Rolling Bearing Service Life Based on Probable Cause for Removal - A Tutorial

A bearing service life prediction methodology and tutorial indexed to eight probable causes for bearing failure and removal are presented - including fatigue. Bearing life is probabilistic and not deterministic. Bearing manufacturers' catalogue (L10) bearing life is based on rolling-element fatigue failure, at which time 90% of a population of bearings can be reasonably expected to survive, and 10% to fail by fatigue. However, approximately 95% of all bearings are removed for cause before reaching their L10 life. A bearing failure can be defined as when the bearing is no longer fit for its intended purpose. For a single bearing, you can only predict the probability of a failure occurring at a designated time - but not the actual time to failure.