How can I tell if a bearing can be used again?

To determine whether the bearing can be used again, it is necessary to consider the degree of bearing damage, machine performance, importance, operating conditions, inspection cycle, etc.

Regular maintenance, operation inspection, and replacement of peripheral parts are inspected to determine whether the bearings can be used again or whether they can be used better than bad.

First of all, it is necessary to carefully investigate and record the dismantled bearing and its appearance, and in order to find out and investigate the remaining amount of lubricant, the bearing should be cleaned well after sampling.

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

As a result of the inspection, if there is damage or abnormality in the bearing, the contents of the section on the injury will identify the cause and formulate countermeasures. In addition, if there are any of the following defects, the bearing can no longer be used, and a new bearing needs to be replaced.

a. Cracks and fragments in any of the inner and outer rings, rolling elements, and cages.

b. The inner and outer rings and rolling elements are peeled off.

c. The raceway surface, flange and rolling element are significantly jammed.

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

e. Rust and scarring of raceway surfaces and rolling elements.

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

g. Creep on the inner diameter of the inner ring or the outer diameter of the outer ring.

h. Severe discoloration due to overheating.

i. Severe damage to the sealing rings and dust caps of grease sealed bearings.

In-operation inspection and troubleshooting

The inspection items in operation include the rolling sound, vibration, temperature, lubrication status of the bearing, etc., and the details are as follows:

1.The rolling sound of a bearing

The sound meter is used to check the volume and sound quality of the rolling sound of the bearing in operation, and even if the bearing is slightly damaged such as peeling, it will emit abnormal and irregular sounds, which can be distinguished with the sound meter.

2. Vibration of the bearing

Bearing vibration is sensitive to bearing damage, such as spalling, indentation, rust, cracks, wear, etc., which are reflected in the bearing vibration measurement, so the vibration can be measured by using a special bearing vibration measuring device (frequency analyzer, etc.), and the specific situation of the abnormality cannot be inferred from the frequency division. The measured values vary depending on the conditions under which the bearings are used or where the sensors are mounted, so it is necessary to analyze and compare the measured values of each machine in advance to determine the judgment criteria.

3. The temperature of the bearing

The temperature of the bearing can be inferred from the temperature outside the bearing chamber, and if the temperature of the outer ring of the bearing can be directly measured by using the oil hole, it is more appropriate. In general, the temperature of the bearing starts to rise slowly with the operation, reaching a stable state after 1-2 hours. The normal temperature of the bearing varies depending on the heat capacity, heat dissipation, speed and load of the machine. If the lubrication and mounting parts are suitable, the temperature of the bearing will rise sharply, and an abnormally high temperature will occur, so it is necessary to stop the operation and take the necessary precautions. The use of thermal inductors can monitor the working temperature of the bearing at any time, and realize the automatic alarm or stop when the temperature exceeds the specified value to prevent the occurrence of combustion shaft accidents.

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