Numerical analysis of microwaviness-excited slider vibration in proximity and contact regimes

Abstract

Vibration characteristics of a flying head slider in hard disk drives in proximity and asperity contact regimes attract much attention because head-disk spacing must be decreased to less than 1 nm in order to increase recording density. This study first elucidates head-disk interfacial (HDI) force as a function of static head spacing based on rough surface adhesion contact models and air-bearing force model. Then, selecting the most presumable surface force model which has a static unstable region at a thin lubricant thickness, microwaviness (MW)-excited vibrations of a single-degree-of-freedom slider model was simulated by the 4-th order Runge-Kutta method. It was found that the slider snaps-into a contact state from a proximity spacing state but the slider snaps-out to a flying state when the static head spacing is further decreased by increasing heater power. When MW amplitude is large, a drastically large spacing variation which contains various frequency components of less than 100 kHz appears in this unstable region. The spacing variation cannot be reduced to an allowable level even when the static unstable region disappears unless the minimum slider resonance is greater than about 100 kHz. It is discussed that these calculated results can explain the mechanisms of some experimental evidences reported in prior papers.

Keywords

• head disk interface
• rough surface adhesion contact
• diskwaviness-excited vibration
• mumerical simulation
• static instability
• jump phenomena
• nonlinear slider vibration
• nanocontact vibration