Analysis of Tracking Characteristics and Optimum Design of Tri-Pad Slider to Micro-Waviness

This paper describes optimum air-bearing design of a tri-pad slider in terms of tracking ability to micro-waviness based on theoretical analysis of the two-degree-of-freedom slider model and the distributed and concentrated air-bearing stiffness model. Although a short tri-pad type slider was introduced through the load/unload technique, we point out that this type of slider is superior to the traditional rail type slider in terms of tracking ability to micro-waviness. More importantly, the distance between head-gap position and the rear air-bearing center should be made as small as possible. The spacing variation due to lower mode resonance can be eliminated if the positions of front and rear air-bearing centers are located at the center of percussion. The resonance amplitude of the higher order mode in spacing variation can be reduced if the length of the rear air-bearing pad is designed to be $1.2∼1.3$ times the wavelength of the higher mode resonance frequency. Since the momental stiffness of the front air-bearing prevents the head-gap from tracking micro-waviness, the front air-bearing length should be made short or the ratio of rear to front air-bearing stiffness should be made large. If the resonance amplitude of the lower mode must be decreased, the front air-bearing length should be designed to be $1.2∼1.3$ times the wavelength of the lower mode resonance frequency.