Investigation of contact-induced vibration at low fly-height in hard disk drive servo systems

Along with the continuous growth of areal density in the HDD industry, contact of the slider with the media introduces new vibration sources, which are termed as contact-induced vibrations (CIVs). This paper investigates the properties of CIV at low fly-height in HDD servo systems. Our experiment results reveal that there are 3 main vibration modes at 441 Hz, 2110 Hz, and 2800 Hz, respectively, when the fly-height is reduced gradually. Further, the center frequencies of the CIVs do not change significantly (around 1.5%) with respect to different fly-heights. In terms of magnitude, at rotation speeds of 5400 rpm and 7200 rpm, the vibrations at frequency 441 Hz are much larger than the vibrations at 2110 Hz and 2800 Hz. For the scenario of higher speed, namely 10000 rpm, the vibrations at 2110 Hz are dominant. Moreover, we also observe that the faster the disk rotates, the larger the vibration is, and that vibrations have the largest magnitude at OD and the smallest at ID.