The bearing system is a crucial quality operation element for motor products, and bearing heating problems are often the main cause of bearing system collapse. The heating of bearings can lead to the degradation and failure of bearing grease, causing deformation of the inner and outer rings of the bearings, as well as the retainer. In mild cases, it can be a problem of bearing noise, and in severe cases, it can cause the entire motor to be scrapped due to erosion in the bearing system.

For basic series motors, there are relatively few problems with the bearing system, as long as regular maintenance and upkeep are carried out according to the motor's usage and maintenance requirements. For variable frequency motors, as well as low-voltage high-power and high-voltage motors, there are relatively many problems with the bearing system, which can be difficult to solve.

Summary and Analysis of the Causes of Motor Bearing Heating

(1) The matching problem between tolerance fit and motor operating conditions. We have conducted specific analysis and discussion on this issue in the special section on motor bearings, especially for different series of bearings, the normal working clearance needs to be controlled by the dimensional tolerances of related components. For example, the working clearance of deep groove ball bearings is best controlled as zero clearance or slightly preloaded negative clearance, while the working clearance of cylindrical roller bearings should be positive clearance, even if it is very small, We will not elaborate on this aspect here. However, in practical applications, there are often reasons why the bearing fit is not suitable, or the working clearance is not suitable due to interference fit, or there are bearing race problems caused by excessive fit clearance, which can cause the motor bearing system to collapse in a short period of time.

(2) The problem of bearing erosion caused by electrical erosion. This problem is also the problem of shaft current we talked about before. The necessary conditions for the occurrence of shaft current are Shaft voltage and closed circuit. For motors used under variable frequency conditions, as well as high-power and high-voltage motors, Shaft voltage of varying degrees will be generated. When Shaft voltage that the insulation performance of lubricant cannot bear occurs, large shaft current will form a closed circuit through the bearing, And it causes erosion problems to the bearing system components. The initial manifestation of erosion is bearing noise accompanied by heating. In a short period of time, the damage and heating problems of the bearing components can lead to serious failure of the bearing system.

There are many problems caused by shaft current, some motors may run poorly for a period of time, while others may experience serious faults within a few hours. Regarding this issue, in many cases it is considered a bearing quality issue, and repeated replacement of bearings will not solve the problem. Taking necessary measures during the design and manufacturing stages, as well as selecting high-quality frequency converters during use, are both very effective and necessary measures.

(3) Heating problem caused by unsuitable lubrication system. We have discussed this issue in many previous articles. One situation is that the design itself is not suitable, and the bearing oil chamber is too large and cannot form good circulation, which can lead to bearing failure; Excessive filling of lubricating grease leads to poor heat dissipation in the bearing system; The mismatch between the lubricating grease and the operating conditions can lead to thermal degradation or cold agglomeration of the lubricating grease, which can cause the bearing to heat up due to poor lubrication; Especially during the operation of the motor, regular maintenance and upkeep are particularly important.

(4) Bearing heating caused by motor temperature rise or operating environment temperature. Some motors are inherently deficient and have temperature rise issues, while others operate in harsh environments, such as air compressor motors operating in high heat environments, which poses a significant challenge to the bearing system. Considering this issue, comprehensive consideration should be given to bearing materials and grease performance to avoid quality issues in the bearing system.

Of course, there are many reasons that can cause quality problems in the bearing system, but as long as you hit the nail on the head and understand the root cause of the problem, you can fully ensure the safety and stability of the quality of the motor bearing system.