Influence of Disk Surface Bulge and Hard Disk Operating Conditions on Hard Disk Gas Film Heat Transfer

Abstract

When the hard disk is running, the cantilever of the magnetic head imposes a certain preload on the slider of the magnetic head to form a wedge space with the disk. When the disk rotates, the viscous gas enters the convergence gap so that the hydrodynamic pressure generates balance with the force acting on the cantilever, ensuring that the magnetic head flies above the disk in a stable altitude and forms a stable air film between the magnetic head and the disk called air bearing. When the flight altitude is low, the bulge on the disk surface will affect the pressure distribution of air bearing. Furthermore, the pressure affects the heat flux of air bearing by influencing the heat transfer parameters, such as thermal conductivity, dynamic viscosity, gas density, and the molecular free path of the gas. In this paper, heat transfer parameters' influence on gas film heat transfer were explored. Based on this, flathead slider and Tri-pad barotropic magnetic head slider were compared, and the effects of disk operating conditions at the average temperature of air bearing were also studied, such as pitch and roll angle of the magnetic head slider, the disk's speed, and the bulge on disk surface.