Analysis of the oil injection process in fluid dynamic bearings of the spindle motor of computer hard disk drives

This paper numerically and experimentally investigates the oil injection process of fluid dynamic bearings (FDBs). Compressible air, which is governed by the ideal gas law, is introduced to model a nearly perfect vacuum. The two-phase flow of compressible air and oil is determined by the Navier?Stokes equation, the continuity equation, and the volume of fluid method. The proposed numerical method of this paper is verified by the oil injection experiment. This research discusses the possible sources of the air bubbles included in the lubricant of the FDBs in the oil injection process and proposes a novel oil injection process and FDBs to reduce the air bubbles.This research was performed at the Samsung-Hanyang Research Center for Precision Motors, sponsored by Samsung Electro-Mechanics Co. Ltd