A Study on the Efficacy of Airflow Mitigation Devices in Hard Disk Drives

The turbulent flow of air generated by spinning disks in hard disk drives (HDD) is known to be major contributor to undesirable vibrations of the head stack assembly (HSA). The continuing demand for higher capacities in HDD has resulted in a continual increase in areal densities. Densities in excess of 100 Gb/ in² have been demonstrated and it is widely projected that conventional technology will ultimately achieve 1 Tb/in². It is foreseeable that at such areal densities, a track density of 0.5 Million tracks/inch will be required, with each recorded bit being roughly 13 × 50 nm. Under such conditions, the tracking accuracy required is approximately 1.5 nm RMS (root mean square). These goals place stringent requirements on the positioning accuracy of the actuator while accentuating the need to mitigate the various sources of track misregistration (TMR).