Carbon fiber in the automobile: at an impasse?
Photo credit: BMW
For at least 40 years, the auto market’s siren call has captured the attention of carbon fiber producers, with predictions of large-scale adoption repeatedly unrealized. The first high volume application I can remember was the filament wound driveshaft for the 1984 Ford Econoline full-size van, at about 40,000 units per year. In three years, it was out of production, cost being a primary factor. Over the following decades, carbon fiber shafts appeared on OEM platforms, but remained a relatively low volume product. Likewise, in the early 2000s, the carbon fiber craze grew as a multitude of supercars and sports cars took advantage of an abundance of low-cost carbon fiber, but these applications did not. did not translate into mainstream vehicles.
In 2013, with the introduction of the carbon fiber-intensive BMW (Munich, Germany) i3 and i8, and creating a dedicated supply chain to meet demand for fibers and components, we’ve waited (and waited) for other OEMs to follow suit, but none have. In 2015, we sang the praises of BMW’s “Carbon Core” multi-material philosophy to the general public. Series 7 platform, seeing this as the breakthrough needed to trigger a widespread proliferation of certain components made from carbon fiber. This concept progressed within BMW on the next iX SUV (see “BMW deploys multi-material carbon cage with 2022 IX vehicle lineup”), but BMW is the exception, not the rule. Finally, during the JEC 2017 world exhibition in Paris, I noted at least a dozen B-pillar prototypes all in carbon fiber or carbon / steel hybrids, the “killer app” for carbon fiber in automobiles. . Several producers have deployed the technology, but it has yet to really catch on on a global scale. Ultimately, more effort is needed to reduce costs so that this application can directly win over an all-steel solution.
At CompositesWorld Carbon fiber conference in Salt Lake City in November 2021, industry consultants Dan Pichler and Tony Roberts noted the impending end of production of the BMW i3 platform, and with it, a significant decline in the use of carbon fiber in the automotive industry. They also pointed out that there were no large-scale ‘announced’ carbon fiber automotive projects in today’s pipeline, projecting only a 2.4% CAGR through 2026, primarily for motorsports, customization and low volume niche platforms.
Wait. With the massive shift from internal combustion engines (ICE) to battery-powered electric powertrains, won’t mass savings become most important, given the extra weight of the batteries? Doesn’t that bode well for a strong demand for carbon fiber? The answer to the first question is yes, reducing the mass of the vehicle is still very important. And second, carbon fiber is still a consideration, but only if it’s cost effective. OEMs have several ways to reduce the weight of automotive components, including replacing steel with aluminum.
Composites are of great interest for lightweight battery housings in battery electric vehicles (BEVs), as evidenced by the Society of Plastics Engineers (SPE) Automotive Composites Conference and Exhibition (ACCE) (SPE, Danbury, Connecticut , USA) in November, where presentations on this topic, mainly focusing on fiberglass enclosures, attracted the largest audience. These enclosures are lighter than metal and can integrate the necessary thermal protection, flammability and EMI functions at a competitive cost.
Alternatives to high volume fraction carbon fiber structures also continue to provide economic benefits. More and more truck platforms are incorporating composite beds made from a UV resistant glass fiber sheet (SMC) molding compound. An IACMI project (Knoxville, Tenn., USA) with Volkswagen of American (Herndon, Virginia, USA) demonstrated a fiberglass SMC SUV tail lift that is 36% lighter than steel with costs recurring 9% lower. Another IACMI project demonstrated that adding 10% of recycled carbon fiber Polypropylene can reduce the weight of injection molded parts by 40% and the cost of parts by 30% compared to neat PA / PPE engineering thermoplastic. This indicates opportunities not only for recycled carbon fiber, but also for fibers made from lower cost precursors like PAN textile and coal tar pitch.
Is the use of traditional carbon fiber in the automobile at an impasse? Not quite, but don’t expect carbon fiber-intensive vehicles like the i3 to return to mass production. There is a narrow path to getting a carbon fiber structure with 50% fiber volume at a final cost of $ 10 / pound ($ 22 / kilogram), and this will require improvements throughout the production line. This will open up discrete opportunities in individual components like the B-pillars. In the shorter term, we can expect to see carbon fiber shapes, possibly pultruded, used as reinforcing elements in overmolded hybrid structures (including structural battery boxes) where glass-fiber reinforced polymers make up the remainder.
Composites have a great future in the automotive market, led by fiberglass, complemented by niche applications of traditional carbon fiber. For suppliers of recycled carbon fibers and fibers made via alternative precursors, the space of opportunity is considerably brighter.