Prediction method of oil leakage of FDBs using numerical analysis

 Application of a spindle motor using a fluid dynamic bearing (FDB) to hard disk drive (HDD) presents some technical problems. Oil leakage from FDB is one of serious problem that must be solved. In this paper, we discuss a technique used to predict oil leakage from FDB spindle motors based on results of lubrication analysis of FDBs. We conducted oil leakage measurement using FDB spindle motors differing in specifications for FDBs. Then, we analyzed the lubrication in FDBs fitted to the spindle motors used in the measurement. Analysis results were compared with oil leakage measurement results. An analysis result that showed a correlation with the amount of oil leakage was determined as an evaluation item. Use of this evaluation item makes it possible to predict the occurrence of oil leakage with a high accuracy. Received: 5 July 2001/Accepted: 1 November 2001