Dynamic instability of thermal-flying-height-control sliders at touchdown

With the wide application of thermal flying-height control (TFC) technology in the hard disk drive industry, the head-disk clearance can be controlled to as low as ~1 nm. At this ultra-low clearance, the air bearing slider is subject to relatively large interfacial forces, and it experiences more complicated dynamics, compared with the flying case. In this study we conduct a numerical analysis to investigate the dynamics of TFC sliders during touchdown. The general trend of the slider’s motion predicted by the numerical simulation qualitatively agrees with experimental findings. The touchdown process begins with a slight intermittent contact between the slider’s trailing edge and the disk, followed by a partial slider-disk contact at the trailing edge accompanied by a large pitch motion at the 1st air bearing mode; this pitch motion gets suppressed and the slider comes into stable sliding on the disk as the protrusion is further increased.