Engineers at the Italian aerospace company Avio Aero, part of the GE Aviation group, have developed a process for Additively Manufacturing light-weight metal blades for jet engine turbines from titanium powder. The method builds the blades from a titanium powder fused with a beam of electrons accelerated by a 3-kilowatt electron gun.
The gun is reported to be ten times more powerful than laser beams currently used for printing metal parts. This boost in power allows Avio to build blades from layers of powder that are more than four times thicker than those used by laser-powered 3D printers.
As a result, one machine can produce eight stage 7 blades for the low pressure turbine that goes inside the GEnx jet engine in just 72 hours.“This is very competitive with casting, which is how we used to make them,” stated Mauro Varetti, advanced manufacturing engineer at Avio.
Avio developed the electron beam melting (EBM) technology together with Sweden’s Arcam. The idea was to improve the manufacturing of parts made from an advanced aerospace material titanium aluminide (TiAl). The material is 50% lighter than the nickel-based alloys typically used for low pressure turbine blades.
Blades made from the material can reduce the weight of the entire low pressure turbine by 20%. “Although the material is expensive, the weight savings and the fuel consumption savings tied to weight reduction more than pay for it,” added Varetti. Engineers can also change the shape of the blades and print different blades on the same machine in a quick succession, which would be laborious and expensive with casting processes.
GE will begin testing blades printed for the GEnx engine at its test facility in Peebles, Ohio, later this year. The parts will also go inside the GE9X, a new jet engine GE is developing for Boeing’s next-generation long-haul plane, the 777X.