Surface roughness effects on flying characteristics of proximity recording heads

The purpose of this experimental study is to understand the effect of disk surface roughness on the flying characteristics of quasi-contact sliders. Three 50% tripad sliders mounted on type 850 suspensions were used with five thin film magnetic disks with RMS roughness values ranging from 1.25 nm to 3.07 nn at the testing radius. Relative spacing results indicated that the slider to disk separation at the slider trailing edge was not greatly affected by the roughness of the disk for disk speeds between 1 mps to 28 mps. It was observed that the slider-disk spacing at a point slightly forward of the slider's trailing edge is linear with respect to velocity throughout the range of velocities tested. Interferometric measurements of head-disk spacing at a point near the trailing edge as a function of linear velocity exhibit higher slopes when tested over smoother disks than they did for rougher disks. When the head is still in contact with the disk, this change in spacing can be directly attributed to changes in slider pitch. Since the spacing is Linear as a function of velocity, whether the head is in contact or flying, it is believed that the change in spacing is due mainly to changes in slider pitch. The result for the glass disk measurement of sparing vs. velocity had a slope very close to that as tested over a supersmooth disk.