MANUFACTURING OF A GAS FOIL BEARINGS FOR PALMED-SIZED TURBOMACHINERY

Abstract

Compliant Air Foil Bearings are used in a wide variety of applications. The versatility, ease of manufacture, and low cost of foil bearings are a few of the reasons foil bearing have been so thoroughly researched. Miniaturization of gas foil bearings has been explored using silicon parts with marginal success. An approach utilizing a well known micro-fabrication technique called LIGA (German acronym meaning Lithography, Electroplating, and Molding) is suggested as an alternative method. X-ray LIGA and UV-LIGA were explored and elastic foundations 200?m and 1mm in depth were made for an impulse turbine test setup. The main difference in between the two methods is resolution and depth that each is capable of producing. In addition, precision machine forming was used to create a top foil for the foil bearing. The predicted performance of the bearing was investigated through the orbit simulation method. A parametric study based on preload, as well as loss factor, was conducted in which the rotor speed was varied and the responses were used to create cascade plots. Both the response and cascade plots are useful to determine the onset of instability and the maximum operating speed of the foil bearing manufactured through LIGA. The unique features of the gas foil bearing introduced provide great promise in terms of its application considering the high stable operating speed is just above 1000 krpm.