Static characteristics of aerostatic guide made of partially porous ceramics

Abstract

While both friction and wear are small in an aerostatic guide whose bearing surfaces are separated by an air film, the stiffness is rather small. Porous materials are frequently used as a restrictor to improve stiffness in an aerostatic guide. In this study a partially porous ceramics, whose boundary between the porous part and the fine part was seamless and of which the porosity and the pore size were able to be controlled flexibly, was applied to the aerostatic guide. The fundamental static characteristics of the aerostatic guide made of the partially porous ceramics were evaluated. In addition, electroless plating was posited onto the porous ceramics surface for the purpose of obtaining high static stiffness, and the effect of plating on the static stiffness was examined. The influence of deflection of porous ceramics on static characteristics of aerostatic guide was also evaluated. The minimum clearance at the maximum dimensionless static stiffness varied little with the deflection of porous ceramics. The maximum dimensionless static stiffness was decreased by the deflection of the porous ceramics. The maximum dimensionless static stiffness could be evaluated with the ratio of the deflection to the apparent clearance. Even in the case of the non-plated ceramics, the maximum dimensionless static stiffness was around 0.4. In the case of the plated ceramics, the flow rate decreased by 1/10 or less and the clearance decreased by approximately 1/3. Consequently, high stiffness was obtained by the plating. The partially porous ceramics employed in this study would be able to be applied to aerostatic guides.

Keywords:

• Aerostatic guide
• aerostatic bearing
• partially porous ceramics
• static characteristics
• static stiffness
• deflection
• pressure distribution
• plating

Additional information

Notes on contributors

M Fujii

Masahiro Fujii is a professor of the Graduate School of Natural Science and Technology at Okayama University, Japan. His current research interests are tribology of modifi ed surfaces, improvement of rolling contact fatigue strength by surface modifi cation, tribology in severe environments, and numerical contact mechanics

A Yoshida

Akira Yoshida is an honorary professor of Okayama University and currently a professor of the Department of Mechanics and Robotics in Hiroshima International University and an Emeritus Professor of Okayama University, Japan.

S Liu

Sijian Liu received his PhD in mechanical engineering in 2006 from Okayama University, Japan.

H Nagashio

Hisao Nagashio works with Shinagawa Refractories Co, Ltd, Japan.

M Yoshikawa

Masahiro Yoshikawa works with Shinagawa Refractories Co, Ltd, Japan.