The causes of noise produced by rolling bearings are more complicated. One is the wear of the mating surfaces of the inner and outer rings of the bearing. Due to this kind of wear, the matching relationship between the bearing and the housing, and the bearing and the shaft is destroyed, causing the axis to deviate from the correct position, causing abnormal noise when the shaft is moving at high speed. When the bearing is fatigued, the metal on its surface will peel off, which will also increase the radial clearance of the bearing and produce abnormal noise. In addition, insufficient bearing lubrication, formation of dry friction, and bearing breakage will cause abnormal noise. After the bearing is worn and loosened, the cage is loose and damaged, and abnormal noise will also be produced.

Third, the damage of the rolling bearing When the rolling bearing is disassembled and inspected, the fault and the cause of the damage can be judged according to the damage of the bearing.

1. Metal peeling off the surface of the raceway The rolling elements of the bearing and the raceway surfaces of the inner and outer rings are subjected to periodic pulsating loads, resulting in periodic contact stress. When the number of stress cycles reaches a certain value, fatigue spalling occurs on the working surfaces of the rolling elements or inner and outer ring raceways. If the bearing load is too large, this fatigue will increase. In addition, if the bearing is installed incorrectly and the shaft is bent, the raceway will peel off. Fatigue spalling of the bearing raceway will reduce the running accuracy of the shaft and cause vibration and noise to the mechanism.

2. Bearing burns Burnt bearings have tempered colors on raceways and rolling elements. The causes of burns are generally insufficient lubrication, the quality of the lubricating oil does not meet the requirements or deterioration, and the bearing assembly is too tight.

3. Plastic deformation Uneven dents appear on the contact surface between the raceway and the roller of the bearing, indicating that the bearing is plastically deformed. The reason is that the local stress on the working surface of the bearing exceeds the yield limit of the material under the action of a large static load or impact load. This situation generally occurs on a bearing that rotates at a low speed.

 4. Cracks in the bearing races The causes of cracks in the bearing races may be that the bearing is too tightly fitted, the outer part of the bearing or the inner ring is loose, the bearing housing is deformed, and the surface where the bearing is installed is poorly processed.

5. The cage is broken. The reason is insufficient lubrication, broken rolling elements, skewed seat ring and so on.

 6. The metal of the cage adheres to the rolling elements. The possible cause is that the rolling elements are stuck in the cage or insufficient lubrication.

7. The raceway of the seat ring is severely worn. It may be caused by foreign matter falling into the seat ring, insufficient lubricating oil or improper lubricating oil grade.