Accurate touchdown power detection is a prerequisite for read-write head-to-disk spacing calibration and control in current hard\ndisk drives, which use the thermal fly-height control slider technology. The slider air bearing surface and head gimbal assembly\ndesign have a significant influence on the touchdown behavior, and this paper reports experimental findings to help understand\nthe touchdown process. The dominant modes/frequencies of excitation at touchdown can be significantly different leading to very\ndifferent touchdown signatures. The pressure under the slider at touchdown and hence the thermal fly-height control efficiency as\nwell as the propensity for lubricant pickup show correlation with touchdown behavior which may be used as metrics for designing\nsliders with good touchdown behavior. Experiments are devised to measure friction at the head-disk interface of a thermal flyheight\ncontrol slider actuated into contact. Parametric investigations on the effect of disk roughness, disk lubricant parameters,\nand air bearing surface design on the friction at the head-disk interface and slider burnishing/wear are conducted and reported.
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