What Do Carbon Fiber Car Components Have to Do with Plastics?

Professor Plastics

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Blue x-ray of car

Professor Plastics Has Two Words For You: Carbon Fiber.

When planning and building our new cars, automakers are increasingly turning to carbon fiber—the same type of material used in Boeing’s high-tech 787 Dreamliner airplanes. It’s said to be up to 10 times stronger than steel yet four times lighter.

Beyond autos and aerospace, carbon fiber is used in sporting goods, wind energy turbines, military applications and more. And its use is expected to double or even triple by 2020.

So … just what is carbon fiber? And why does Professor Plastics care? I mean, it’s not a plastic, right?

It’s true that carbon fiber is not itself a plastic. It’s an incredibly small diameter fiber (or filament) made mostly of carbon atoms. And I do mean small—usually between 5 and 10 microns in diameter (a micron is a millionth of a meter or about 0.000039 inches). These fibers usually are bundled to form thread (or tow) that often is woven into a fabric.

You might remember from chemistry class that diamonds—one of the hardest natural substances—are composed of carbon atoms arranged in a particular lattice. So it’s not surprising that carbon fiber is stiff, strong and light, plus resistant to chemicals and tolerant of high temperatures. Sounds ideal for making stuff.

Well, on its own, carbon fiber often is not ideal. It typically is combined with other materials to provide the properties needed for a race car chassis or airplane fuselage or prosthetic limb or tennis racket or fishing rod or bicycle frame.

Typically combined with what other materials, you ask? Plastics.

The term “carbon fiber” when used in layman terms (such as in news stories) most often refers to “carbon-fiber-reinforced plastics”—that is, a composite made up of carbon fibers PLUS some type of plastic. Or some combination of plastics. And perhaps some other materials. Since “carbon-fiber-reinforced plastics” is a mouthful, many people simply shorten it to: “carbon fiber” or “carbon-fiber composite.” And the “plastics” get forgotten. (So sad.)

Combining carbon fiber with plastics is sort of like adding rebar (“reinforcing bar”) to concrete, which creates “reinforced concrete.” The combination of carbon fiber and plastics results in materials with superman qualities, including greater strength and durability.

The combination of carbon fiber and plastics results in materials with superman qualities, including greater strength and durability.

As mentioned above, our new cars likely will see rapid growth in the use of carbon-fiber-reinforced plastics. (OK, let’s just call it CFRP.) To date, CFRP auto components—chassis, spoilers, roofs, hoods and many internal and external parts—largely but not exclusively have been employed in higher-end luxury or performance cars due to high manufacturing costs. Today many automakers (e.g., Ford, Mercedes, General Motors, BMW) are investing heavily in CFRP applications, now that costs are coming down and new technologies allow these components to be produced more quickly.

Why should we drivers (or passengers) care? Because increased use of CFRP can reduce vehicle weight, improve fuel economy and contribute to safety.

  • Weight/fuel economy: As noted above, CFRP is much stronger than steel yet lighter, so car components can be made lighter. That’s one reason Ford has partnered with Dow Chemical Company to expand CFRP use, with the goal of reducing auto weight 750 pounds by 2020. Just a 10 percent reduction in vehicle weight can increase fuel efficiency 6 to 8 percent over the life of today’s cars. That’s a lot of gas.
  • Safety: CFRP auto components can have a higher energy-absorption rate than steel, which can contribute to improved safety in a collision. As an example, race cars today are made largely with CFRP, which has led to reduced weight, improved performance—and enhanced safety. Like other safety advances developed for the racetrack, CFRP components now are headed toward mainstream use in the family car.

The growth in CFRP auto components will expand the already extensive and growing use of plastics in our cars. Today’s new cars already are made up of approximately 10 percent plastics by weight but 50 percent plastics by volume.

The combination of carbon fiber and plastics is poised to expand that ratio even further—while contributing to fuel efficiency and our safety.

Carbon fiber. Sounds like an ideal material. Just don’t forget the plastics …