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Cause analysis of bearing cage breakage and bearing loose

wallpapers Tech 2020-05-27
Bearings are important and key parts of motors. No matter if they fail to operate according to requirements during assembly, testing, or use, bearing noises, breakage, and even shaft failure may occur.
 
Especially for high-voltage motors, because it may also involve the erosion of the shaft voltage on the bearings, it must pay special attention and take specific measures. There are many reasons for the breakage of the bearing cage and the loose bearing. Ms. will summarize some possible reasons.
 
1 Analysis of the cause of bearing cage damage
● Lubrication is not in place. In the environment with lubricant, the bearing can increase the service life of the bearing and reduce noise. If there is no lubricant or the lubrication is not in place, the inside of the cage will be dry. This situation may also cause the cage to crack.
 
● Improper installation. If the installation is not in place, it may also cause the cage to break and fail. Therefore, bearing installation is also very important, and the installer must pay attention to it.
 
● Hard debris enters the bearing. The bearing should be kept clean and sealed. If the invasion of foreign debris or hard objects accelerates the friction coefficient between the cage and the outer ring and inner ring of the bearing, it may cause the bearing to fall apart.
 
● The load on the cage is not suitable. Insufficient installation causes the bearing to tilt, too much interference force, etc. It is easy to reduce the bearing clearance, soften the surface, intensify the friction and heat generation with the machine, and cause the surface of the bearing to fall off. In the frame, the resistance to the operation of the cage and the increased rotational load increase the wear of the cage. Such a vicious cycle may cause the bearing cage to break.
 
2 How to find the cause of damage from the traces of bearing damage
By checking the failed bearing, the root cause of the bearing failure can be determined to take the necessary corrective measures to prevent repeated failures.
 
● Electrical corrosion. When current flows from one raceway to another through the rolling elements, electrical corrosion or sparks can be caused. The degree of damage depends on the amount of energy and the length of time, but the results are often the same: that is, erosion pits on the rollers and raceways, rapid degradation of lubricants, and premature bearing failure. In order to prevent damage caused by current, insulated bearings or insulated bearing sleeves are usually used at the non-driving end.
 
● Poor lubrication or pollution. If the viscosity of the lubricant is insufficient or if impurities are introduced, the lubricant film between the rolling element and the raceway will become thin, which will lead to metal-to-metal surface contact. To avoid this situation, you should first check whether the correct lubricant is used, and whether the relubrication interval and dosage are suitable for this application. If the lubricant contains contaminants, check the seals and determine whether they need to be replaced or replaced. Depending on the application, in some cases, it is necessary to use a high-viscosity lubricant to increase the thickness of the oil film.
 
● Vibration. If the rotor shaft of the motor is not firmly fixed during transportation, vibration may occur inside the bearing clearance, which may cause damage to the bearing. Similarly, if the motor is exposed to a long period of external vibration when it is at rest, the bearings will also be damaged. The bearings should be fixed in an appropriate manner during transportation. If the motor is at rest for a long period, the rotor shaft must be rotated regularly.
 
● Improper installation and assembly. Common mistakes during installation include the use of a hammer or other similar tool to install the half coupling or pulley to the shaft, such as misalignment, unbalance, excessive tension of the belt, etc., which causes the bearing to overload.
 
● Bearing load is insufficient. Bearings always need a minimum load to work properly. The damage caused by insufficient preload of the bearing can be manifested as adhesive wear on the rollers and raceways. To prevent this from happening again, make sure that a sufficiently large external load is applied to the bearing.

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Tag: Bearings