Five Millimeter Air Foil Bearing Operating at 350,000 RPM in a Micro Electric Motor Drive

This paper presents works performed at University of Texas at Arlington in designing and testing mesoscale foil bearing in diameter of 5mm. The elastic foundation for the foil bearings were manufactured using X-ray lithography and electroplating of Ni. Top foils were made of 0.5mm thick Inconel X-750. Two different designs of elastic foundation are presented, and foil bearings made of these elastic foundations were tested using a brushless permanent magnet DC motor drive up to 350,000rpm stable operation without any subsynchronous vibrations. After confidence was gained in the design, one of the elastic foundation was replicated using a micro sintering process using nano scale Ni-Fe powders. The micro sintering process can reduce the production cost of the elastic foundation dramatically by eliminating the expensive X-ray lithography and electroplating. The sintering process could reproduce the original elastic foundation within +−2 μm deviation from prediction. The preliminary results demonstrate the micro sintering process is a promising cost-effective manufacturing process of the mesoscale foil bearings.