The following are the most common causes of bearing failure:
1. Lubrication failure
Lubrication should be one of the primary considerations in troubleshooting bearing faults. Because there are so many options, lubricants are often misapplied.
In order to properly lubricate rolling bearings, sufficient viscosity is required at operating temperature. Highly polished or faded bearing raceways and rolling elements indicate that the working surface does not have sufficient viscosity at operating temperature. The roughness of the contact surface is the result of insufficient oil film, which is another indicator of metal-to-metal contact wear.
If two incompatible greases are mixed, lubrication failure is inevitable. The change in the color and consistency of the grease illustrates this problem well.
Overlubrication can also be as serious as underlubrication. Insufficient lubrication can cause metal-to-metal contact, but excessive lubrication can cause heat build-up and friction as the rolling elements constantly try to push the excess grease away.
In addition to maintaining the correct oil level, be sure to check the bearing seals for problems. A failure of the seal usually allows the oil to escape, leading to premature wear and frequent replacement.
2. Pollution and corrosion
Dirt, sand and water are the most common pollutants, but chemicals and other corrosive substances can also cause problems. They dilute the oil film, lower the viscosity, and corrode the bearing surface, destroy the oil film and cause corrosion, forming thousands of abrasive particles.
According to "Bearing Failure: Barden Precision Bearings Causes and Solutions", cleaning the work area, tools, fixtures and hands helps reduce contamination failures. Keep the grinding operation away from the bearing assembly area and keep the bearings in their original packaging until you are ready to install them. Sealing is essential-a damaged or failed seal will not protect the bearing from contamination 1
3. Dislocation
Some (but not all) bearings can withstand the slight eccentricity between the shaft and the housing. However, in more severe cases, misalignment can be detected on the raceway of the non-rotating ring through a ball wear path that is not parallel to the edge of the raceway.
The most common causes of misalignment are: shaft bending, burrs or dirt on the shaft or bearing seat shoulder, the shaft thread is not at right angles to the shaft seat, and the end face of the lock nut is not at right angles to the threaded shaft1.
Severe misalignment can cause excessive vibration and load. In order to prevent bearing alignment problems, please check the shaft and bearing seat regularly, fill the bearing seat with gaskets if necessary, and use precision locknuts.
