BMW’s carbonfibre future
It’s over three decades since carbonfibre made the crossover from aerospace to automotive, with the 1981 McLaren MP4–1 being the first F1 car built around a carbon monocoque. In 1992, the McLaren F1 became the first road car with a carbon body. But although the use of composite has spread since then, its cost and complexity has restricted its use to either expensive supercars, or for making smaller components on limited-run specials.
That’s set to change in 2013 with the launch of the BMW i3 city car — the first volume-produced model with a carbonfibre body. This will be accompanied by the considerably more expensive, but equally carbon, i8 sports car. And although BMW is initially going to reserve the use of carbon bodies for these new electric models, citing the need to offset the weight of batteries, senior execs admit that it’s ‘highly likely’ the technology will be used elsewhere in the range as costs fall. And, behind the scenes, other manufacturers are moving almost as quickly to a similar lightweight future.
The benefits of carbon may seem obvious, but it comes with substantial downsides. It’s around 50 per cent lighter than aluminium (when used to build a structure of equivalent strength), it doesn’t corrode and can be formed into intricate shapes. But it also requires a lot of energy to make and is relatively expensive. Even though the carbon in the i3 will cost only a third as much to make as the composite roof on the M3 coupe, BMW admits reducing the cost of carbon to that of aluminium is years away.
But carbon’s biggest problem, when it comes to mass-manufacture, is its lengthy production time. Steel or aluminium can be stamped into shape in seconds, and welded into intricate structures on a fast-moving production line. But even with the efficiency advances BMW claims to have made, it still takes hours to mould and set carbon parts.
There’s no faulting BMW’s ambition, though. The new Moses Lake plant in Washington state, USA, a joint venture with established carbon producer SGL, is set to become one of the world’s biggest carbon yarn producers. The yarn will be exported to another new factory in Wackersdorf, Germany, where the body panels for the i3 and i8 will be moulded and bonded. With two parallel production lines, Moses Lake will be able to make 3000 tonnes of carbon weave a year — eight per cent of total global production. There’s also enough space on site for six more lines if demand takes off. And it’s not just BMW. Audi is dropping some very broad hints about its own lightweight future, and VW Group has just taken a minority shareholding in SGL. Carbonfibre is set to go mainstream, and sooner than you think.
