A new method of manufacturing a foil bearing using tools made by the rapid prototyping technology

Foil bearings are aerodynamic gas bearings that are increasingly used in high-speed oil-free turbomachines, such as microturbines or turboexpanders. One of the barriers to the faster development of this type of bearings are production difficulties. This article discusses the consecutive stages in the development of a new method of manufacturing a bump foil - a key part of foil bearings. The threedimensional (3D) printing technology called MultiJet Printing was used to make precise production tools. A new application of the chosen additive manufacturing technique made it possible to manufacture accurate forming tools, as described in the first part of the article. The forming tool allowed the bumps of the foil to be shaped without using a hydraulic or mechanical press. The next part of the article focuses on the experimental tests of the developed method. The tests were performed on three bump foils with different geometries. These tests were necessary to examine the repeatability of the shape of the bumps that were formed using the cold pressing. The results of the measurements are presented and discussed in the last part of the paper. Additionally, a numerical analysis was carried out and confirmed that all the steps of the plastic working process were performed correctly. The proposed method is very effective in forming foil bumps of practically any shape, with excellent accuracy and repeatability. The developed method allows for obtaining the desired shape of the bump foil in order to improve the static and dynamic properties of the foil bearing and the rotating system. In the near future, the proposed method can be considered for larger-scale production. (C) 2020 CIRP.