Fundamental cavity patterns for flow and friction control in radial lip seals

It has been shown that deterministic micro-features on the shaft of a radial lip seal impact seal behavior. The effect of nickel film triangular cavity orientation on seal performance, in particular flow direction, pumping rate, and friction torque, is investigated experimentally. Cavity shape, area fraction, and depth are held constant while cavity orientation is varied. Oil drop test results are compared to those for conventional seals, i.e., plain stainless steel shafts, and shafts with an electroplated nickel surface, but no microcavities. Surface texture design was found to control both the pumping rate and direction. Preferential orientations pumped oil toward the base of the cavities while patterns in neutral, or non-preferential, orientations were found to reverse pump. In all cases, the presence of microcavities was found to reduce friction torque when pumping. The surface textures also enhanced pumping rates and reduced operating temperatures.