The microtribological phenomena have important effects on microelectro-mechanical systems (MEMS), especially when relative motion is required (e.g. microactuators). From the design concept of self-acting bearings (e.g. the flying head in a magnetic recording system), some step-shaped bushings beneath the rotor of a micromotor are considered and analyzed quantitatively. The modified molecular gas lubrication equation (MMGL) is utilized to analyze the step-shaped bushings. The results show that the coupling effects of roughness and gas rarefaction are significant and important in the design of bushings.
