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Aluminum Makers Fight Plastic Planes With New Alloys

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Metal is staging a comeback, at least in the aerospace world, where aluminum has been challenged by carbon-composites in the industry's perpetual war on weight.

As plane makers showed off their latest carbon-plastic airliners at the Paris Airshow this week, metal firms lobbied hard for new, lighter aluminum alloys.

Aleris International, for example, is developing an aluminum-magnesium-scandium alloy that it says is 5 percent lighter than conventional aircraft aluminum and could be ready for later production of next-generation Airbus A320neo and Boeing 737MAX jets.

Nearly 90 percent of the 9,600 aircraft on order with Boeing and Airbus are metallic, said Ingrid Jorg, senior vice president of Aleris, mainly because smaller jets won't use composite fuselages for decades, if ever.

"If you don't expect single-aisle planes to turn to composites before 2030, then there's a lot of demand," she said.

The advent of composites with the Boeing 787 looked likely to undercut the aerospace aluminum industry. But years of research into lighter, more useable alloys is coming to fruition. Their use could keep aluminum demand strong for years, particularly in Asia.

The new materials face tests in labs and regulatory approval. They are also more expensive than conventional aluminum. But aluminum's long use in aerospace means many properties are well known. And some new alloys can compensate for high cost with better manufacturing use.

The Aleris aluminum-magnesium alloy can be welded, for example, replacing millions of fasteners on aircraft, says Jorg. Some aluminum-lithium alloys can cut weight by 8 percent over traditional alloys.


Still, composites are a key feature of next-generation large planes that are the centre of attention at the Paris Airshow. The Airbus A350's maiden flight last week provided another showcase for composites.

Plastic composites account for half of the weight of Boeing's 787 Dreamliner and Airbus's A350, eroding aluminum's traditional dominance in materials for those planes.

This tussle in aircraft materials mirrors growing competition in car making between dominant material steel and aluminum, which is the lighter challenger in this market.

aluminum makers accept composites are firmly established in wide-body aircraft, but say that after a first rush of composite demand, plane makers are being more pragmatic about materials so they can fulfill hefty orders and avoid further program delays.

"We believe that the aircraft of tomorrow will be hybrid - there will be no full aluminum aircraft and no full composites aircraft," Christophe Villemin, head of aerospace and transport at aluminum products group Constellium, said.

Boeing's plans to use an aluminum fuselage on a future redesign of its 777 jet, rather than a composite design as used on the fast selling but heavily delayed 787, has brought welcome news for aluminum makers. Boeing said it is considering an aluminum-lithium alloy for the jet.

Boeing estimates the market for these mid-sized, twin-aisle jets as worth USD$1 trillion over the next 20 years.

aluminum firms such as Alcoa say their latest alloys are in line with composites in low density, and that they can make healthy margins even when losing volume share.

"The 787 generates for Alcoa over 80 percent higher value per shipset than the all-metal 767 that it is replacing, and three-times the ship-set value of a 737," said Olivier Jarrault, head of Alcoa Engineered Products & Solutions Group.


aluminum alloys have not been without teething problems. Cracks in the wings of Airbus's A380 super-jumbo have been linked to alloy brackets used to join aluminum and composite parts.

Such joining issues are a big area of development, with metal and plastics set to co-exist for some years, and Alcoa says its fasteners business already made up almost 30 percent of its USD$3.8 billion in aerospace sales last year.

In the segment of smaller, single-aisle planes, aluminum makers expect the metal's continued dominance and are talking up their experience in this high-volume market.

Because single-aisle planes can use thinner aluminum skins, composites don't provide as much weight benefit, said Matthias Miermeister, manager of field engineering at Aleris, which recently opened a USD$350 million aluminum factory in China to meet demand.

Overall expansion in plane manufacturing is expected to yield another record number of plane deliveries this year, and a long order backlog should sustain a similar pace for the rest of the decade, providing enough demand for metal and composites.

Composite suppliers boast the more spectacular growth as plane makers step up deliveries of new models. Hexcel says it averaged 12 percent annual growth in commercial aerospace sales between 2004 and 2012.

Yet global aluminum use in aerospace should grow about 2.4 percent a year between 2010 and 2020, and on average, the metal still makes up 70 percent of aircraft structural weight, Metal Bulletin Research analysts estimate.

"I don't see a real threat for aluminum in aeronautics in the 10 years ahead," Antoine Chacun, managing director of French brokerage Oddo Metals, said. "All our rolling mill clients seem to be at full capacity and looking to add more."