An experimental and theoretical investigation of disk damage caused by head-disk impact in loading process

This paper presents an experimental and analytical study of disk damage caused by head-disk impact in loading process. The electric resistance and AE measurements are used to monitor the head-disk contact. The long term ramp loading tests are conducted on a commercial tester. The disk damage are checked by using the tester, the optical microscopy, the AFM and the scanning reflectance analyzer. It was found that after many numbers of loading and unloading operations, the head-disk impact occurs due to the degradation of slider flying ability. However, even with a quite number of repeat head-disk impact, the tested disks does not exhibit noticeable wear and damage unless the impact number surpass some value. It demonstrated that the disk wear under the repeat impact is not progressive. A model is proposed to elucidate this phenomena. It shows that the wear exhibits the fatigue wear. The analytical results are correlated with the experiments and the previously published results.