An experimental study of dimple separations and head-disk impacts of negative pressure slider in unload process

This paper presents an experimental study of the dimple separation and head-disk impact of negative pressure slider in unloading process. Two types of negative pressure sliders and HGAs with different limiters were used in the experiments. The dimple impacts, which reflect the close of separated dimple in unloading process, were observed in most of the tested cases by using AE measurements. The head-disk impact was occasionally observed for HGA with under larger unload speed, by using electrical resistance measurements. By using LDV and AE measurements, the dimple impact frequencies were characterized from the response of unloaded HGA to an impulse excitation. FEM analysis shows that the HGA with separated dimple has two cantilever mode frequencies, which are correlated with the measured dimple impact frequencies. It was also found that the effects of the difference of the two negative pressure sliders on the impacts features are not obvious, whereas the effect of the limiters and the unloading condition are essential to the impacts.