Analysis Of Causes For Motor Bearing Overheating And Damage (1)

The bearing system is a critical component of motor products. When malfunctions occur in the bearing system, bearings may suffer premature wear, disintegration and other issues due to overheating. As an important positioning part of motors, bearings are associated with other components, ensuring that the relative radial and axial positions of the motor rotor meet specified requirements.

Premonitory symptoms of Motor bearing system faults include abnormal noise or overheating. Generally, mechanical faults first manifest as abnormal noise, followed by overheating, and then progress to bearing wear-specifically characterized by louder abnormal noise, and even more severe problems such as bearing disintegration, motor shaft seizure and winding burnout.

What are the causes of bearing overheating and damage?

1)Assembly and Operation Factors

Anyone who has visited a bearing manufacturing plant knows that the production process control of bearings is extremely strict. Especially in high-quality bearing manufacturers, key bearing production processes are carried out in a highly clean environment. However, in the links of motor assembly, subsequent operation and maintenance, conditions are sometimes far from satisfactory.

For instance, bearing contamination caused by poor assembly environment, impurities (particles, other oils, water, etc.) mixed in lubricating oil (or grease), collisions and bumps to bearings during assembly, and abnormal stress on bearings in the assembly process can all lead to bearing failures in a short period of time.

In the operation phase, if motors are placed in humid or harsher environments, bearings may rust-a fatal problem for the bearing system.

Another issue related to the Motor bearing system is the sealing performance of the inner and outer bearing caps, namely the standardization of the machining of oil seal grooves. Non-standard machining or positive dimensional deviation of the inner and outer bearing caps can easily lead to foreign matter entering the bearings and causing faults.

2)Problems Caused by Improper Radial Fit of Bearings

All bearing products have initial clearance and operating clearance. Once a bearing is installed, especially when the motor is running, the bearing clearance refers to the operating clearance. Only when the operating clearance stays within the normal range can the bearing function properly.

In practice, the fit between the bearing inner ring and the shaft, as well as the fit between the bearing outer ring and the bearing chamber of the end cover (or bearing sleeve), directly affect the bearing's operating clearance or relative operation.

When the Motor bearing is in an excessively tight clamping state, the operating clearance will decrease, causing the bearing to overheat. Similarly, an overly loose fit can lead to bearing ring runout.

Positive dimensional deviation of the bearing chamber may result in outer ring runout, meaning circumferential relative movement occurs between the bearing outer ring and the bearing chamber. Negative dimensional deviation of the bearing seat diameter can cause inner ring runout, namely circumferential relative movement between the bearing inner ring and the bearing seat.

3)Binding Problems Caused by Stator-rotor Misalignment

Theoretically, when the motor stator and rotor are coaxial, the radial clearance of the bearings should remain relatively uniform during motor operation. If stator-rotor misalignment occurs, their center lines will intersect rather than coincide.

Take horizontal motors as an example-the rotor will not be parallel to the base surface, causing both end bearings to bear an external radial and axial force, which will inevitably lead to abnormal bearing operation during motor operation.