Aluminum product developer Constellium wants to increase the percentage of recycled metal it produces for aerospace in a bid to realize both economic and environmental goals. The value of such alloys has grown with the addition of elements such as copper, silver and—critically—lithium. One kilogram (2.2 pounds) of aluminum costs about $2, while one kilogram of lithium—the lightest metal in nature—costs $100. Despite the small amount of lithium present in an aluminum-lithium alloy (about 2 percent), alloy prices rise easily—hence, the need to avoid scrapping turnings, for example.
“Last year, 77 percent of the aluminum alloys we produced for aerospace applications came from recycling,” Constellium director of technology and innovation Bruno Chenal said during a recent visit by AIN to the company’s factory in Issoire, France. Company targets call for the proportion of recycled aluminum alloys to reach 80 percent by 2015. “Recycling one pound of aluminum avoids 11.4 pounds of CO2 emissions,” Chenal added.
To increase the proportion of recycled aluminum, most efforts involve cooperation with customers. Constellium encourages Airbus, Boeing, Bombardier, Embraer and other clients to use a “closed loop” machining process, allowing the metal maker to salvage offcuts and calling for another near-term investment at the Issoire foundry—namely, another furnace. In addition, more and more plates undergo pre-machining at the supplier’s facilities.
Now that the company’s patented Airware product has found applications on the Airbus A350 XWB and Bombardier C Series, recycling has become all the more critical. Airware, which covers a range of patented recipes for alloys, production techniques and recycling processes, offers weight savings of as much as 25 percent, claims Constellium, thanks to the combination of the alloy’s reduced density and new design possibilities. Moreover, Airware extends heavy maintenance intervals to 12 years, thanks to better resistance to fatigue and corrosion.
Maintaining lithium content during the recycling process is a key benefit of Airware. A highly reactive metal, lithium used to be lost in the recycling process. Airware allows for the re-use of aluminum-lithium alloys in aerospace applications.
Constellium won contracts to supply light alloys for A350 wing structural parts. The materials will come in the form of sheets and extrusions. For Bombardier’s C Series, it has agreed to provide Airware plates, some of them pre-machined.