An evaluation of various ball bearing lubricants operating in various environments /A status report/

Testing of both fluid and solid lubricants in small ball bearings is reported for a period of up to one year in various environments. The testing equipment, procedures and detailed results of five different lubricants, operating in a vacuum at ambient temperature, are described. Specially made motors were shimmed to maintain a 2.27 kg thrust load on both bearings, having a speed of 3600 rpm allowing 216,000 revolutions on each bearing per hour until failure. The commercial perfluoropolyether (PFPE-1) grease, having the best results, was recommended for long term bearing operation under hard vacuum conditions. It had an average life of over 8760 hrs. The ester based grease was recommended for moderate life requirements in vacuum conditions, while the silicone based grease and the fluorosilicone based grease were not recommended for vacuum operation due to extensive metal damage in the bearings.