The relationship between disk surface acceleration and head-to-disk interaction

One dominant trend in magnetic disk recording has been rapidly increasing areal bit density. This has been accompanied by lower head flying heights, which has caused the disk surface smoothness and flatness to be of greater concern. One technique for evaluating the surface is to fly a 3330 type slider equipped with a piezoelectric crystal instead of a read/write head. The output of the piezo-electric crystal is monitored as the full recording band of the disk surface is traversed. Isolated bursts of activity are interpreted as head contacts with flaws on the disk surface. However, even in the absence of such head hits there may be a high output from the burnish head, which we refer to as "burnish noise". Heads flying on such high burnish noise disks generate substantial audible noise accompanied by high head wear rates. In this investigation we have shown the relationship between burnish noise and the high frequency axial acceleration of the disk surface.