Reducing Head-Gimbal-Assembly Windage for High-Track-Density Hard Disk Drives

Abstract

The windage of a head gimbal assembly (HGA) is the flow-induced vibration affecting head slider positioning in the off-track direction. Reducing the windage is important for increasing the track density of hard disk drives (HDDs). To develop HGAs with a windage smaller than that of conventional HGAs, we examined the characteristics of HGA windage. We used a 12-mm (from the swage hole center to the dimple) HGA that had a maximum windage peak at 11 kHz. We put it in a spin stand and in a HDD and measured its windage with a laser Doppler vibrometer. The windage amplitude correlated well with the mean airflow velocity in the HDD (measured with a laser Doppler anemometer). Windage amplitude was also affected by fluctuation of the airflow velocity. Our results show that HGA windage can be reduced by increasing the distances between the rotating disk and the cover and the base.