Making Cars with CFRTP: Cheap, and Ready for Volume Production

Jun 25, 2014
Motohiko Hamada, Nikkei Automotive Technology

The development of Carbon Fiber Reinforced ThermoPlastic (CFRTP) for automotive frames has accelerated sharply, with four research facilities active in Japan. The first to open was the University of Tokyo’s Low-Carbon Research Network Japan, established in 2009. In 2012, it was followed by three more institutions: the National Composite Center at Nagoya University, the Composite Materials Center of Gifu University, and the Ishikawa Carbon Fiber Cluster at Kanazawa Institute of Technology. With all four engaged in full-scale research now, the development of CFRTP is forging ahead.

How soon the material is ready for widespread adoption depends on these institutes. Even though it is said to be “low cost,” CFRTP requires considerably more capital investment into production facilities than existing Carbon-Fiber Reinforced Plastic (CFRP) technology. While the equipment investment is steep, large-scale manufacturing would pay that off and make low prices possible. It would be a sort of process industry.

Until the two components of epoxy are mixed for reaction, they are liquids with low molecular weights and low viscosity. The liquid seeps into carbon fiber smoothly, making manual fabrication straightforward.

The viscosity of polypropylene (PP), however, is about a thousand times higher than unset epoxy, which means forming large components such as automobile frames would require presses wielding forces on the mega-Newton (MN) order. Components with minor concavities could be formed with pressing force of 10 MPa, and significant hollows would demand 20 MPa, so a piece with an area of a square meter would require about 10 MN (1000 tf). The roof or front hood, at about two square meters, would be 20 MN (2000 tf), and for pieces with significant topology double that, or 40 MN (4000 tf).

Unlike CFRP, which is also useful in small-lot production, CFRTP is intended for use with large-capacity equipment. Researching the material itself requires a major capital investment, a bit beyond the reach of most universities or small pressed-component manufacturers. The result was collaborative research facilities. As none of the major automotive manufacturers has announced full-scale in-house investment into the field, development will rely on these four active R&D institutions.