Material conversation

According to William Harney, automotive mouldings supplier Magna's executive director of research and development, the use of plastics is "moving from [car] body structure to the full frame". Schuler (01922 619100) is reporting progress in productionising carbon fibre reinforced composite plastics (CFRP) manufacture, while Japanese textile maker Teijin claims to have successfully developed what it says is the world's first mass production technology for carbon fibre-reinforced plastics for use in cars, by shortening the moulding process time required by 80% (see Machinery, April, page 46). But the metal guys aren't giving up. At the end of last year, the World Steel Association (WSA) highlighted that composites and lightweight metals such as aluminium and magnesium, used as automotive components, can create more greenhouse gas emissions than steel. These alternative materials produce 5 to 20 times more emissions per kilogram than steel, WSA says, and is therefore calling for life cycle assessments to ensure vehicle carbon footprint reduction is properly measured. This is more than an irony, because the use of composites and lightweight materials is driven by weight reduction to reduce carbon emissions in aircraft and cars, of course. Individual metals suppliers are also developing new materials. At last year's Farnborough Airshow, Alcan Engineered Products showed off new lightweight alloy AIRWARE, which combines aluminium, copper, lithium, magnesium and silver alloy. Alcan Global ATI and Canada's Bombardier have a long-term agreement for the exclusive supply of AIRWARE to provide the primary structure for Bombardier's new CSeries aircraft, as it happens. Indeed, AIRWARE will comprise more than 20% of all materials used in the CSeries. And claims for the CSeries are similar to the composite-focused Airbus and Boeing developments – 20% less carbon dioxide, 50% less nitrogen oxide, four times quieter in flight, 20% fuel burn advantage, and 15% improved cash operating costs versus current in-production aircraft of similar size (100-149 seats). The coup de grâce for this metal, however, is that AIRWARE is recyclable, although efforts to recycle composites are underway, while WSA could still cite steel's lower environmental impact versus lightweight metals. A steel fuselage, though? I don't think that's a likelihood. Alcoa has developed three generations of aluminium lithium alloys since Boeing launched its 787 effort. Quoted last year, Dan Goodman, director of marketing, Alcoa Aerospace, had this to say: "A few years ago, the industry consensus was that composites were the default material of choice. That is no longer the case – particularly for narrow body aircraft. At a substantially reduced risk, proprietary aluminium alloys and new aluminium-lithium alloys offer improvements in weight savings and enhanced strength at a lower cost." Alcoa and Commercial Aircraft Corp of China were said to be exploring advanced aluminium structural concepts, designs and alloys for China's 190-seat C919. Also at last year's Farnborough event, Allegheny Technologies introduced its new titanium ATI 425 Alloy. Employed in sheet form and with properties similar to Titanium 6-4 sheet, it is said to offer improved manufacturability and weight-saving potential. Additionally, new magnesium technology is said to produce sheet that has 200% higher strength and improved toughness, compared to conventional magnesium, while also providing the strength of carbon steel sheet at a quarter of the weight, and so looks likely to be of interest to auto makers. Composites might still seem to have more panache, but metals are trying to improve their image and attractiveness. First published in Machinery, May 2011