Static characteristics of thrust/journal combined type of aerostatic porous bearings

Aerostatic bearings have been successfully applied to ultra precision machine tools and precision measuring equipments because they have higher accuracy of motion and lower friction than another types of bearings. Spindles of these precision machines are generally supported by both journal and thrust bearings. However, spindles with separated thrust and journal bearings are hard to be miniaturized because separated tubing for both bearings are needed. Therefore, thrust/journal combined type of aerostatic porous bearings that have simpler tubing are proposed. In this paper, the static characteristics of thrust/journal combined type of aerostatic porous bearings with surface restricted layers are investigated theoretically and experimentally.