Study of head and disk interface in contact start/stop test

The dependence of takeoff velocity (for head and disk combinations) on head parameters has shown that the takeoff velocity depends primarily on the rail width and crown of the air bearing surface. No significant dependence of the air bearing surface was found. Measurements of static friction for similar disks and heads with different takeoff velocities showed higher static friction for heads with higher takeoff velocities. By plotting the static friction data versus sliding distance rather than the number of contact start/stop (CSS) cycles, it was found that the higher static friction observed for heads with higher takeoff velocities was greater than what would be expected if the head dependence of the static friction increase were solely due to the total sliding distance of the heads. The significant dependence of takeoff velocity on head crown is an important parameter to control for acceptable static friction after a large number of CSS cycles