Additive at Scale:
Avio Aero Flies into the Future
Additive manufacturing has been a small-batch endeavor as it’s developed over the last decades or so, impressive in its potential but underwhelming in its overall output. Not so anymore. Out here in the bucolic farmland of Cameri, Italy, in the Piedmont region, a company called Avio Aero is showing the world what additive at scale can really do – and how the innovative approach it’s taking in producing a lightweight and crack-prone material alloy in bulk can transform the aerospace industry.
That alloy – Titanium Aluminide (TiAl) – is being used to produce low pressure turbine blades with Electron Beam Melting (EBM) for GE Aviation’s GE9X jet engine, which powers the Boeing 777X jet. Prior to this breakthrough it was prohibitively expensive to make material alloys like TiAl, and they were also prone to crack. A small and dedicated group of design engineers, manufacturing engineers and machine operators are now turning out these parts cost-effectively and at scale. It is a huge leap for additive manufacturing itself, propelling the industry forward one TiAl part at a time.
"Designing and producing rotating parts for the hot environment in a jet engine is a true challenge,” said GE Additive Product Manager Oscar Angervall. “The available alternative is Nickel Alloy 718 with double the weight and increased fuel consumption as a result. TiAl is the perfect alloy for this application but very difficult to cast as it is prone to crack. Especially for these exceptionally large turbine blades, the scrap cost for casting is very high. EBM makes additive manufacturing a cost competitive alternative. In fact, today EBM is the only commercially available additive manufacturing method for TiAl."
Recently, our photographer visited Avio Aero in Cameri to document its growing operations producing TiAl blades, and we spoke to the people responsible for additive at true volume.
The Cameri plant is led by Giacomo Vessia, who oversees a young team that has pushed EBM for additive manufacturing to volume production levels.
“Overall, additive manufacturing like this is a revolution. We can now produce the parts we need – exactly when and where we need them, and at scale. This reduces time to market, inventory and transport costs.
“We are designing and fully realizing complex geometric structures in a single part. These outcomes were unimaginable only a few years ago.
“And it puts us in a new position: Before this, we would buy material castings from external foundries. They controlled the market but used traditional, expensive and unreliable methods of production. Now we are in control of our full value chain.”
While the impact of Vessia’s team’s efforts here is enormous, their footprint is small. A compact team runs operations, including experts from GE Additive. They closely collaborate with Avio Aero’s engineers on the ground to keep volume production going 24-7.
A worker hoists one of the small but heavy buckets filled with TiAL powder. He loads the powder into the Arcam EBM machines. Based on a 3D geometry model of the engine part, the machine applies layer after layer of the powder, melting each with an electron beam that solidifies the metal filings into one piece. One of the unique characteristics of EBM is that the process takes place at an elevated, controlled temperature and the build part can cool off slowly, which is key for producing quality parts using crack prone alloys. The EBM process also takes place in a vacuum build chamber, which guarantees a clean and controlled environment.
Once the design of the part is loaded into the Arcam EBM machine, the process takes three days to produce several fully-formed parts all in the same build. The machines operate around the clock, overseen by the operators here.
Overall, the temperature in the machines reaches roughly five times the cooking temperature of a pizza (which Giacomo has promised our hungry crew).
The GE9X LPT engine that these parts are produced for is ten percent more fuel efficient than its predecessor engine for the Boeing 777, the GE90. And using TiAl instead of the traditional nickel alloy for these parts results in a 50 percent weight reduction, again contributing to better fuel efficiency and lowering costs.
Angervall continues, "EBM is now a proven manufacturing process for the aviation industry, proving it can be used for one of the most challenging parts. As we now can mass produce LPT blades with EBM, anything is possible!"
An “Avio Aero Additive Ecosystem” has emerged in the region to help fill roles at this plant and others nearby, including local universities and training centers. Thirty one percent of Avio Aero’s employees are younger than 36 years old, and 22 percent are women.
Building on the current achievement of EBM additive manufacturing at scale, Avio Aero is now operating a full-time research and development lab, where engineers are testing materials and prototyping new approaches.
At the very beginning of Avio Aero’s efforts, it ran two machines total. At the beginning of 2019, the number had increased to 20. Currently, the outfit is operating 50 Arcam EBM machines around the clock in Cameri, A2X machines as well as the new Spectra H machines. Six more of the Spectra H machines are on the way, and there is room to expand even further. Over the next few years, Avio Aero plans to produce 60,000 turbine blades per year: full volume production using EBM additive manufacturing.