Effect of Filtration on Rolling-Element-Bearing Life in a Contaminated Lubricant Environment

摘要

Fatigue tests were conducted on groups of 65-millimeter-bore ball bearings under four levels of filtration with and without a contaminated MTL-L-23699 lubricant. The baseline series used noncontaminated oil with 49-micron absolute filtration. In the remaining tests contaminants of the composition found in aircraft engine filters were injected into the filter's supply line at a constant rate of 125 milligrams per bearing-hour. The test filters had absolute particle re¬moval ratings of 3, 30, 49, and 105 microns (0.45, 10, 30, and 70 microns nominal), re¬spectively. Bearings were tested at 15 000 rpm under 4580 newtons radial load. Bearing life and running tract condition generally improved with finer filtration. The 3- and 30-micron filter bearings in a contaminated lubricant had statistically equivalent lives, approaching those from the baseline tests. The experimental lives of 49-micron bearings were approximately half the baseline bearing's lives. Bearings tested with the 105-micron filter experienced wear failures. The degree of surface distress, weight loss, and probable failure mode were found to be dependent on filtration level, with finer filtration being clearly beneficial.