Bench testing of the blades produced at our Cameri facility, a centre of excellence for additive manufacturing, and mounted on the GEnx engine (which powers the Boeing 787 Dreamliner and 747-8) began on 31 January. This procedure also serves as a test-bed for new technologies for introduction on the latest-generation GE9X engine, which is currently under development and will be installed on the equally new B777-X.
The development process that culminated in TiAl (titanium and aluminum alloy) blades produced with EBM (Electron Beam Melting) technology being mounted on the turbine of this large engine began some time ago.
We have been liaising with our colleagues at GE Aviation on this project since December 2013, when we discussed with them the development program for TiAl blades, of which the engine test is a vital step. Following the test, our GE Aviation colleagues visited the Cameri facility to find out more about the innovative additive manufacturing technology.
After receiving initial approval of the project and the results obtained, we proceeded to the production stage. Between April and June 2014 a total of 92 unfinished blades were produced for shipment to Rutland, the GE Aviation facility in Vermont dedicated to TiAl turbine blades. Here they underwent milling, application of anti-wear coating on the fins, interlocking shrouds and blade mountings, and non-destructive testing.
A joint Avio Aero and GE Aviation team examined the data for the unfinished blades in Italy and the results of the non-destructive tests performed on the blades machined in Rutland. Based on these results, the go-ahead was given for the blades to be mounted on the engine in September 2014.
The blades were then assembled by IHI in Japan before being sent to Peebles, Ohio, where the endurance test has begun (measured for 500 hours over 3,000 cycles) and will continue in Avio Aero during April.
The response from Vermont was very positive and exceeded expectations. Our American colleagues showed that the additively manufactured blades are easier to machine than conventionally cast blades and display fewer defects during removal of the excess metal. They also offer good potential for lowering processing costs as they have a greater net shape (i.e. the shape is closer to that of a finished blade) than blades produced by conventional casting.