We inspect the bearings that are dismantled during regular maintenance, operation inspection and replacement of peripheral parts of the equipment to determine whether they can be used again or whether they are in good or bad condition.

First of all, the dismantled bearings and their appearance should be carefully investigated and recorded, and the bearings should be well cleaned after sampling in order to find out and investigate the remaining amount of lubricant.

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

To determine whether the bearings can be used again, it is necessary to consider the degree of damage to the bearings, the performance of the machine, the importance of the operating conditions, the inspection cycle, and so on, and then decide.

As a result of the inspection, if the bearing is found to be damaged or in an abnormal condition, identify the cause and formulate countermeasures as described in the section on injuries. In addition, inspection results, if there are the following kinds of defects, the bearing can not be used again, need to replace the new bearing.

a. Any of the inner and outer rings, rolling elements, and cages are cracked or splintered. 

b. Inner and outer rings, rolling elements, any one of which has peeling. 

c. The raceway surface, retaining edge, rolling body has significant jamming. 

d. Cage wear is serious or rivets are loose. 

e. The raceway surface and rolling body are rusted and scarred. 

f. Rolling surface, rolling body with significant indentation and scoring. 

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

h. Overheating and discoloration. 

i. Seals and dust caps of grease sealed bearings are seriously damaged. 

Inspection and troubleshooting during operation

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

A bearing rolling sound

The size and quality of the rolling sound of the bearings in operation are checked by means of a stylus. Even if the bearings are slightly damaged, such as peeling, they will emit abnormal and irregular sounds, which can be distinguished by means of a stylus. 

Bearing vibration

Bearing vibration is very sensitive to bearing damage, such as spalling, indentation, corrosion, cracks, abrasion, etc. will be reflected in the bearing vibration measurement, so by using a special bearing vibration measuring device (frequency analyzer, etc.) can be measured by the size of the vibration, through the frequency of the score can not be deduced from the specifics of the abnormality. The measured value varies depending on the conditions of use of the bearing or the location of the sensor installation, etc., so it is necessary to analyze and compare the measured value of each machine beforehand to determine the judgment criteria. 

Bearing temperature

Bearing temperature, generally have the temperature outside the bearing chamber can be inferred, if the use of oil holes can directly measure the temperature of the outer ring of the bearing, it is more appropriate. Usually, the temperature of the bearing starts to rise slowly with the operation, and reaches a stable state after 1-2 hours. The normal temperature of the bearing varies according to the heat capacity of the machine, heat dissipation, speed and load. If the lubrication and mounting are appropriate, the temperature of the bearings will rise sharply, and abnormally high temperatures will occur, at which time operation must be stopped and the necessary precautions taken. The use of thermal sensors can always monitor the operating temperature of the bearings, and realize the temperature exceeds the specified value of the automatic alarm household or stop to prevent the burning of the shaft accident.