The development of properties of audiovisual (AV) and office automation (OA) machines in recent years is remarkable, and the functions determined by their main rotary shaft (spindle) grow stricter from year to year. In particular, spindles used in hard disk drives start playing a key role in the higher densification of magnetic disks, and they determine the requirement for the nonrepeatable runout (NRRO) of bearings on the nanometer level. Previously, rolling bearings were used for spindles in small-size precision machines, but in recent years, a tendency of using hydrodynamic bearings showing still better NRRO properties appeared [1]. In many cases, the development and the designing of hydrodynamic bearings involve a simulation and an analysis performed by numerical calculations using a computer and the estimation of properties of resulting bearings. In the present work, first, a general method of numerical analysis of sliding bearings including hydrodynamic bearings will be outlined and then, some models (texture model, porous material model, and cavitation model) applicable to actual bearing systems are presented. The application of the models whose usefulness grows higher as more accurate analytical methods in the case of developing future high precision spindles is highlighted.
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