Load/Unload Systems With Multiple Flying Height States

Abstract

In hard disk drives that utilize load/unload technology, the slider loads onto the disk from hundreds of microns away before the slider settles into the designed flying height. Due to the forces acting on the slider after the transition from the unloaded state to the fully loaded state, the resulting flying height of the slider may be about two orders of magnitude higher than the intended nominal flying height. Under certain circumstances, the slider may never reach the nominal flying height required for proper operation of the magnetic recording process. In this paper, the existence of multiple flying heights is demonstrated and verified both by experimentation and simulation. The effect of some of the critical parameters is also identified by both methods. We show that necessary care must be taken to avoid unwanted loading sequences where the system may be unable to store or retrieve data.