Dynamic characteristics of hard disk drive spindles supported by hydrodynamic bearings

Most hard disk spindles currently used are supported by grease lubricated d eep-groove ball bearings, However, in the trend of increasing spindle speed and reducing size and cost, the shortcomings of ball bearing spindles, suc h as high non-repeatable run out, high acoustic noise and short life time a t high running speed, make them unsuitable for high performance hard disk d rives (HDD). On the contrary, the dynamic characteristics of hydrodynamic b earing spindles are superior to that of ball bearing spindles. Therefore, t hey are considered to be the substitute of ball bearing spindles in HDD. In this paper, a simulative setup of HDD is build up. The dynamic characteris tics of liquid lubricated spiral groove bearing(SGB) spindles are studied. The effects of both operating condition and bearing clearance are investiga ted. It is found that running speed of the spindle has significant influenc e on its dynamic performance, while the load has little influence. The effe ct of clearance is also evident.