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5 most common causes of bearing failures in electric motors

2017-03-08

The following five factors can produce danages . By inspecing the damage bearing we can find some way to prevent the damages.


Electric erosion
When the current from one ring through the rolling element to reach another ring, may occur electric erosion or arc. The degree of damage depends on the size of the energy and its duration. However, the results are usually the same: pitting damage to rolling elements and raceways, rapid deterioration of the lubricant and premature bearing failure. In order to prevent damage to the current path, an electrically insulated bearing at the non-drive end is usually used. SKF offers two types of insulated bearings: INSOCOAT bearings and hybrid bearings.


Lack of lubrication
If the lubricant film between the rolling element and the raceway is too thin due to insufficient viscosity or contamination, metal and metal contact may occur. First check to see if the appropriate lubricant is used and the re-lubrication interval and quantity are sufficient for the application. If the lubricant contains contaminants, check the seal to determine if it should be replaced or upgraded. In some cases, depending on the application, it may be desirable to have a higher viscosity lubricant to increase the film thickness.
Vibration caused by damage
The motor that is transported in the absence of the rotor shaft firmly in place may vibrate in the bearing clearance, thereby damaging the bearing. Similarly, if the motor is in a quiescent state and subjected to external vibration for a period of time, the bearings may also be damaged. The bearings are fixed during transport in the following manner: Shafts are axially locked using bent steel in U-shaped shape, and the ball bearings are carefully preloaded on the non-drive end. And then use the belt to load the bearing radially on the drive end. In the case of prolonged downtime, the shaft is often rotated.
Improper installation and setup damage caused
Installation errors include installing a coupling half or pulley on the shaft using a hammer or other similar tool, misalignment, unbalance, excessive belt tension, and incorrect installation that results in overload. To prevent this from happening, check the alignment and vibration with precision instruments such as the SKF axis alignment tool and the Microlog Vibration Analyzer, as well as the appropriate tools and methods for installing the bearings.
Bearing load is insufficient
Bearings always need to have a minimum load to work properly. The damage will appear as a scrolling on the rolling element and the roller. To prevent this, make sure that the bearing is exerted a large enough external load. When using cylindrical roller bearings, it is important to remember this because they are usually used to withstand heavier loads. This does not apply to preloaded bearings.

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