Stability Analysis of Grooved Journal Bearings in High-Speed Hard Disk Drive Considering Thermal Effect

A micro-rotating machinery such as hard disk drive requires high efficiency and robust dynamics in high operating speed. Herringbone grooved journal bearings are widely used for this application thanks to their excellent dynamic characteristics. The clearance between sleeve and shaft is filled with fluid lubricant. However, the temperature of the fluid film rises significantly as the frictional heat, thereby the viscosity of the fluid and the clearance of hydrodynamic bearings decrease. In this article, the thermal expansion of the sleevepsilas inner radius was determined by LUO Zaipsilas method. It shows that the variation of clearance is an important design consideration which affects the stability of the hydrodynamic bearing of a hard disk drive spindle motor.