Traction Coefficients for Coated Bearing Races Lubricated With Teflon Transfer Films

Abstract

The paper evaluates different soft metal coatings for use in conjunction with teflon transfer films. The work was directed at angular contact bearings. The overall goal was to reduce friction within the bearings and thus increase operation time between engine maintenance beyond current time levels. The paper gives a mathematical model which accounts for elastic deflections in coating, film, and substrates. Predicted traction forces are in agreement with published data. Calculations show that traction coefficients reduce when the coefficient of friction is reduced and surface flexibility is increased. Teflon has a low coefficient of friction (f ≈ 0.10) against nearly all metallic surfaces and is relatively flexible even at cryogenic temperatures. In order to reduce traction coefficients with surface coatings in parallel with teflon transfer films, the coating must bring about a lower coefficient of friction or increase surface flexibility.