Analysis and optimization of dynamic response of air bearing sliders to disk waviness

Flying stability has been becoming more critical for air bearing sliders with extremely low flying height (FH). Therefore, the effects of disk waviness on flying height modulation (FHM) cannot be neglected. This paper presents an analytical study on the mechanism of FHM of air bearing sliders due to disk waviness, and a design optimization for increasing waviness following ability of sliders. An analytical three-degree-of-freedom (3-DOF) model is developed, where the air bearings are modeled as six lumped linear springs and dampers. The purpose of this model is to develop a quantitative understanding of how air bearing sliders respond to disk waviness. The dynamic characteristics of the slider-air bearing system are then analyzed, and the closed-form frequency resonance function (FRF) of FHM to disk waviness is derived. The impact of disk surface features and the positions of the trailing pad, the side pads, the leading pads and the negative pressure center on FHM are also investigated using parametric analysis. The analysis results show that the improvement of the roll-off characteristics of the disk surface waviness can also decrease the FHM. In addition, shortening the distance between the trailing pad pressure center and the head position, moving backward the side pads and leading pads and forward the negative pressure center can increase waviness following ability of the slider. Finally, an air bearing slider is designed according to the proposed design strategies for reducing the FHM due to disk waviness.