A comparison of head-to-disk spacing fluctuation on hard and stretch-surface recording disks

The head-to-disk spacing between the slider and the magnetic recording disk is disturbed by impacting the disk for two different systems: a widely used 5 1/4 inch hard disk with a mini-Winchester type slider, and a developmental 5 1/4 inch stretch-surface recording (SSR) disk with a slotted spherical slider. Motions of the sliders and disks are measured by use of laser Doppler vibrometry, and the head-to-disk spacing variations are measured by use of the read-back signal modulation technique. The head-to-disk spacing is excited by the resonances of the suspension arm or the resonant vibrations of the disk in the hard disk system. On the SSR disk the air bearing resonances are much higher than other mechanical disturbances and the spacing variations are primarily limited to spacing increases from the steady flying height that resemble a bouncing motion of the slider. It is difficult to cause the air bearing to fail in the SSR system if cleanliness is maintained.