Effects of Radial and Circumferential Disk Features on Slider Dynamics

As the head-disk spacing is reduced in order to achieve higher areal density, dynamic stability of the slider is compromised by a variety of proximity interactions. One of the key factors is the disk topography, which provides dynamic excitation to the low-flying sliders and strongly influences the dynamics and stability of the slider. Several experimental and numerical studies have been done on the fly height modulation caused by the disk topography along the track (circumferential) direction. In this paper, we investigate the effect of the disk topography in the circumferential as well as the radial directions and use a new method to measure the 2-D (true) disk topography for disks with three different kinds of roughness and waviness features. We used a dynamic air-bearing simulator to simulate the slider dynamics over the measured topographies. Simulations used 1-D topographies along the track direction as well as the actual 2-D topographies. Comparison of the slider dynamics over the different 1-D disk topographies indicates a strong dependence on the circumferential roughness and waviness features. Further, the comparison of slider dynamics and frequency content over 1-D and the 2-D disk topographies indicates that the radial features, which have not been studied intensively until now, are also very important in determining the actual slider dynamics, as they dictate the variation of the adjacent tracks in the circumferential direction. The simulations with 2-D disk topography are more realistic than the 1-D simulations. Further, the effect of the radial features can be reduced through effective air-bearing system design.