Common factors and solutions for motor bearing overheating

Time：2021.02.25  Source：Roller Bearings Suppliers

Bearing overheating when the motor is running is a common fault, and its causes are various, and sometimes it is difficult to accurately diagnose. Therefore, in many cases, if the treatment is not timely, the result is often greater damage to the motor. The life of the motor is shortened, which affects work and production. When the motor bearing temperature exceeds 95°C and the roller bearing temperature exceeds 80°C, the bearing is overheated. The following are some common factors and solutions for motor bearing overheating.

1. The rolling bearing is installed incorrectly, and the fit tolerance is too tight or too loose.

Solution: The working performance of rolling bearings depends not only on the manufacturing accuracy of the bearing itself but also on the dimensional accuracy, form and position tolerances and surface roughness of the shaft and hole matched with it, the selected fit and whether the installation is correct. In general horizontal motors, a well-assembled rolling bearing only bears radial stress. However, if the inner ring of the bearing and the shaft are too tight, or the outer ring of the bearing and the end cover are too tight, that is, when the public surplus is too large, after assembly The bearing clearance becomes too small, sometimes even close to zero. In this way, the rotation is not flexible, and heat will be generated during operation.

If the fit between the inner ring of the bearing and the shaft is too loose, or the outer ring of the bearing and the end cover are too loose, the inner ring of the bearing and the shaft, or the outer ring of the bearing and the end cover will rotate relative to each other, causing friction and heating, which will cause the bearing to overheat. Usually, the standard moves the bearing inner ring inner diameter tolerance zone as the reference part to below the zero lines. The fit between the tolerance zone of the same shaft and the bearing inner ring is much tighter than the fit formed by the general reference hole. For more information about WSBC 22205 CC/W33 bearings, pls click here.

2. Inappropriate selection of grease, improper use and maintenance, poor quality or deterioration of grease, or mixing of dust and impurities, etc. can cause bearing heating.

Solution: Adding too much or too little grease will also cause the bearing to heat up, because when the grease is too much, there will be a lot of friction between the rotating part of the bearing and the grease, and when the grease is too little, dryness may occur. Heat due to friction. Therefore, the amount of grease must be adjusted to approximately 1/2-2/3 of the volume of the bearing chamber. Unsuitable or deteriorated grease should be cleaned and replaced with suitable clean grease.

3. The axial gap between the outer bearing cap of the motor and the outer circle of the rolling bearing is too small.

Solution: Large and medium-sized motors generally use ball bearings at the non-shaft extension end. The shaft extension end adopts roller bearings so that when the rotor is heated and expanded, it can extend freely. Because small motors use ball bearings at both ends, there should be a proper gap between the outer bearing cover and the outer ring of the bearing, otherwise, the bearing may generate heat due to excessive thermal elongation in the axial direction. When this phenomenon occurs, the front or rear bearing cover should be removed, or a thin paper pad should be added between the bearing cover and the end cover so that there is enough space between the outer bearing cover at one end and the outer ring of the bearing. Clearance. For more information about WSBC 22205 CC/W33 bearings, pls click here.

4. The end covers or bearing covers on both sides of the motor are not installed.

Solution: If the end caps or bearing caps on both sides of the motor are not installed parallel or the stop is not tight, the ball will deviate from the track and rotate and generate heat. The end caps or bearing caps on both sides must be reinstalled flat, and the bolts must be evenly rotated and tightened.

5. The balls, rollers, inner and outer rings, ball racks are severely worn or the metal peeled off.

Solution: The bearing should be updated at this time. 

6. Poor connection with load machinery.

The main reasons are a poor assembly of the coupling, excessive belt tension, inconsistency with the axis of the load machine, too small diameter of the pulley, too far from the bearing, excessive axial or radial load, etc.

Solution: Correct the incorrect connection and prevent the bearing from bearing abnormal force.

7. The shaft is bent.

Solution: At this time, the bearing force is no longer a pure radial force, so the bearing heats up. Try to straighten the bent shaft or replace it with a new one.

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