A Plastic Composite Car in Every Driveway

Gas Pump

Previously published in Plastics Engineering and posted with permission from the Society of Plastics Engineers.

In May 2014, BMW introduced the i3 in the U.S., an electric car that sold out immediately and now has a long waiting list. The i3 is the first mass-produced vehicle with a major component – the passenger compartment – made from carbon fiber-reinforced plastics. So… is this a big deal?

Yes. It’s a big deal.

Of course, plastics are nothing new in autos. Today’s autos are approximately 10% plastics by weight – but half the volume of each vehicle, on average, is actually made from plastics. Bumpers, door panels, seating, dashboards, carpeting, lighting, insulation, and more and more parts under the hood… The list grows every year.

And auto parts made with strong, lightweight carbon fiber-reinforced plastics (CFRP) are not new, either. But to-date, large-scale production of these high-tech parts has been a slow and expensive process, so CFRP auto parts largely have been employed in luxury or performance cars. For example, this year’s Dodge SRT Viper hood and Chevrolet Corvette Stingray hood and roof assemblies are made with CFRP.

That’s why the i3 is a big deal. After 10 years of research, BMW has developed a more affordable, mass-produced major car component made from CFRP – materials that are up to:

  • ten times stronger than steel,
  • fifty percent lighter than steel, and
  • thirty percent lighter than aluminum.

For those not familiar with these materials: what exactly is carbon fiber… and what are carbon fiber-reinforced plastics?

Carbon fiber is an incredibly small diameter fiber (or filament) – typically between five and ten microns in diameter – made mostly of carbon atoms. These fibers typically are bundled to form thread (or tow) that often is woven into a fabric.

The term “carbon fiber” when used in layman’s terms (such as in news stories) often refers to “carbon fiber-reinforced plastics” – that is, a composite made up of carbon fibers plus some type of plastic or combination of plastics, and perhaps some other materials. The process of combining carbon fiber with plastics is similar to adding rebar (“reinforcing bar”) to concrete, which creates “reinforced concrete.” The combination of carbon fiber and plastics results in materials with superior qualities, such as greater strength and durability.

Because“ carbon fiber-reinforced plastics” is a mouthful, many people simply shorten it to: “carbon fiber” or “carbon fiber composite.” And the “plastics” sadly get forgotten.

What’s driving this shift from traditional materials to plastics and plastic composites such as CFRP?

Fuel efficiency: In 2012, the U.S. government announced stringent new Corporate Average Fuel Economy (CAFE) standards. Our nation’s cars and light trucks must average 35.5 miles per gallon by 2016 – and a whopping 54.5 miles per gallon by 2025. The standards not only will help reduce auto emissions – they also should save some significant money at the pump.

As noted above, CFRP is much stronger than steel yet lighter, so car components using CFRP weigh less than their steel counterparts. Just a ten percent reduction in vehicle weight can increase fuel efficiency six to eight percent over the life of today’s cars. This “light weighting” therefore can save a lot of gasoline – plus help automakers meet CAFE standards.

Safety: Lightweight plastics already play an integral role in many auto safety features: seat belts, air bags, interior cushioning, crumple zones, bumpers, safety glass, and so on.

Composites can build on that role. CFRP auto components have a much higher energy-absorption rate than steel, which can contribute to improved safety in a collision. BMW calls CFRP “an especially light and high-strength material that provides outstanding protection to vehicle passengers in the event of an emergency.”

As an example, race cars today are made largely with CFRP, which has led to reduced weight, improved performance, and enhanced safety. Like many other safety advances developed for the racetrack, CFRP components now are headed toward mainstream use in the family car.

Innovation breakthroughs:

  • Like BMW, many automakers (e.g., Ford, Mercedes, General Motors) are investing heavily in CFRP applications, resulting in new technologies that allow these components to be produced more quickly at lower costs. For example, the new production process developed for the Stingray CFRP hood and roof resulted in a 66% reduction in cycle time. And as the volume of CFRP parts production increases, costs per unit continue to decrease.
  • Recent breakthroughs in research are expected to catapult CFRP and similar composites into the mainstream, making them much cheaper and faster to produce. The plastics industry recently helped fund research that now allows auto parts makers to predict the performance of plastic composite parts that use long, lightweight glass fibers in fast-cycle manufacturing. This “predictability” can speed up manufacturing and brings down costs. The next step in this research is designed to provide similar predictability for lighter, stiffer, stronger CFRP parts.
  • The federal government has been spending significant resources on research designed to drive down costs of CFRP. In addition, the White House in February announced funding to launch a new Advanced Composites Manufacturing Innovation Institute focused on advanced fiber-reinforced polymer composites, noting that “advanced composites could reduce passenger car weight by 50 percent and improve fuel efficiency by about 35 percent without compromising performance or safety – helping to save more than $5,000 in fuel over the lifetime of an average car at today’s gasoline prices.”

Plastics Industry Automotive Roadmap: Recognizing that wide scale adoption of plastics and plastic composites is critical to help automakers meet the new CAFE standards and sustainability goals, the American Chemistry Council in April updated its automotive “Roadmap.”

The “Plastics and Polymer Composites Technology Roadmap for Automotive Markets” lays out a plan to encourage collaborative projects that will improve the manufacturing and assemblage of new high-performance parts made with plastics. It’s designed to help plastic and composites suppliers enhance the properties of their materials, as well as improve production efficiencies to accelerate innovation.

The Roadmap goal: “By 2030, the automotive industry and society will recognize plastics and polymer composites as preferred material solutions that meet, and in many cases set, automotive performance and sustainability requirements.”

Those are big words. But as the Roadmap points out: “The plastics and polymer composites industry has a long track record of delivering strong performance and continues to pursue transformative innovations.”

Next: on to the family car

The marriage of carbon fiber and plastics already has contributed to advances in passenger jets (e.g., Boeing’s Dreamliner), race cars, motorcycles, helicopters – even prosthetic limbs, tennis rackets, fishing rods, and bicycle frames.

Based on research and development by automakers, plastics makers, and the government, CFRP now appears headed toward mainstream use in the family car.