Investigating the influence of geometric parameters on gas bearing static stiffness with experimental and numerical methods

Abstract

High‐speed spindle systems designed with gas bearings are widely used in electronic industries for printed circuit board drilling and semiconductor wafer cutting. This study focuses on investigating the stiffness of the gas bearing when the spindle itself is suspended under the supplied air pressure without rotating. The investigation utilized both the experimental ball impact test method and the numerical finite difference method to solve the modeling Reynolds equation for the stiffness evaluation respectively. The most frequently used condition of the 6 bar supply pressure is investigated experimentally for stiffness at the beginning of the study. It is then compared with the numerical results as derived from the theoretical calculated pressure distribution of the gas bearing. The validated numerical scheme is applied further to calculate the stiffness at other supply pressure and geometric variations. Moreover, it is also investigated for influences on the gas bearing stiffness by making a series of changes in the gas bearing design such as different orifice diameters, different length/ diameter (L/D) ratios, and varying types of gas restrictors including the pocketed orifice and inherent orifice.