The Dependence of Roller Bearing Surface Fatigue on Lambda Ratio and Other Variables

A close examination has been made on the result of experimental research on surface fatigue in the low Lambda regimes. These experiments consist of two kinds. One is the endurance test of needle bearings, ball bearings and roller bearings with different surface and lubrication conditions. The other is the test with disk machines to observe peeling (or micropitting). The study shows that the Lambda ratio is not the only parameter which affects the surface fatigue of bearings. In most cases, the life ratio depends more strongly on the composite rms surface roughness than on film thickness. Thus, in addition to the Lambda ratio, the effects of asperity height/tip radius ratio, nominal contact pressure, mean separation, lubricant inlet starvation, surface defect, hardness and the compressive residual (or tensile hoop) stress on surface fatigue, should be taken into account.