Numerical analysis of microwaviness-excited vibrations of a flying head slider at touchdown

The dynamics and stability of a flying head slider at proximity to and touchdown on a magnetic recording disk are attracting considerable research attention, because it is necessary to reduce the head clearance from the lubricant film to ~ 0.5 nm to achieve a higher recording density. As a succeeding study continuing the theoretical investigation of slider dynamics at touchdown, this study theoretically analyzes further details of the different behaviors of a practically applied head slider. The experimental touchdown behaviors at inner, middle, and outer radius positions in a commercially available hard disk drive are introduced. From the improved theoretical analyses, it is determined that different behaviors result from differences in air-bearing stiffness at the inner, middle, and outer radius positions. Moreover, it is found that the first half of the period for which a loss-of-contact signal is obtained corresponds to a light asperity contact state between the head and disk surfaces, whereas the latter half of this period corresponds to a flying state. It is thought that the former light asperity contact state can be well lubricated even at a high bond ratio, and that the light contact state can be used for future contact recording.