Unloaded slider vibrations excited by air flow between slider and rotating disk

The authors investigate a severe flexure vibration which was observed in a previous dynamic load-unload experiment. The flexure vibration appears in both pitch and roll measurements. The frequency of this vibration is about 400 Hz, regardless of the disk rotation speed, and its amplitude becomes relatively large when the initial slider-disk spacing is between 50-100 mu m. In order to understand the mechanism of this flexure vibration, the authors investigate the motion of a slider with an emphasis on the flexure dynamics. They use a laser Doppler vibrometer to measure the slider's motion at various distances from the rotating disk, and compare the results with a finite-element calculation. It is found that the first mode of flexure vibration is a pure roll motion, and its amplitude is usually smaller than those of the second and third modes. The second mode is a diagonal motion that is closer to roll and the third mode is a pitch motion.>