Polyamide 6 by LANXESS is a cost-effective monolayer solution for fuel tanks

BMW Motorrad’s models F 900 R and F 900 XR have been able to meet strict requirements due to a single material. The tanks in both machines are made from Durethan BC550Z 900116 DUSXBL by LANXESS.

The unreinforced and impact-modified polyamide 6 is injection-molded into two half-shells, which are then welded to form a tank by means of hot plate welding.

The tanks are a joint development of BMW Motorrad and Röchling Automotive Italia S.r.l. in collaboration with LANXESS.

The monolayer solution with polyamide 6 has several advantages over previously used tank materials. The design flexibility and the integration potential of this material are significantly higher in comparison to metals, such as sheet steel and aluminum. 

here is also no need for costly forming, stamping, and joining steps. Corrosion is also not a factor when polymers are used. 

Durethan BC550Z 900116 DUSXBL has significantly lower fuel permeation compared to other polymers, such as high density polyethylene (HDPE). Although fluorination can further reduce permeation in HDPE tanks, it is advantageous to avoid this additional manufacturing step due to the costs involved and the chemically aggressive fluorine.

The monolayer solution with polyamide 6 is significantly less expensive than multi-layer systems that contain a highly polar layer, usually made of ethylene vinyl alcohol copolymers, as a permeation barrier. 

“Our material comfortably meets the stringent requirements of the United States Environmental Protection Agency (EPA) with regard to permeation. Since it is very easy to process in injection molding, even complex geometries can be produced cost-efficiently. And when it comes to impact loading, this extremely tough material really shows its strengths,” explains Dr. Klaus Küsters, Business Development Manager Blow Molding in the High Performance Materials (HPM) business unit of LANXESS.

“With the injection molding process, it is not only possible to produce more complex geometries, the wall thickness distribution can also be precisely controlled, which in turn facilitates a more precise tank design using CAE tools,” explains Küsters. The welding properties of polyamide 6 are essential for reliable tank production.

Another feature of this material solution is its very high impact resistance. This means that the fuel bladder remains intact and no fuel escapes even in the event of a crash.