TEST OF TWO CERAMIC-BONDED SOLID-FILM LUBRICANTS ON SMALL, HIGH-SPEED BALL BEARINGS RUN IN VACUUM AND IN AIR.
Technical rept. 1 Oct 64-1 Feb 66,
GENERAL DYNAMICS/FORT WORTH TEX NUCLEAR AEROSPACE RESEARCH FACILITY
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Two ceramic-bonded solid-film lubricants, MLF-5 and MLF-9, have been tested in air and in vacuum as the lubricant for size R3 ball bearings used in servomotors operating at 6000 rpm. A coastdown tester with ten servomotors that could be run simultaneously was used. The coastdown time was measured periodically, the field current in each phase of the two-phase servomotors was monitored, and the time to bearing failure was determined. In the test performed in air, bearings lubricated with MLF-5 failed in from 16 to 49 hr, the average time to failure of five servomotors being 27 hr. Bearings lubricated with MLF-9, when run in air, ran a minimum of 244 hr. and one servomotor was running when the test was terminated at 505 hr the average run time for the five sets was greater than 422 hr. Two tests were run in vacuum with widely differing results. The MLF-5-lubricated bearings five servomotors each test ran an average of 145 hr and 75 hr MLF-9-lubricated bearings in the same tests ran an average of 23 hr. and over 512 hr. In the second vacuum test the earliest failure of MLF-9 was at 44 hr, and two servomotors were still running well after 553 hr. No cause can be assigned for the wide variation in results, but two factors are considered to be of major importance 1 bearing run-in, and 2 shaft end-play. The bearings were double-shielded and considerable quantities of wear debris collected within the bearings.
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