Contribution of lubricant thickness to head-media spacing

In this work, we have studied the effect of lubricant thickness on magnetic recording, specifically, its effect on head-media spacing (HMS). In the experiment, a series of disks were first lubricated to various thicknesses ranging from 20 to 60 Å. Then, read/write recording tests were performed for each disk on one track near the disk OD with variable linear densities. Next, the lubricant was washed off from MD to OD using a solvent, so the thickness of lubricant at the OD track was reduced. The read/write tests showed that the read-back signal was enhanced after lubricant wash-off. Using Wallace´s equation, the HMS change was calculated and found to be proportional to the change of the lubricant thickness. This result conclusively establishes that disk lubricant indeed takes up HMS and must be accordingly accounted for in HMS budgeting