A study of the effect of frequency, amplitude, and load on fretting corrosion of instrument ball bearings

Abstract

Small precision ball bearings were vibrated for eight hour periods and coastdown was measured before and after vibration to determine fretting corrosion damage to the bearings. The load, frequency of vibration, and amplitude of vibration were each varied to determine their effects on the fretting corrosion damage. No lubrication was used on the bearings, and the test atmosphere was held constant.

A bearing was mounted on each end of a weighted shaft, and the outer race of the bearing was held in a small U-shaped housing. The housing was clamped to the shaker, and the shaker produced a vertical vibration of the bearing and shaft assembly. The vibratory load and the static load both produced a radial load on the bearings. The shaft was not rotated during vibration but was not restrained from rotation.

Test results showed an increase in damage accompanying an increase in either the load, the frequency, or the amplitude. Curves for damage versus load showed a rapid rise initially, a levelling tendency in the medium frequency range, and then a more rapid rise in the high frequency range. The effect of the amplitude on damage was observed to increase for increased loads. The damage generally increased at a slower rate than the increase in load.