When the EU banned lead as an additive in aluminium alloys, a plant in Italy set out to find a substitute.
“Creating an alloy mix is like tailoring a suit,” says Sergio Sannicolo, location manager for Sapa Profili S.R.L. in Bolzano, Italy. Just as custom suits are designed for the wearer, the hard alloys used in the aluminium profiles produced by the Bolzano plant have to be suited to specific client needs. Since the Bolzano plant specialises in profiles for automotive and industrial applications (largely hard alloy screw machine stock for mechanical, electrical and electronic equipment), the alloys it uses need to fit the requirements of those industries.
Until recently, Sapa had used lead in its alloy mixes, because the addition of up to two percent lead helped enhance productivity in the manufacturing process. Lead reduced excess metal shaving and increased speed and accuracy. But two European Union regulations passed by the European Parliament in 2002 and 2003, coming into effect in 2006 and this year, essentially prohibited lead as an additive in aluminium alloys. (Up to 0.4 percent lead is still acceptable, but only if it’s already present in recycled aluminium.)
“These edicts created significant problems for our industry,” Sannicolo recalls. Sapa would have preferred that the EUspecifies a substitute alloy, but Brussels left it up to the market. So for the past several years Sapa has focused on developing a lead-free alloy that would retain lead’s desirable properties. After many months of research, the company developed an alloy of aluminium mixed with magnesium, silicon, copper, tin and bismuth.
The additives, notably the tin and bismuth, mimic lead in that they enhance the characteristics of the alloy.
“The initial results were very good, just about as good as alloys with a lead additive, and the shaving problem was handled well,” says Sapa marketing analyst Claudio Del Furia. “Of course it’s not quite like lead, but it is rather satisfactory and much healthier.”
Once Sapa had an alloy mix it thought might work, it began testing the mix with a German client in the automotive industry to see how it actually performed. The client was so pleased that he has ordered 600 tonnes of the new alloy for 2009, notes Sannicolo.
“We would say that we have reached the 80 percent mark in terms of a solution to the lead-free issue.”
Nevertheless, Sapa continues to work on the alloy to refine it. Research is ongoing at the company’s research centre in Sweden to reduce the waste from metal shavings, as well as improve quality control. Automotive processes are high speed and highly automated. If a metal is of inferior quality, it threatens both the speed of output and the quality of the final product.
“We should always be striving for perfection, no?” says Sannicolo.
Text: Claudia B. Flisi