Reduction of disk flutter by decreasing disk-to-shroud spacing

Faster rotation speed in hard disk drives has increased disk flutter which causes head-positioning errors. The flutter reduction effects of various disk-to-shroud spacings in order to reduce disk flutter amplitudes have been investigated. In the experiments using 3.5 and 2.5 inch disks, we confirmed that the flutter amplitudes decrease when the spacing is less than about 0.5 mm. This effect was also confirmed when we changed the disk rotational speed and the shroud length.