SEED Guides Rolling element bearings Factors >

2.1 Reliability and Safety
Safety is concerned with the reliability of the bearing which depends on the service life demanded by the application. This will be a function of the running hours/day and the speed.

Reliability is also a function of quality and can be improved by de-rating the bearing i.e. reducing the actual loads it must carry. Bearings may fail in a number of ways, most of them gradual and with warning. Wear may occur as a result of high contact loads; seizure may occur as a result of poor lubrication or high running temperatures; fracture of ring or element may occur if fluctuating loads have caused a fatigue failure. Generally only the last of these is genuinely sudden.

Safety is greatly affected by maintenance, so the frequency of inspection and maintenance should be considered. The acceptable frequency of failure should be determined so that the quality and reliability of the unit is not over-estimated. It may be more acceptable to replace a cheaper bearing than to install one that has a very high quality.