Ramp unloading "footprints"

Abstract

When ramp unloading, the radial distance a slider moves between first touching the ramp and lifting from the disk is called its ''footprint''. Footprints can detract from available recording area. Footprint values were measured for different sub-ambient style air-bearing designs and unloading parameters on a common suspension. Specifically, data was taken over a wide ranging values of PSA/RSA (slider pitch/roll static attitude respectively). Sliders with nominal PSA/RSA regularly lifted gracefully and unaided by suspension limiters within a few mils of travel. As PSA approach zero, however, sub-ambient lifting forces persist, leading-edge limiters engage and footprints extend to 12 mil. Increasing unload velocity increases footprints and slider dynamic vertical motion for nominal PSA/RSA. Surprisingly, for low PSA, slider motion decreases for increasing unload velocity when the leading edge limiter engages.