High-speed wear lifetime analysis of instrument ball bearings

The instrument ball bearings often operate with high speed and light load. The common failure mode is wear-out occurring under insufficient lubrication condition. As a result, the vibration/noise and frictional torque will be enlarged, and the bearings lose accuracy and precision. In this article, the wear lifetime model of instrument ball bearings is established based on Archard's theory. A new wear coefficient curve is developed from the relationship of Archard wear coefficients obtained by a ball-plate experiment, which is related to oil type and load, with a certain lubricant film parameter (A). Then a computer program has been developed to calculate the location of pure rolling lines on the contact ellipse and obtain the contact stress and sliding speed on both inner and outer ball-raceway contact zones. Hence, the total wear time can be determined by the volume of wear with the allowable radial clearances. A 4000-h censored test of eight group samples, with its subgroup size of two bearings, has been conducted in special highspeed test rigs. The data of the experimental results were statistically analysed and compared with the model of wear lifetime. A consistent trend was found out between the experimental data and the proposed model.