Effects of Amplitude of Oscillation on the Wear of Dry Bearings Containing PTFE

The friction coefficients and wear rates of two dry-bearing materials have been measured during oscillatory motion at different amplitudes. The materials were composites incorporating fabrics of interwoven PTFE and glass fibers and differed in the pitch of the glass fiber at the surface. The worn surfaces were examined by SEM, EPMA, and XPS. The results show that when the amplitude of oscillation becomes less than the glass fiber pitch, third-body debris films on the counterface become increasingly nonuniform and surface roughness increases. The resulting trend toward increased bearing liner wear, however, is small provided that the amplitude of oscillation remains constant. The relevance of the results to the operation of airframe dry bearings operating under active control is discussed.