STP771

    Evaluation of Powder-Processed Metals for Turbine Engine Ball Bearings

    Published: Jan 1982


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    Abstract

    Two different types of rolling element fatigue testers and a full-scale bearing tester were used in a program aimed at developing a highly fatigue-resistant powder-processed material (P/M) for use in turbine engine bearings. The testers were the single-ball machine evaluating 0.0238-m (15/16-in.)-diameter balls, a rolling contact fatigue machine evaluating 0.00953-m (⅜ in.) rods, and a full-scale bearing rig evaluating 140-mm-bore, 0.0238-m (15/16 in.)-diameter ball, angular contact thrust bearings.

    The two-element testers, used to screen three different P/M alloys and the baseline vacuum induction melted-vacuum arc remelted (VIMVAR) M-50 alloy, each produced essentially the same ranking for these materials. The best results, about twice the life of the baseline VIMVAR M-50, were achieved with P/M CRB-7, a 14 percent chrome corrosion-resistant alloy. P/M M-50 produced lives equivalent to VIMVAR M-50. P/M T-15, a 4 percent chrome alloy, exhibited lives ranging from that realized with the baseline material down to one third of that level. Based on these tests, CRB-7 was selected as the material out of which the balls and races for 20 full-scale 140-mm bearings were subsequently fabricated and tested. The tests were conducted at a thrust load of 34 872 N (7 840 lb) and at a speed of 12 500 rpm. A wear problem encountered in these tests was circumvented by nickel plating the cage guiding surfaces of the inner ring lands. The B10 rolling contact fatigue life realized with these bearings was equivalent to that expected for these same bearings had they been made of conventional VIMVAR M-50 material. These results were quite encouraging considering the fact that this was the first attempt at applying powder processing to the manufacture of aircraft-quality rolling element bearings.

    Keywords:

    powder metal, powder processing, ball bearing alloys, ball manufacture, ball bearing metallurgy, rolling contact fatigue, B, 10, life test, rolling element tests, single-ball test rig, rolling contact fatigue tester, RCF tester, ball thrust bearing, ball bearing fatigue test rig, bearing steels


    Author Information:

    Brown, PF
    Head and senior test engineer, Mechanical Technology section, United Technologies Corp., Pratt & Whitney Aircraft Group, Commercial Products Div., East Hartford, Conn.

    Bogardus, GA
    Head and senior test engineer, Mechanical Technology section, United Technologies Corp., Pratt & Whitney Aircraft Group, Commercial Products Div., East Hartford, Conn.

    Dayton, RD
    Group leader and mechanical engineer, Lubrication Branch, Air Force Wright Aeronautical Laboratories, Aero-Propulsion Laboratory, Wright-Patterson Air Force Base, Ohio

    Schulze, DR
    Group leader and mechanical engineer, Lubrication Branch, Air Force Wright Aeronautical Laboratories, Aero-Propulsion Laboratory, Wright-Patterson Air Force Base, Ohio


    Paper ID: STP36147S

    Committee/Subcommittee: A01.28

    DOI: 10.1520/STP36147S


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