DEVELOPMENT OF AEROSTATIC GUIDE WITH HIGH STIFFNESS AND HIGH PERFORMANCE MADE OF PARTIALLY POROUS FINE CERAMICS

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While both friction and wear are small in an aerostatic guide, the stiffness is comparatively small. Porous materials are used as a restrictor to improve stiffness in an aerostatic guide. In this study a partially porous ceramics, which was made with a special manufacturing process, was applied to the aerostatic guide. The boundary between the porous part and the fine part of the ceramics was seamless, and the porosity and the pore size were able to be controlled flexibly. The fundamental static characteristics of the aerostatic guide made of the partially porous ceramics were evaluated. In addition electroless plating was treated onto the porous ceramics surface for the purpose of obtaining high static stiffness, and the effect of plating on the static stiffness was examined. In addition the deflection of ceramics would occur by the pressurized air. The influence of deflection of porous ceramics on static characteristics was also evaluated. The obtained results were as follows : 1.Even in case of the non-plated ceramics, the maximum dimensionless static stiffness was enough to be used for the aerostatic guide. In case of the plated ceramics both the flow rate and the clearance decreased. Consequently, the high stiffness was obtained by the plating. 2.The minimum clearance where the maximum dimensionless static stiffness was obtained varied little with the deflection of porous ceramics. Therefore, the minimum clearance was suitable as the representative clearance. 3.The maximum dimensionless static stiffness and the load capacity estimated with the minimum clearance were decreased by the deflection of the porous ceramics. 4.The maximum dimensionless static stiffness and the load capacity could be arranged in order with the ratio of the deflection to the apparent clearance. 5.The partially porous ceramics employed in this study would be able to be applied to aerostatic guides.