Lubricant flow under a flying head on a thin-film disk

The thickness of lubricant on magnetic disk surface decreases because of disk rotation and head flying. In order to simulate the lubricant flow on rotating disks in magnetic disk drives, we developed a finite-element-method code, which takes into account the effects of centrifugal force and the shear force caused by the air flow. Using this code, we studied the change in lubricant thickness on rotating magnetic disks with and without flying head. We first compared the measured and simulated decreases in lubricant thickness on rotating disks without flying head. They agreed well in two cases with and without radial air flow on the disk. We considered this proved our code. We then compared the measured and simulated changes in lubricant thickness under a two rail flying head. They had similar shapes with a valley under each rail. However, the calculated change was two orders of magnitude smaller than the measured change. This discrepancy between them must be eliminated to design future disk drives with simulation.