Scaling Criteria for Slider Miniaturization Using the Generalized Reynolds Equation

Abstract

The current trend in the magnetic storage industry is the reduction of the slider size and the height at which the slider flies over a rigid disk. Lower flying heights are achieved by miniaturizing sliders and reducing the normal load. In this paper, force scaling criteria are determined for 3370 and 3370K sliders that are dynamically loaded or operated in contact start/stop mode. Two forms of the generalized Reynolds equation (the first-order and continued fraction formulations) are incorporated into the analysis. The new scaling equation relates the steady-state flying height to design and operating parameters such as the disk velocity, normal load, ambient pressure, and the shape and dimension of the slider rail. The resulting quadratic equation contains two slider design dependent parameters which are calculated from two full scale numerical solutions to the generalized Reynolds equation for the slider design of interest. The new scaling equation accurately fits numerical and experimental results over an extremely wide range of ambient pressures, normal loads, disk velocities, and slider size reduction. The utility of the scaling equation is that it can rapidly and accurately predict the load required to obtain a desired flying height at a given disk velocity for any slider geometry. The scaling analysis also has the ability to qualitatively account for surface roughness effects. The equation could be applied to the design of contact recording devices, if surface roughness effects could be quantitatively incorporated into the analysis.