Role of disk surface roughness on slider flying height and air-bearing frequency

The flying heights and air-bearing frequencies during the transition from flying to sliding were measured as a function of disk speed for thin-film disks with various roughness magnitudes using a multichannel laser interferometer and a laser-Doppler vibrometer. An acoustic emission transducer was also employed to detect head-disk contact. No significant differences in the flying heights or air-bearing frequencies were observed for different disk roughnesses at the tested speeds, but the landing speeds for the smoother disks were lower. It was found that the landing speed of a slider does not correlate with RMS surface roughness, but is more a function of asperity peak heights. There was no observed dependence of the air-bearing frequency on surface roughness at any speed. It is concluded that the effect of the surface roughness on the flying height and air-bearing frequencies is minimal, and the presence of isolated asperities affects the slider landing speed.>