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 HGA's with different limiters were used in t he experiments. The dimple impacts, which reflect the close of separated di mple in unloading process, were observed in most of the tested cases by usi ng AE measurements. The head-disk impact was occasionally observed for HGA with gaped limiter under larger unload speed, by using electrical resistanc e measurements. By using LDV and AE measurements, the dimple impact frequen cies were characterized from the response of unloaded HGA to an impulse exc itation. FEM analysis shows that the HGA with separated dimple has two cant ilever mode frequencies, which are correlated with the measured dimple impa ct frequencies. It was also found that the effects of the difference of the two negative pressure sliders on the impacts features are not obvious, whe reas the effect of the limiters and the unloading condition are essential t o the impacts.