The largest growth opportunities in the automotive industry exist in body applications, where composites hold only a fraction of a percent of market share today. Demand for lightweight materials is increasing as automakers strive to provide consumers with appealing, fun-to-drive vehicles that simultaneously meet regulatory requirements for fuel economy and safety.
High-strength steel and aluminum have gained market share as manufacturers have looked for cost-effective methods to reduce vehicle weight. Despite its higher cost versus steel, aluminum gained nearly ten points of market share in mainstream vehicle body structures in the past decade, as manufacturers became more willing to pay a premium for weight savings.
Manufacturers seeking even more aggressive weight reduction have begun experimenting with carbon fiber composites, even though they typically cost several times more than steel or aluminum. The most prominent examples are from BMW. The automaker formed a partnership with carbon fiber supplier SGL prior to producing the i3 and i8 electric and hybrid vehicles, which both have CFRP intensive body structures. The i3, in particular, broke new ground for composites, as BMW has produced upward of 30,000 units per year, and it is sold at a price point well below the supercars normally associated with the material. The i3 platform alone is estimated to consume about 10 million pounds of CFRP annually, representing a major victory for the industry.
After using the i3 to develop manufacturing technology and a supply chain capable of handling high production volumes, BMW introduced the industry’s most advanced body structure with the 2016 7-series. The unique structure combines CFRP with metals, placing the expensive composite material exactly where it will benefit the vehicle most from a cost and performance standpoint.
Although CFRP accounts for only 3 percent of the 7-series body by weight, the material is credited with contributing 40 kilograms of weight savings, helping achieve fuel economy targets for the program. Due to the high cost of carbon fiber, it is likely that the practice of using the material sparingly – and in combination with more traditional automotive materials – is the way lightweight automobiles will be built in the future.
Thermoset CFRP has struggled to gain significant penetration in the market for automotive body structures for three primary reasons: part cost, cycle time and end-of-life concerns. Significant efforts are underway on each of these fronts, and much progress has been made. However, in order to achieve broad acceptance in the industry, several things must happen. First, it’s widely believed that the cost of carbon fiber will have to be reduced by at least a factor of two from its current level. In addition, cycle times of under one minute must be achieved. Finally, the material must by fully recyclable at the end of its life.