Investigation of dynamic head load and unload

Abstract

Several air bearing designs were investigated with respect to dynamic Load and Unload (LUL) induced vibrations. Different ABS designs as well as design changes in the suspension of heads were analyzed using an LDV scanning system as well as a Capacitance Probe unit synchronized together. It was observed that the head and suspension exhibited either stable or unstable flying height behavior during the Load or Unload process over a range of velocities to and from the ramp. The results were used to determine a range of LUL speeds that prevented unstable head resonances as well as disk dings and scratches. Most of these head resonances were due to dynamic instabilities of the suspension and head system. The resonance points were investigated at the center and trailing edges (roll and pitch sensitivity) of the head and suspension. A Polytec LDV and Capacitance Probe were used to follow the stable and unstable flying behavior of the head while stationary and the ramp was allowed to move. Methods are discussed to minimize and dampen out the most severe head/suspension vibration levels. Simulation of the flutter of the integrated lead suspension traces due to air flow and possible ways to damp the flow induced resonance is also discussed