Study of contact bouncing vibration of flying head slider in near-contact region

We experimentally and analytically investigated detailed bouncing vibrations of a flying head slider in near-contact regine. In the experiment, we examined the effect of pitch angle on the unstable bouncing vibration in relation to ambient pressure by changing Z-height. As a result, we found that the hysteresis of touch-down and take-off pressure become small as the pitch angle increase even though the trailing spacing decreases slightly. From detailed measurement of the slider dynamics at the threshold of the bouncing vibration, we found that the trailing edge is first attracted to the disk and the first drop of the trailing edge becomes large as the pitch angle decreases. Moreover, we measured the 3-dimensional slider motion by using two laser Doppler vibrometers simultaneously, and found that the bouncing vibration is a coupled vibration between translation and pitch with a small phase shift. From the numerical simulation of a two-degrees-of-freedom slider model by considering a shearing force of the lubricant and micro -waviness in addition to the adhesion and friction forces, we could get a hysteresis of the bouncing vibration and two different instability processes as observed in the experiment.