High speed electric motors must solve six issues,the second of which is the bearings.

The selection of bearings for high-speed motors is a key issue, and there are generally four categories to choose from: magnetic levitation, air bearings, sliding mechanical bearings, and ball bearing mechanical bearings. Magnetic levitation bearings are used in high-power applications, while air bearings are used in smaller power and size applications. Mechanical bearings often require oil lubrication and are limited in many oil-free applications.