The effect of disk platter resonances on track misregistration in 3.5 inch disk drives

With the increase in track density and higher rotation speeds in hard disk drives, effects contributing to track misregistration (TMR) that heretofore have been negligible in the 3.5 inch form factor are now quite significant. One effect is the vibration of the individual disk platters at their natural frequencies. These resonances are driven primarily by internal windage excitation within the head disk assembly (HDA) during operation. This behavior is a characteristic of all 3.5 inch disk drives using 95×0.8 mm aluminum disks. The behavior is dominated by the disk material properties and geometry and not by the spindle, enclosure, or structural design. This disk vibration contributes a significant amount of track misregistration (TMR). Alternate disk substrate materials should be investigated as a means for controlling these effects