Largely, however, use of wood for anything other than luxury trims was gradually phased out from the 1950s, as carmakers turned to all-steel bodies and plastic components.
Now, driven by the industry’s sustainability concerns, a new generation of plant-based materials is finding its way into modern cars. On Friday (11 April), natural fibre composite specialist Bcomp announced a collaboration with South Korean carmaker Kia to bring its flax-based composite materials to entry-level vehicles.
Unveiled by Kia’s designers at Milan Design Week ahead of an anticipated launch next year, the Concept EV2 includes Bcomp’s AmpliTex reinforcement fabric in its back seat shell and front seat substructures.
Described as “another step toward the mainstream adoption of natural fibre composites in automotive interiors” by Swiss firm Bcomp, the project builds on other automotive projects with Volvo, Polestar and BMW.
The company claims its materials offer many advantages over conventional options, including “exceptional strength-to-weight ratio, superior vibration damping, and significant CO₂ reduction”. Widespread integration into such a large and safety-conscious industry will not be straightforward, however.
From Silverstone to the school run
Bcomp’s automotive expertise started in motorsport, including a sustainability-focused collaboration with McLaren Racing on Formula One’s first natural fibre seat, which Lando Norris piloted to fourth place at the 2021 British Grand Prix.
The competition’s high intensity provided the perfect testbed for the firm to transition to the wider industry, where it is more often replacing plastic than carbon fibre. “There we bring other benefits, which is mainly significant potential for lightweighting,” says Johann Wacht, manager of business development, to Professional Engineering.
As well as woven AmpliTex, Bcomp also offers PowerRibs, a natural fibre grid used to reinforce thin-wall ‘shell’ components. Both can be made into ‘prepreg’ (pre-impregnated) composites to cut use of fossil-fuel based options.
Used in decorative parts as well as door panels and seatbacks, the manufacturing approach for components is determined by the production volume. Parts for hypercars and supercars often require autoclave processes, which involve a lot of manual work, while others use compression moulding instead.
In that process, Wacht says, a natural fibre weave is embedded in polypropylene, including bio-based options. A second ply of a short fibre mat is added, followed by the PowerRibs’ 3D structure. That material ‘stack’ is then heated in an oven and pressed, creating the functional part.
The materials offer up to 50% lightweighting compared to current standards, according to the company, reducing plastic use by up to 70% and the overall eco-footprint by 60%. Other claimed advantages include enhanced vibration damping.
The fine margins and exceptionalism of Formula One gave the company vital experience competing against “the pinnacle of materials”, Wacht says – carbon fibre. “The beauty is that we have, in this specific weight window, the same bending stiffness and weight as carbon,” he says.
At large carmakers, the materials face the same safety standards as more conventional options. Bcomp composites successfully passed difficult tests for seatback materials with Cupra, Wacht says. “These are harsh tests you need to pass, and we have successfully proven that we can do that with our natural fibre technologies. Same for fire resistance.”
The company announced a collaboration with SFG Composites in February to scale up production of the materials at the partner’s Dubai factory.
Growth market
Sustainability is a key aim in all applications, but available emissions reductions depend on the previously-used material. The carbonising process needed to make carbon fibre, for example, requires temperatures of 1,000-3,000ºC. Bcomp’s materials do not require those high temperatures, cutting the overall energy requirement.
By replacing fossil-fuel based plastics and supporting end-of-life recycling of components, the company hopes it can provide a greener alternative for carmakers – but using natural materials does not make them inherently sustainable, as demonstrated by the monoculture crops grown for biofuel production. “When someone claims ‘OK, we have a bio-based material, and because it's bio-based, it's sustainable’, that is something that typically doesn't work,” says Wacht.
Bcomp decided to use flax, which is also used to make linen and linseed oil, because of the “very old and mature” supply chain, mainly based in France, which is used to providing extremely high volumes. The materials do not rely on expanding production or finding new access to a particular type of plant, Wacht adds.
Despite the many claimed advantages, widespread use of natural fibre composites is likely to take some time. “The automotive industry is a huge vehicle that operates on very different timelines than most people in the day-to-day world would think about,” Wacht says. “There is a certain delay between having a technology ready and having a technology visible in the car.”
In motorsports, he says, Bcomp’s fastest project between an initial phone call and a race was just two weeks, including engineering, manufacture, shipping and installation of parts. A similar process can take three to five years in the automotive industry.
“The other case is that the automotive industry is fully [geared for] perfection, risk aversion and so on,” Wacht adds. “It's an environment where introducing innovation is tricky, but we are very lucky that we have trusted partners.”
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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.