To determine whether a bearing can be reused, it is necessary to consider the degree of bearing damage, machine performance, importance, operating conditions, inspection cycles, and other factors before making a decision.
Regular maintenance, operation inspection, and inspection of bearings removed during peripheral component replacement of equipment to determine whether they can be reused or whether their condition is better or worse.
Firstly, it is necessary to carefully investigate and record the removed bearings and their appearance. In order to determine and investigate the remaining amount of lubricant, after sampling, the bearings should be cleaned thoroughly.
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 a bearing can be reused, it is necessary to consider the degree of bearing damage, machine performance, importance, operating conditions, inspection cycles, and other factors before making a decision.
If damage or abnormal conditions are found in the bearings during the inspection, the cause should be identified in the section on damage and countermeasures should be 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, and retaining frames has cracks or fragments.
b. Either the inner or outer circle or the rolling element is peeled off.
c. The rolling surface, blocking edge, and rolling element have significant jamming damage.
d. The retainer is severely worn or the rivets are loose.
e. Rust and scratches on the raceway surface and rolling elements.
f. There are significant indentations and marks on the rolling surface and rolling elements.
g. There is creep on the inner diameter surface of the inner ring or the outer diameter of the outer ring.
h. Overheating causes 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 bearing rolling sound, vibration, temperature, lubrication status, etc. The specific situation is as follows:
Rolling sound of a bearing
Using a sound detector to check the size and sound quality of the rolling sound of the running bearings. Even if there is slight peeling or damage to the bearings, abnormal and irregular sounds will be emitted, which can be distinguished by the sound detector.
Vibration of two bearings
Bearing vibration is very sensitive to bearing damage, such as peeling, indentation, rust, cracks, wear, etc., which will be reflected in bearing vibration measurement. Therefore, by using special bearing vibration measuring instruments (frequency analyzers, etc.), the magnitude of vibration can be measured, and the specific situation of abnormalities cannot be inferred through frequency differentiation. The measured values may 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 outer ring temperature of the bearing can be directly measured using oil holes, it is more appropriate. Usually, the temperature of the bearing gradually increases with the start of operation and reaches a stable state after 1-2 hours. The normal temperature of bearings varies depending on the machine's heat capacity, heat dissipation, speed, and load. If the lubrication and installation parts are suitable, the bearing temperature will rise sharply, resulting in abnormal high temperatures. At this time, the operation must be stopped and necessary preventive measures must be taken. By using a thermal sensor, the working temperature of the bearing can be monitored at any time, and an automatic alarm or stop can be triggered when the temperature exceeds the specified value to prevent shaft accidents from occurring.