Manufacturing Effects in Microfabricated Gas Bearings: Axially Varying Clearance

Abstract

The effect of axially-varying clearance on microfabricated gas journal bearings is explored. This variation commonly arises from difficulties inherent to etching deep, narrow channels. Two types of clearance variation commonly observed in etched bearings are investigated: taper and bow. Both shapes are shown to have a detrimental effect on load capacity and bearing stability compared to a cylindrical bearing with the minimum clearance. For the same variation magnitude, taper is shown to have a more serious effect, including complete closure of the stability corridor at low speed for some cases. Methods are suggested for estimating variable-clearance bearing performance using cylindrical bearing data.