Additive manufacturing and titanium aluminum are now a part of everyday language for our Engineering and Supply Chain colleagues—and many more. They identify materials and processes that are highly innovative for the aviation sector, and also bring substantial benefits, primarily in terms of weight (with a 50% reduction, from 580 g to 240 g for GEnx-2b blades, for example), a variable of obvious importance in this industry.
A colleague in the Pomigliano plant while working
Cameri is considered—by Avio Aero and all of GE Aviation—as the European center of excellence for additive manufacturing, and the production of TiAl blades in particular. Blades for low-pressure turbines are made using EMB (Electron Beam Melting) processes to create aircraft components (and more), starting from a pile of TiAl dust. Upstream of this process, there is atomization (which we mentioned in last June's issue of about magazine when we presented the new atomizer at Cameri), which “pulverizes” ingots of TiAl. Downstream, a variety of processing finishes the blade, such as thermal and surface treatments, mechanical processing and coating.
To date, various operations are contracted outside of Avio Aero, but we're gathering more experience to internally manage these processes.
The rotor blades of the GE9X (5th and 6th stage), for example, were manufactured in Cameri, assembled on the turbine in Pomigliano and delivered on time for the FETT (First Engine to Test) scheduled for the end of March. Cameri will also manufacture those for the SETT (Second Engine to Test) of the 9X.
And for Cameri, 2016 began with a new important order by the customer: two thousand blades for the 5th rotor stage to manufacture for around 20 GEnx-2b engines, which fly on Boeing 747-8.
“At this time, Cameri is the only plant qualified to manufacture 5th and 6th stage blades for the LPT GE9X. Indeed, this engine is created for the first time exclusively with TiAl blades made using EBM. For the GEnx, we're the second source: this means that the new TiAl blades made using EBM will replace the TiAl blades made using the spin casting process, and those on engines already in service,” explained Dario Mantegazza, Manufacturing Specialist in Cameri.
On the left, a GEnx LPT 6th stage rotor blade as it comes from Cameri plant and on the right after the manufacturing in Pomigliano plant
Focusing on the GEnx-2b blade order: by the end of this year, the Pomigliano plant will carry out all operations, from raw to finished product, using conventional (grinding, milling and airfoil profiling) and unconventional technologies (laser marking, alkaline attack/FPI, X-Ray, Shot Peening and APS coating).
“Conventional” processes define finite geometries, while “NDT processes—i.e. non-destructive testing, such as X-Rays and dye penetrant inspections—allow us to check the integrity of the individual component, whereas Shot Peening and APS coatings allow us to improve mechanical properties and wear resistance, by thermal spraying an intermetallic compound (Tribaloy T-800) to create an anti-wear barrier on the component in the areas most subject to stress during inflight operations.”
Even the GE9X program falls within the scope of process maturity for Pomigliano plant, as it concerns the final finishing required on the blades manufactured in Cameri.
All conventional and unconventional operations along with non-destructive testing (NDT) will shortly be outsourced, while Shot Peening and APS coating, which fall within the TRL/MRL program for obtaining process maturity, will be done in Pomigliano, as Giuseppe Petrone, Lead Manufacturing Engineering Specialist, explained to us from the Pomigliano plant.
Going back to the GEnX-2B program, the first batch of 30 blades was shipped in January from Cameri to Pomigliano, and the estimated effective processing time for one blade remains highly competitive. “We can confirm that already at the end of the second trimester of this year, it will be possible for Pomigliano to start processing the raw material arriving from Cameri, and we trust that we can bring the process to the level of readiness review by the end of the year,” Giuseppe Petrone concluded.
The challenge that the Pomigliano plant will have to tackle will be familiarizing themselves with completely new processing, on a base material that, before now, we haven't yet dealt with from a technological standpoint.
In Pomigliano, the NPI team (New Product Introduction) will collaborate with plant suppliers (after signing NDAs, Non-Disclosure Agreements), as well as with our expert colleagues at GE, during the most challenging stages of the process, with the goal of overcoming the technical complexities involved in this new type of processing.
The know-how and professionalism gathered by the two plants are great resources for Avio Aero, and can be adapted to all rotor blades, not just the GEnx and GE9X.