Proper Bearing Handling Can Help Prevent Bearing Failures
Keeping the external surfaces and contiguous components (i.e., shafts and housings) contamination-free is also extremely important. Contamination on bearing faces or mating shoulder of the housings or shafts will cause a bearing pair to be out of parallel. This will cause the balls to run in a non-circumferential plane within the raceways, causing ball speed variations, ball skidding and binding between the races.
These phenomena increase friction which produces heat. Heat causes the lubrication to oxidize, which may result in premature bearing failure.