Fabrication of key components in micro turbine engine by using micro electrical discharge machining (EDM)

The key components of micro turbine engine including micro air bearing and an integrative micro- rotating shaft that connected with a micro-compressor and a turbine were designed and fabricated. Nickel alloy (GH4169) was chosen as the material due to its high temperature resistance, instead of traditional non-metal material. They were machined by multiple micro-EDM technologies, such as micro-shaft with micro-EDM grinding, micro compressor and turbine with micro-EDM milling, and micro air bearing with micro wire electrical discharge machining. The surface quality and precision acquired by these methods was very good. The diameters of micro-compressor and turbine were both 2. 8 mm, and the height of each blade was 0. 4 mm, 0. 2 mm of thickness. The shaft was 1. 2 mm of diameter and 2. 0 mm of length. The micro gas journal bearing had 18 wedges, and 1.28 mm of inner diameter. The height of each wedge was 40 μm. The maximum rotating speed of micro turbine was about 40, 000 rpm.