Porsche launches low-volume production with bio-based materials
AUTOMAKER Porsche is leveraging the benefits of organic materials in automotive manufacturing applications. The new 718 Cayman GT4 Clubsport features body parts made of natural-fibre composite materials developed in the Application Centre for Wood Fibre Research HOFZET, part of the Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut WKI, together with the Institute for Bioplastics and Biocomposites IfBB of Hannover University of Applied Sciences and Arts.
New developments in lightweight design are an absolute prerequisite for truly efficient e-cars. Until now the favoured solution here has been lightweight steels and carbon-fibre-reinforced plastics. But this solution also has its disadvantages: First of all, it entails substantial challenges in machining, repairs and recycling. Secondly, manufacturing these materials is highly energy-intensive, subtracting from the positive environmental aspect of weight reduction.
Researchers at Fraunhofer WKI thus posed the question of whether or not other fibrous materials could be used to reduce component weight, only using carbon fibres in those places where they represent a structural advantage. Natural-fibre-reinforced plastics turned out to be the answer. As components in organic composites, vegetable fibres are a sustainable alternative for lightweight vehicle bodies. The biogenic component improves the ecological impact of industrial high-performance composite materials during manufacturing, use and disposal.
Economically speaking, the use of renewable raw materials is beneficial because natural flax, hemp, wood and jute fibres are less expensive than carbon fibres and require less energy to manufacture. And there are additional advantages in industrial processing and with applications in the vehicle: The naturally grown structure of organic composites gives materials acoustic damping properties and reduces splintering, which is important in the event of a collision.
Porsche starts series production
These arguments were convincing enough to Porsche. Joining forces with Porsche Motorsport, scientists at Fraunhofer WKI first tested organic materials for series readiness under extreme conditions on a Porsche Cayman GT4 Clubsport using the mobile development laboratory of the German “Four Motors” racing team.
“The third generation of the ‘Bioconcept-Car’ has been on the race track since 2015. The tests combine the advantage of extreme stress with a vehicle that is also street-legal after modifications. The partnership with Porsche AG also enables development under the realistic conditions of an automobile manufacturer,” says Ole Hansen, project manager at the Fraunhofer WKI Application Centre for Wood Fiber Research HOFZET. “We’ve been able to continuously improve the material properties over the last four years.”
The new 718 Cayman GT4 Clubsport is the first car in series production to feature body parts made of a natural-fibre composite material. The driver and passenger doors as well as the rear wing are made using a mixture of organic fibres. And the Cayman is a real lightweight, weighing in at only 1 320kg. A factor here is the 60% weight saving resulting from the use of organic composite materials instead of steel in the doors.
The composite material consists of a thermoset polymer matrix system reinforced with organic fibres. An organic fibre mesh is used because the raw materials are readily available, it exhibits high tensile strength, and is particularly fine, homogenous and drapable, easily fitting part shapes. The ease with which it can be produced to precise dimensions facilitate machining and quality assurance, even in combination with other conventionally manufactured components.