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DSM and KACO develop crankshaft cover made in bio-based EcoPaXX polyamide 410 for next-gen VW diesels

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Crankshaft cover. Click to enlarge.

Royal DSM, together with its automotive component specialist partner KACO, has developed a lightweight multi-functional crankshaft cover in EcoPaXX, DSM’s bio-based polyamide 410, for the latest generation of diesel engines developed by the Volkswagen Group. EcoPaXX, a bio-based, high-performance long-chain polyamide, is made mainly from tropical castor beans.

This EcoPaXX cover incorporates integral seals in PTFE and liquid silicon rubber (LSR), as well as various metal inserts. It will be used on Volkswagen’s new MDB modular diesel engine platform, implemented across its Audi, Seat, Škoda and VW brands.

Compared with covers made in aluminum, system costs for the EcoPaXX cover are considerably lower, due in part to the use of an integrated, fully automated production cell for the component at KACO. Weight has been reduced considerably too, since the EcoPaXX grade is 45% less dense than aluminum.

The development represents a step forward in terms of sustainability, from material production to the vehicle on the road. DSM’s EcoPaXX polyamide 410 is 70% derived from renewable resources, and the polymer is certified 100% carbon neutral from cradle to gate.

Thermoplastic crankshaft covers are still uncommon, with polyamide 6 or 66 being the favored material. The very tight dimensional specification of the VW version, as well as the high loads it has to withstand, made the challenge of producing it in thermoplastic particularly severe, DSM said.

The overall performance of EcoPaXX—its very good mechanical properties at elevated temperatures, in combination with excellent toughness—make it suited for the required high performance under extreme use.

Fiber orientation, the number and position of gating points, and the design and integration of the various inserts have all been optimized to minimize warpage and ensure tight seals between the cover and the engine block and oil sump. The cover also has to resist tightening of bolts fixing it to the engine block and the sump (each of which is built to different tolerances), as well as from tools used to fix the position of the FEAD (Front End Accessory Drive) belt.

In component production, KACO uses the highly energy-efficient production cell to not only mold the crankshaft cover, but also integrate two separate seals: the first, in PTFE, is placed into the mold by a robot, and EcoPaXX is over-molded onto it; the second, in LSR, is then molded directly into the part using a 2K process. This results in reduced energy consumption during production, as well as zero material waste.

The part comes out of the injection molding cell ready to be assembled onto the engine block. No trimming is necessary at all. By taking a holistic approach to automotive part design and production, we are contributing to sustainable technological progress without any compromise on part performance or competitiveness.

—Andreas Genesius, head of project management at KACO

Finally, because the finished cover weighs so much less than an aluminium version, it helps the vehicle run more efficiently, saving fuel and reducing carbon dioxide emissions throughout its lifetime.

Genesius adds that a key to the successful launch of the crankshaft cover after an extremely short development period was the strategic joint development with key partners, including DSM, in the areas of part design, material development, process design and bonding of the different materials.

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