A Comparative Study of Turning and Stationary Groove Journal Bearings for HDD Spindle Motors Under Transient Contact Conditions

This paper compares the turning and stationary groove configurations of oil lubricated journal bearings used in hard disk drive (HDD) spindle motors under transient contact conditions, such as at startup and shutdown. With rapidly expanding applications for HDDs, spindle motors are required to have lower friction and wear while driving more disks, and be downsized at the same time. It has been known for some time that the turning groove bearing outperforms the stationary groove bearing with regard to friction torque in steady-state operations. However, the friction and wear of the two configurations under the transient contact conditions are still not well understood. To clarify this, we used a model previously proposed and validated experimentally to determine the motion of the turning member in the bearing by simultaneously solving the nonlinear differential equations of motion, the pressure-compliance relationship of elastic-plastic roughness contact, and the average flow Reynolds equation. The different characteristics of the turning and stationary groove configurations are then discussed for both herringbone groove and multi-taper bearings.