History and trends in the development of motorized spindles for hard disk drives

Sensitivities of motor parameters important in determining cogging torque and radial imbalance force are shown using finite element modeling. These factors along with optimization of efficiency, methods for minimizing acoustics and optimizing heat transfer are of increased importance for future high performance spindles and disk drive designs. Factors including cost and power density are expected to slow the pace of form factor size reduction for high performance disk drives. Consequently, the benefit of improved dynamics through continued size reduction would not be realized at recent rates. This increases the need for improved spindle dynamics and performance. Spindle speeds will continue to increase to improve performance, although at a slower pace.