How to determine if the bearing can be reused?

To determine whether bearings can be reused, it is necessary to consider the degree of bearing damage, machine performance, importance, operating conditions, inspection cycle, etc. before making a decision.




Conduct regular maintenance, operation inspection, and inspection of bearings that have been disassembled during the replacement of peripheral parts of the equipment to determine whether they can be reused or whether the condition is good or bad.




Firstly, it is necessary to carefully investigate and record the dismantled bearings and their appearance. In order to clarify and investigate the remaining amount of lubricant, after sampling, the bearings should be thoroughly cleaned.




Secondly, check the condition of the raceway surface, rolling surface, and mating surface, as well as the wear status of the cage, for any damage or abnormalities.   




To determine whether bearings can be reused, it is necessary to consider the degree of bearing damage, machine performance, importance, operating conditions, inspection cycle, etc. before making a decision.




According to the inspection results, if any damage or abnormalities are found in the bearings, the cause of the damage section should be identified and countermeasures formulated. In addition, according to the inspection results, if there are any of the following defects, the bearing cannot be used anymore and needs to be replaced with a new one.




a. Any one of the inner and outer rings, rolling elements, or cages has cracks or fragments.



b. Any one of the inner and outer rings or rolling elements has detachment.



c. The raceway surface, edge guards, and rolling elements are significantly damaged.



d. The cage is severely worn or the rivets are loose.



e. Rust and scratches on the raceway surface and rolling body.



f. There are significant indentations and scratches on the rolling surface and rolling body.



g. There is creep on the inner diameter surface of the inner ring or the outer diameter of the outer ring.



h. Overheating can cause severe discoloration.



i. The sealing ring and dust cover of the grease sealed bearing are severely damaged.




Inspection and troubleshooting during operation




The inspection items during operation include the rolling sound, vibration, temperature, lubrication status, etc. of the bearings, and the specific situation is as follows:




The rolling sound of a bearing




Use a sound detector to check the size and sound quality of the rolling sound of the running bearing. Even if there is slight peeling or other damage to the bearing, abnormal and irregular sounds will be emitted, which can be distinguished using a sound detector.




Vibration of two bearings




Bearing vibration is very sensitive to bearing damage, such as peeling, indentation, rust, cracks, wear, etc., which can be reflected in bearing vibration measurement. Therefore, the size of vibration can be measured by using special bearing vibration measuring devices (frequency analyzers, etc.), and the specific abnormal situation cannot be inferred through frequency analysis. The measured values vary depending on the usage conditions of the bearings or the installation position of the sensors, so it is necessary to analyze and compare the measured values of each machine in advance to determine the judgment criteria.




Temperature of three bearings




The temperature of the bearing can generally be inferred from the temperature outside the bearing chamber. If the temperature of the bearing outer ring can be directly measured using an oil hole, it is more suitable. Usually, the temperature of the bearing gradually increases with operation and reaches a stable state after 1-2 hours. The normal temperature of bearings varies depending on the heat capacity, heat dissipation, rotational speed, and load of the machine. If the lubrication and installation parts are suitable, the bearing temperature will suddenly rise and abnormal high temperatures will occur. At this time, the operation must be stopped and necessary preventive measures must be taken. The use of a thermal sensor can monitor the working temperature of the bearing at any time, and achieve automatic alarm or stop to prevent shaft accidents when the temperature exceeds the specified value.