HEAD DISK INTERACTION IN GAS-LUBRICATED SLIDER BEARINGS

The concept of critical operating conditions, the band of operating li nes which marks the transition from stable to unstable operation, is p resented to study the behaviour of the head-disk interface (HDI) under ultra-low flying conditions. The level of slider-disk interaction res ulting from intermittent contact at the HDI is used as the criterion f or this transition. Critical conditions have been determined experimen tally for three-rail mini-monolithic ferrite sliders flying in air and helium over a carbon-coated thin-film disk, and are compared to numer ical results obtained from a simple scaling analysis. A flying tester has been developed to investigate constant velocity, ultra-low flying height operation over a range of velocities and ambient pressures. Acc elerated wear of thin-film media has also been investigated with this apparatus. Utilizing a linear velocity slightly higher than the critic al value, it is possible to delay failure for several hours to several days. Worn slider and disk surfaces have been examined using optical and scanning electron microscopy, and debris has been characterized us ing Auger electron spectroscopy. These observations, coupled with meas urement of the friction force, have enhanced understanding of the wear process leading to failure under dry, unlubricated conditions.