Industry News

LANXESS’ PA6 Improves Barrier-effect of BMW’s Motorcycle Tanks

Published on 2020-04-20. Edited By : SpecialChem

TAGS:  Part Design & Manufacturing     Metal Replacement    

LANXESS’ Durethan BC550Z 900116 DUSXBL is used in the motorcycle tanks of BMW Motorrad’s models F 900 R and F 900 XR. The unreinforced and impact-modified polyamide 6 comfortably meets the stringent requirements of the United States Environmental Protection Agency (EPA) with regard to permeation. Furthermore, the complex geometries can be injection-molded cost-efficiently.

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

Replacing Metal Sheets with PA 6


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.

There 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.

If the wall thickness is designed accordingly, the permeation values of the monolayer solution are several times lower than the limit of 1.5 grams per square meter of inner surface per day (g/m2∙d) as required by the EPA (Environmental Protection Agency) in EPA 40 CFR.

Perfect Weld Seams

For the current BMW Motorrad tanks, two halves are injection-molded and then welded to form the tank.

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 Dr. Klaus Küsters, business development manager, LANXESS.

The welding properties of polyamide 6 are essential for reliable tank production. “This material is characterized by its excellent welding abilities. Our customers have a wide process window at their disposal to reproducibly create tight weld seams. A weld seam factor of 1 can be achieved easily,” says Frank Krause, expert in plastic welding at LANXESS.

High Crash Resistance

Another special 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. Pendulum impact tests on aged tanks, for example, do not result in leaks at -20 °C or at 60 °C. Due to its property profile, Durethan BC550Z 900116 DUSXBL is also suitable for tanks for small vehicles, such as quad bikes, snowmobiles, and ride-on mowers, and for gasoline-powered garden tools, such as chainsaws and leaf blowers.

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