Abstract
This paper is concise review on vibration of hard disk drives (HDD) spindle motors that carry multiple disks spinning at constant speed. The spindle motors could have ball bearings or fluid dynamic bearings (FBD). Theoretically, vibration of spindle motors consist of disk modes and unbalanced modes. Disk modes only involve disk deformation. In contrast, unbalanced modes involve deformation from the disks, hub, bearings, and the base. Experimentally, unbalanced modes are difficult to measures. Accurate measurements of unbalanced modes require careful considerations of excitation/measurement methods and locations.
