Dry Lubricated Bearings for Operation in a Vacuum

Abstract

Ball bearings incorporating two different types of dry self-lubricating retainer materials were successfully operated in a vacuum over the pressure range of 1 × 10⁻⁷ to 2 × 10⁻⁸ (mm of H) torr for prolonged periods of time. A 20 mm bore ball bearing of AISI M-10 tool steel with a filled plastic retainer was operated over a range of temperatures from 100 F to 160 F and similar bearings with filled metal retainers were operated over a temperature range of −300 F to 450 F, at radial loads up to 75 pounds. Other ball bearings using both types of self-lubricating retainer materials were operated in electric motors in the vacuum environment. In selecting the dry self-lubricating materials for the ball bearing tests, plastics powders and composite materials were screened in an inert atmosphere to determine wear and friction characteristics. Each of the materials that exhibited desirable lubricating properties was then subjected to a vacuum at elevated temperatures to determine the rate of outgassing. These materials were then satisfactorily used as the dry self-lubricating retainers in the 20 mm bearings which operated in the vacuum environment.