In practice, bearing damage or failure is often the result of a combination of multiple failure mechanisms. The cause of bearing failure may be due to improper installation or maintenance, defects in bearing manufacturing and its surrounding components; in some cases, it may also be due to cost reduction or failure to accurately predict bearing operating conditions.

Noise and Vibration

Bearing slips. Causes of bearing slippage If the load is too small, the torque inside the bearing will be too small to drive the rolling elements to rotate, causing the rolling elements to slip on the raceway. The minimum load of the bearing: ball bearing P/C=0.01; roller bearing P/C=0.02. In response to this problem, the measures taken include applying axial preload (preload spring-ball bearing); when necessary, a loading test should be performed, especially for cylindrical roller bearings, to ensure that the test conditions are close to the actual operating conditions; improve lubrication Under certain conditions, increasing lubrication can temporarily alleviate slippage (in some applications); use blackened bearings, but not reduce noise; choose bearings with lower load capacity.

Installation damage. The bearing surface strain caused by the installation process will cause noise when the bearing is running and become the beginning of further failure. This problem is more common in separable column bearings. In order to prevent the occurrence of such problems, it is recommended not to push in the cylindrical roller bearing directly during installation, but to slowly rotate and push in, which can reduce relative sliding; it is also possible to make a guide sleeve, which can effectively avoid the installation process. ‘s bump. For deep groove ball bearings, the mounting force is applied to the tight-fitting rings, avoiding the mounting force through the rolling elements.

False Brinell indentation. The symptom of the problem is that the raceway surface has indentations similar to improper installation, and there are many secondary indentations next to the main indentation. And the same distance from the roller. This is typically due to vibration. The main reason is that the motor is in a static state for a long time or during long-distance transportation, and the long-term low-frequency micro-vibration causes fretting corrosion of the bearing raceway. The preventive measure is that the fixing of the motor shaft needs to be further improved when the motor is packaged in the factory. For motors that have not been used for a long time, the bearings should be cranked regularly.

Install eccentric. The eccentric bearing installation will increase the bearing contact stress, and also easily lead to the friction between the cage and the ferrule and the roller during operation, resulting in noise and vibration. Causes of this problem include bent shafts, burrs on the shaft or on the shoulder of the bearing housing, threads on the shaft or locknuts that do not fully compress the bearing face, poor alignment, etc. In order to prevent the occurrence of this problem, it can be solved by checking the runout of the shaft and the bearing seat, processing the shaft and thread at the same time, using high-precision lock nuts, and using the centering instrument.

Poor lubrication. In addition to causing noise, poor lubrication can also damage the raceway. Including the effects of insufficient lubrication, impurities and aged grease. Preventive countermeasures include selecting the appropriate grease, selecting the appropriate bearing fit, and formulating the appropriate grease lubrication cycle and amount.

Axial play is too large. The axial clearance of deep groove ball bearings is much larger than the radial clearance, about 8 to 10 times. In the arrangement of the two deep groove ball bearings, the spring preload is used to reduce the noise caused by the clearance in the early stage of operation; it is enough to ensure that 1~2 rolling elements are not stressed. The preload force should reach 1-2% of the rated dynamic load Cr, and the preload force needs to be adjusted appropriately after the initial clearance changes.