Sleeve vs. anti-friction bearings: selection of the optimal bearing for induction motors

The decision between which bearing type to utilize is not always easy or even obvious. There is no choice in bearing selection on small motors (less than 200 HP), where only anti-friction bearings are readily available. Likewise, a choice does not always exist on larger motors in excess of 2000 HP, where various design requirements leave only the sleeve bearing (or tilting pad bearing) as a viable option. On intermediate size motors, a choice will have to be made. In general, anti-friction bearings (AFB) are less expensive, and result in a more compact motor. However, there are potential disadvantages associated with anti-friction bearings. The 'best' bearing decision depends on the details of the particular application. This paper explores the advantages/disadvantages of both types of bearings. Additionally, it provides guidelines to help select the best bearing for the application. Judicious selection of bearings will result in motor purchasing savings without sacrificing process reliability.