A study of the air bearing effect on the lubricant displacement using an optical surface analyzer

Lubricant flow on a hard disk due to a flying head slider was studied using an optical surface analyzer. The tests were performed using a pico (1.25 × 1 mm) slider, and a regular modulation of lubricant thickness was observed, which was greater under the lower flying rail of the pico slider as a result of its roll.. The stronger modulation is thought to be due to the higher air bearing pressure under the lower rail. The frequency spectrum clearly showed distinct peaks at 100 and 140 kHz, which were consistent with the natural frequency modes of the flying slider motion detected by an LDV. We also found that the flying slider attitude affected the lubricant thickness modulation as did the disk texture. The lubricant modulation tended to follow the direction of the texture lines within the rail tracks of the slider. We conclude that the behavior of the lubricant layer depends strongly on the head flying motion.