Aluminum product developer Constellium (Hall 4 Stand H11) is increasing the percentage of recycled metal in the aircraft parts it produces, as it vies to lower the cost and environmental impact of using metals and to prove that composites are not the answer to everything. The French group’s latest Airware technology is now at the production stage for new airliner programs such as the Airbus A350 XWB and the Bombardier CSeries.
The value of alloys has grown with the addition of elements such as copper, silver and lithium. One kilogram (2.2 pounds) of aluminum costs about $2, while one kilogram of lithium– the lightest available metal–costs around $100. Despite the small proportions used in aerospace alloys (aluminum-lithium alloys contain around 2 percent lithium), alloy prices go up very easily. This has prompted Constellium to recycle more offcuts from machined work.
“Last year, 77 percent of the aluminum alloys we produced for aerospace applications were coming from recycling,” said Bruno Chenal, director of technology and innovation, during a recent visit to Constellium’s Issoire factory in France, where the proportion of recycled metal used is targeted to reach 80 percent by 2015.
Constellium changed its name from Alcan Engineered Products last year, soon after an ownership change. The new shareholders are Apollo Global Management (51 percent), Rio Tinto (39 percent) and the French government-backed investment fund, FSI (10 percent). The global aerospace, transportation and industry division has 42 percent of its business in aerospace, and its main customers are Airbus, Bombardier, Boeing, Dassault, EADS, Embraer, Korea Aerospace Industry, Lockheed Martin, Mitsubishi Heavy Industries and SpaceX. It employs 3,300 in Europe and the U.S.
Green and Lean
From an environmental standpoint, Chenal explained that recycling one pound of aluminum eliminates 11.4 pounds of carbon dioxide emissions. Measured in energy consumption, recycling one pound of aluminum uses just 5 percent of the energy needed for producing one pound of “new” metal. This is were ecologic and economic efforts meet. Energy accounts for one third of “new” aluminum production costs.
To increase the proportion of recycled aluminum, most efforts are done in cooperation with customers. Airbus, Boeing, Embraer, Bombardier and other clients are encouraged to have every machining process included in a “closed loop” for Constellium to salvage offcuts. The aluminum producer’s factories have about three quarters of their needs filled by such procedures.
In addition, more and more plates are pre-machined at the supplier’s facilities. This does not save turnings but at least most of them stay at the aluminum production facility. Logistics is the main limit of the recycling ratio, Chenal conceded, while another limiting factor is the possible presence of lubricant in the offcuts. There is a risk of creating oxides in the recycled metal, if the offcuts are not fully dried. Some aircraft manufacturers, such as Dassault at its factory in Seclin, France, are starting to introduce “dry” (without lubricants) machining processes.
Constellium’s latest technology has been dubbed Airware–a range of patented specifications for alloys, production techniques and recycling processes. Even the recycling methods for turnings are proprietary, and during the visit to the Issoire factory, journalists were not permitted to enter the brand-new Airware building.
For the Airware technology, Constellium claims a weight advantage of up to 25 percent, thanks to the combination of the alloy’s reduced density and new design possibilities. Moreover, heavy maintenance intervals are extended to 12 years, thanks to better resistance to fatigue and corrosion. One feature is that cracks tend to propagate less, leading to extended fatigue life of airframe structures.
Key to Airware alloy recycling is the ability the company recently acquired to keep the lithium. A very reactive metal, lithium used to be lost in the recycling process. More generally, “five years ago, we still could not recover all the valuable ingredients–lithium, copper, silver–we use in our alloys,” explained Christophe Villemin, president of Constellium’s global aerospace, transportation and industry division.
For Airbus, the company will supply light alloys for A350 wing structural parts. The materials will be in the form of sheets and extrusions. For Bombardier, it will provide Airware plates, some of them pre-machined, for the CSeries’ fuselage.
Constellium is continuing to research new alloys and processes. It is part of Europe’s Clean Sky initiative in a Dassault-led project. Chenal is also betting on aviation’s graveyards. Thousands of aircraft, stored in places like the Nevada desert, could become valuable commodities, he believes. Constellium estimates that the aluminum content of these aircraft could be $70,000 per airframe.