7 Series Carbon Core

Lighter, Stronger, Faster – The Difference of BMW’s Carbon Core

BMW’s engineers are always looking for ways to improve the power and performance of their vehicles. Much of the time focus is put on the engine, but dozens of components get factored into the equation.

One of the more important factors is the weight of the car. Size plays a role, but the weight of body structure components also influence how heavy a vehicle is.

A while back BMW made an announcement that they would be using a Carbon Core frame in the 7 Series. This may not sound huge, but it’s a big departure from how vehicles have been constructed in the past.

What Every Driver Should Know About Carbon Core

Up until now the structural components of vehicles were largely made of steel. While it is strong structurally, steel is pretty darn heavy. A much lighter option is carbon.

The Carbon Core body structure actually consist of four primary components:

  • Carbon-fiber-reinforced plastic (CFRP)
  • Aluminum
  • High strength steel
  • Magnesium

The Carbon Core construction makes 7 Series models up to 286 pounds lighter than their predecessors. And of course, when a car is lighter that means it can go faster.

But that isn’t the only benefit of the Carbon Core frame. Hauling around a frame that’s 50% lighter also improves the efficiency. In fact, CFRP was first utilized in the i3 and i8 bodies to make them more fuel-efficient.

The models of the 7 Series met the highest standards of safety largely due to the Carbon Core construction. All of the components are strategically placed on the chassis to optimize safety, structural integrity and performance. At the center of it all is carbon-fiber-reinforced plastic. CFRP is primarily used on the roof, windshield and side pillars to make 7 Series models more rigid and lower the center of gravity for better handling. In addition to being incredibly strong, CFRP can:

  • Withstand high directional forces
  • Divert impact forces
  • Prevent the body from bowing inward on impact

CFRP was placed in 15 spots around the body for reinforcement in all the right places. All of this innovation recently won BMW the EuroCarBody Award. Not only that, the Carbon Core body of the BMW 7 Series got the highest score ever given.

Construction of the Carbon Fiber Components

The 7 Series is the first to use carbon fiber components that were produced on an industrial scale. Creating CFRP is an international endeavor that includes coordination between facilities in Japan, Germany and the U.S. It also requires both chemical and mechanical processes to make the super strong components.

First polyacrylonitrile (PAN) fiber is made in Japan. The thermoplastic fibers are then sent to a factory in Washington State. There the stablization/oxidation process is conducted by heating the PAN fibers to 390-590° F for about an hour. All the while the fibers are absorbing oxygen from the air. Next is the carbonization process. Oxygen-free ovens heat the fibers to1,830-5,500° F. The high heat process causes the fibers to shed the non-carbon atoms and the carbon atoms tightly bond into strings of black carbon crystals.

The newly formed strings are then flown to Wackersdorf in southern Germany. At a plant a short drive away from BMW headquarters, textile carbon fiber layers are shaped and molded into CFRP parts. To do this the textile carbon fiber is cut into the dimensions of the part, layered and then injected with resins. After baking for a short period everything has fused together to create one solid, incredibly strong CFRP part.

It’s worth noting that BMW makes their CFRP materials using renewable energy and recycled materials. So it’s also more eco-friendly.

Since BMW announced the expanded use of its CFRP components more automakers are following suit. Audi and Mercedes-Benz are both working to replicate BMW’s revolutionary body construction. In every sense of the word, Carbon Core is a game changer.