BMW to Start Producing Their Own Carbon Fiber Wheels
BMW and green cars
German luxury car maker BMW has showed that it has serious electric vehicle plans with the BMW i3, which went on sale in late 2013, and the i8, which will be available for purchase in June 2014. Both cars are quite innovative and unconventional in many respects, and will undoubtedly shake up the electric vehicles market. They feature dynamic exterior design, and excellent fuel efficiency thanks to the EfficientDynamics technologies. One of the most impressive things about these cars is the fact that their passenger compartments are made of carbon fiber, making them the first mass-produced vehicles to have a carbon-fiber body.
Introducing the Carbon-fiber technology
During the development process of the i3 and the i8, BMW was testing other carbon-fiber technologies, and considered putting carbon-fiber wheels in the production models, but the EU didn't allow it, as it didn't think they met safety standards. Now, after BMW made some modifications to the wheels, it announced that they are pretty close to production, and should be offered as standard equipment in the i3 and the i8 by the end of this year. The reason why the automaker has been putting so much effort into developing carbon-fiber parts is that it's a very effective way to reduce a car's curb weight, which is particularly important for electric cars, since their large battery packs add a substantial amount of weight.
The carbon-fiber wheels will replace the existing alloy ones, which are 35% heavier. Carbon fiber reinforced plastic (CFRP) is one of the most lightweight materials – it's 50% lighter than steel, and 30% lighter than aluminum. In addition to being light, it's also incredibly strong and durable, and can withstand heavy impacts, as it's able to absorb much more energy than steel or other materials that are traditionally used for making wheels.
Safety may be the only concern
Franz Storkenmaier, BMW's lightweight construction manager, who developed the carbon-fiber wheels, said in a statement: “We save 25 percent in weight compared to a forged alloy wheel with the hybrid wheel and another 10 percent if it’s completely carbon.” In addition too the carbon-fiber wheels, he also made hybrid carbon-aluminum ones, which feature alloy spokes and a carbon fiber rim. The main concern about these wheels is whether they are safe enough, with a lot of people wondering how the material reacts to strong impacts, since it contains plastic, which is pretty fragile. But, Storkenmaier is adamant that stress risk for these wheels is negligible, and they are highly unlikely to get shattered in the event of a crash, which is what many people fear.
BMW has large reserves of carbon fiber that was left unused in the production process of the i3 and the i8, and considering that it's a very expensive material, they wanted to make to most of it, so they decided to make other components from it. They made a carbon fiber steering wheel, that features a carbon frame and a carbon skeleton, as well as a one-piece carbon-fiber propeller shaft, which is supposed to be offered in the new BMW X5. In the future, the German car maker plans to extend the use of carbon-fiber to other brands it owns, such as Mini and Rolls Royce.