Bearing overheating is a frequent problem during the operation of the motor, which is often caused by a variety of factors and is relatively complex to diagnose. If it is not handled in time, it can cause more serious damage to the motor, shorten its service life, and then affect the entire work and production process. In general, we consider the bearing to be overheated when the motor bearing temperature exceeds 95°C (80°C for plain bearings).
So, what are the main causes of overheating of motor bearings, and how can we solve these problems?
1.Rolling bearing mounting problems
The mounting accuracy of rolling bearings is not only related to its own manufacturing accuracy, but also closely related to the dimensional accuracy, shape and position tolerance, surface roughness and installation method of the mating shaft and hole. If the inner ring of the bearing fits too tightly with the shaft, or the outer ring of the bearing fits too tightly with the end cover, it will cause the bearing to rotate inflexibly and thus generate heat during operation.
SolutionEnsure that the installation accuracy and fit tolerance of the rolling bearing are within a reasonable range, and avoid over-tight or over-loose fit.
2.Grease issues
Improper selection, use, and maintenance of grease can all cause bearings to heat up. For example, grease can be lubricated by poor quality, deterioration or impurities.
Solution: Reasonable selection and use of grease to ensure that it is of good quality and has not deteriorated. At the same time, pay attention to adjusting the amount of grease to avoid too much or too little.
3.The axial clearance between the outer bearing cover of the motor and the outer circle of the rolling bearing
For large and medium-sized motors, if ball bearings are used at the non-shaft extension and roller bearings are used at the shaft extension, the rotor can be freely elongated when it is heated and expanded. However, for small motors, since ball bearings are used at both ends, if the gap between the outer bearing cover and the outer ring of the bearing is improper, the bearing may be heated due to excessive thermal elongation in the axial direction.
Solution: Adjust the clearance between the outer bearing cover and the outer ring of the bearing to ensure that it is within a reasonable range. If necessary, a tissue paper pad can be added between the bearing cover and the end cap.
4.Mounting problems with end covers or bearing covers on both sides of the motor
If the end caps or bearing caps on both sides of the motor are not parallel or the stops are not tight, the balls will rotate out of the orbit and heat up.
Solution: Reinstall the end caps or bearing caps on both sides, make sure that the stops are flat and rotated evenly with bolts.
5.Wear problems of balls, rollers, inner and outer rings, and ball frames
Severe wear or metal spalling of these components can lead to degraded bearing performance and heat generation.
Solution: Timely update the bearing parts that are seriously worn.
6.Problems with the connection to the load machinery
Poor coupling assembly, excessive belt tension, small pulley diameter, too far away from the bearing, and excessive axial or radial loads can all cause the bearing to heat up.
Solution: Check and correct the connection with the load machinery to ensure that the bearing is subjected to normal force.
7.Shaft bending problems
Bending of the shaft can lead to uneven stress on the bearing, which in turn can cause heating.
Solution: Try to straighten the bent shaft or replace it with a new one. If the shaft is severely bent, it is recommended to replace the motor with a new one to avoid further damage and safety hazards. At the same time, it is also very important to maintain and inspect the motor regularly, so that similar problems can be found and dealt with in time to ensure the normal operation of the motor and extend its service life.