Introduction to Basic Knowledge of Bearing Maintenance

Bearings, as one of the most vulnerable key components in small and medium-sized electric motors, their health status directly affects the operating performance and service life of the equipment. Once a bearing is damaged, it will not only cause increased running noise, intensified vibration, and abnormal temperature rise of the equipment, but also significantly reduce the equipment's accuracy. In severe cases, it may even lead to the complete destruction of the motor. To effectively extend the service life of bearings, during the installation and use of the motor, the following elements should be given special attention:
1. Installation of coupling
When using a coupling to connect the motor to the equipment, the axial force generated during the installation process is an important factor threatening the safety of the bearings. If the axial force is too large, it is very likely to cause damage to the bearing balls, raceways, and other components, thereby affecting the normal operation of the bearing. Therefore, for dimensions with interference fit, it is recommended to use the hot fitting method for installation. The hot fitting method involves heating the coupling to make it expand, then quickly fitting it onto the shaft, and allowing it to cool and contract to achieve a tight fit. This process can effectively reduce the axial force during installation. Additionally, it is also possible to choose to install at the non-shaft extension end of the shaft end face to avoid direct axial pressure on the bearing at the shaft extension end. For example, in a real case from a certain factory, due to the lack of attention to the axial force of the coupling installation, multiple motor bearings were prematurely damaged, and after changing the installation method, the failure rate of the bearings was significantly reduced.
2. Lubrication of bearings
According to relevant data, approximately 36% of bearing failures are caused by poor lubrication or improper use of lubricating grease. For small and medium-sized electric motors (frame size 80 - 355), even if no obvious abnormalities occur after continuous operation for six months, the lubricating grease should be replaced in a timely manner. This is because after long-term operation, the performance of the lubricating grease will gradually decline, and its lubrication, rust prevention, and sealing functions will weaken. If during operation, the lubricating grease shows signs of deterioration such as discoloration, hardening, or thinning, or if there is abnormal heating at the bearing area, it must be replaced immediately.
When replacing the lubricating grease, it is necessary to operate strictly in accordance with the standard procedures. First, use professional tools to thoroughly remove the old lubricating grease from the bearing and bearing cover to ensure there is no residue; then, use an appropriate cleaning agent to carefully clean the bearing and bearing cover to remove impurities and oil stains; finally, add an appropriate amount of new lubricating grease. It should be noted that the filling amount of the lubricating grease should be 1/3 - 2/3 of the space in the bearing chamber. Filling too much will cause an increase in resistance during the bearing operation and generate additional heat; filling too little will not provide sufficient lubrication protection.
3. Pollution protection
Bearings are precision parts and have high requirements for the operating environment. Once contaminants such as dust, metal debris, moisture, corrosive gases enter the bearing interior, they will accelerate the wear of bearing components, disrupt the lubrication state, and affect their normal operation. Therefore, the operating environment of the motor must strictly meet its protection level requirements. For motors with an IP54 protection level, it is necessary to ensure that the dust content in the environment is within the specified range and that solid foreign objects larger than 1mm cannot enter, and it must have a splash-proof water function. In dusty industrial environments, it is advisable to install a protective cover for the motor and clean the protective cover regularly to reduce the risk of pollutants entering the motor interior.
4. Fatigue prevention
Studies show that 34% of bearings fail prematurely due to fatigue. Overload operation, improper use, or poor maintenance can cause the bearing to bear excessive load or stress, accelerating fatigue damage. To prevent bearings from prematurely failing due to fatigue, the motor must operate under rated conditions and must not be overloaded. In practical applications, the motor should be selected based on the load requirements of the equipment to avoid "small horses pulling heavy carts". At the same time, a scientific equipment operation plan should be formulated to avoid the motor operating continuously at high load for a long time. In addition, conducting regular inspections and maintenance of the motors and bearings, and promptly identifying and addressing potential issues, can also effectively prevent the fatigue damage of the bearings.