Hybrid polymeric bearings for space applications

This paper presents a theoretical and experimental analysis of the performance of hybrid ball bearings in which polymeric balls, rather than more conventional monolithic ceramic or ceramic-coated balls and steel raceways, are used. Three polymeric ball materials were selected for test, namely Delrin (polyacetal), PEEK (poly-ether-ether ketone) and Torlon (polyamide-imide). These were subjected to ball-on-disc tests, the most promising subsequently being subjected to bearing-level torque tests (in air and vacuum) and comparisons with predictions from the CABARET bearing analysis software of ESTL The programme confirmed the potential of hybrid polymeric balled bearings for space applications. In comparison to all-steel bearings lubricated by either lead or MoS2, hybrid polymeric bearings offer mass-savings of up to 70% and exhibit lower maximum/mean torque ratios. Though their DC torque levels can be high, and their stiffness is only around 15% of corresponding steel-balled bearings, it is considered that there may be a number of applications where hybrid polymeric balled bearings can be exploited.