Temperature of hard disk and critical condition for heat-induced demagnetization in head/disk continuous sliding contact

Finite element analysis of head/disk continuous sliding contact was performed to investigate temperature field and thermal stress field due to frictional heat using an axisymmetric thermal model. Characteristic temperature rise with sufficient sliding time was exhibited. Additionally, effects of sliding velocity and contact pressure as well as frictional coefficient on the maximum temperature rise and maximum thermal stress were examined. From the simulation results and the demagnetization temperature available, the critical condition for heat-induced demagnetization in magnetic recording disks was deduced. It is shown that, the temperature of the disk increases rapidly to frictional steady-state value and then slowly to the maximum value at the enclosed air. The temperature gradient of the disk falls after longtime heat conductivity and exchange in head/disk continuous sliding contact. Higher velocity or/and heavier load produce significantly higher temperature rise and thermal stress of the disk. Velocity and load resulting in the maximum thermal stress smaller than 1.2 GPa is the safe operating condition for the magnetic disk, at the same condition with temperature higher than 373 K it will lead heat-induced demagnetization.