High fuel costs, the economic recession, government bailouts and ever-higher fuel efficiency standards combined to rock the automotive world to its foundations in the 2008-2010 time frame. The situation left OEMs highly motivated to lightweight their vehicles to improve fuel economy and, hopefully, sales as they anticipate the future fallout from the U.S. energy bill, passed in 2007. The legislation set corporate average fuel economy (CAFE) standards to their highest levels ever — they will rise to 35 mpge (miles per gallon equivalent), or 14.9 km per liter, by 2020 for OEM fleets, including light trucks. Although composites continue to be attractive replacements for steel as part of an overall material mix in an effort to lightweight automotive body panels, structural components and under-the-hood parts, some automotive OEMs say that composites must become even lighter to compete with aluminum in high-volume applications. Lighter is likely to mean carbon fiber reinforcement, and that fact has intensified an ongoing auto industry debate about cost and practicality.
Carbon fiber has secured a solid place in the supercar segment. McLaren Automotive’s (Woking, Surrey, U.K.) new MP4-12C sports car, for example, features a first-of-its-kind MonoCell, a carbon fiber composite chassis “tub” that uses technology transferred from Formula 1 racing designs. Although the tub’s primary function is to carry the main operating loads between the front and rear of the car and protect the passengers, it also meets requirements for corrosion prevention, overall structural stiffness and ease of access to the passenger compartment. The resin transfer molding (RTM) resin used to make the tub is supplied by Huntsman Advanced Materials (The Woodlands, Texas). Preforms are made from high-strength carbon fibers manufactured by Toray Industries (Tokyo, Japan). The preforms are made in two formats — noncrimp fabric (NCF) and woven unidirectional (UD) tape — with a small amount of cross-stitching to hold the assembled reinforcements together. Production will start in early 2012, with cars available for sale soon after.
Particularly in the U.S. auto world, carbon is considered not only too expensive, but also too difficult to process in a passenger-car production environment. In late 2010 and during 2011, however, three significant efforts were launched to develop carbon fiber composites for production vehicles, surprising doubters and advocates alike.
Automaker BMW (Munich, Germany) continues to be the most aggressive automotive composites integrator. In 2011 BMW formally unveiled a new business unit, BMW i, that will launch in the i3 and i8 cars in 2013 and 2014, respectively. The i3, formerly known as the Megacity Vehicle, is an all-electric, four-door car that features the first production carbon fiber composite passenger cell that helps keep the vehicle weight to 1,250 kg/2,756 lb. The BMW i8 is a sporty hybrid/electric that accelerates from 0 to 100 kmh (0 to 60 mph) in less than 5 seconds and boasts fuel consumption of less than 3 liters per 100 km (77 mpge) Its plug-in hybrid drive with a system output of 260 kW allows a range of up to 35 km/22 miles in electric mode — sufficient for most everyday journeys. For more dynamic driving or out-of-town routes, a high-performance three-cylinder gas engine kicks in.
Both cars use carbon fiber produced by SGL Automotive Carbon Fibers, a joint venture of BMW and carbon fiber manufacturer SGL Group (Wiesbaden, Germany). In September 2011, SGL Automotive Carbon Fibers opened a new plant in Moses Lake, Wash., that will produce 3,000 metric tonnes (6.61 million lb) per year of 50K carbon fiber tow exclusively for the i3 and i8. The passenger cells will be manufactured using a proprietary RTM process developed by BMW. When SOURCEBOOK 2012 went to print, it was unknown whether the exterior body panels on the cars will be made of composites.
Following the BMW/SGL joint venture announcement in late 2010, Toray Industries announced that it will start supplying Toyota Motor Corp. (TMC) and Fuji Heavy Industries Ltd. (FHI) with carbon fiber for car bodies later this year — the first use of carbon fiber for auto bodies mass produced in Japan. Toyota reportedly will use carbon fiber for the hood and roof of the Lexus LFA, a luxury sports car to be produced starting in December 2011. FHI will sell roofs made from carbon fiber as an optional item for its standard-class sports car.
In the U.S., carbon fiber supplier Zoltek Companies Inc. (St. Louis, Mo.) and automotive composites manufacturer Plasan Carbon Composites (Bennington, Vt.) are among 40 organizations who will benefit from the U.S. Department of Energy’s $175 million fund over the next three to five years to accelerate the development and deployment of advanced vehicle technologies. Zoltek received $3.7 million for its application titled “Development and Commercialization of a Novel Low Cost Carbon Fiber.” Plasan received $2.5 million to evaluate and validate models for predicting the crash behavior of carbon fiber composites by building and testing subcomponent structures. The company was also recently in the news for its new out-of-autoclave rapid-cure system for composites that reportedly deliver Class A structural parts 75 percent faster with 80 percent less finishing and significant reductions in energy consumption. Engineering manager and R&D director Gary Lownsdale says Plasan has “cracked the code” that allows the company to mimic what happens in an autoclave, without changing resin chemistry or reinforcement technology. At a July 28 press conference, Plasan demonstrated a 17-minute cycle time on a six-layer carbon fiber-reinforced polymer (CFRP) test plaque from press close to press open, shaving 73 minutes off the typical layup, vacuum bag and autoclave cycle time. The company has filed numerous methods patents and just filed a joint equipment patent with development partners Globe Machine Manufacturing Co. (Tacoma, Wash.), supplier of the unique rapid-cure press system, and Weber Manufacturing Technologies Inc. (Midland, Ontario, Canada), supplier of the thin-shell nickel-vapor-deposition tooling used in the process. Plasan officials expect to produce CFRP parts at 35,000- to 50,000-unit annual build volumes — several orders of magnitude faster than the currently known fastest time (see “Faster auto parts production to get government boost," under "Editor's Picks," at top right).