In motorcycle tanks, a very small quantity of fuel should diffuse from tank walls. So, tank materials must have a high degree of ductility and tenacity specifically when they crash. They must render high design flexibility for complicated geometries and be economical.
BMW Motorrad’s models F 900 R and F 900 XR have tanks that have the material, Durethan BC550Z 900116 DUSXBL, by Lanxess. This material fulfills all the above needs. Polyamide 6 is unreinforced and impact-modified. It is injection-molded into two half-shells. Hot plate welding is used to weld it to the tank. Such tanks are a collaboration between BMW Motorrad and Röchling Automotive Italia S.r.l. in collaboration with LANXESS.
“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.
The Polyamide 6 monolayer solution has many advantages over other substitutes, such as integration potential and design flexibility. So, it is better than Aluminum and sheet Steel. Expensive forming, stamping, and joining can be avoided. Corrosion is out of the question. Durethan BC550Z 900116 DUSXBL exhibits lesser fuel permeation than high-density polyethylene (HDPE). Fluorination is done to decrease permeation in HDPE tanks. But, the expense and chemical aggressiveness of Fluorine makes manufactures to avoid this step.
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
Klaus Küsters
Business Development Manager, LANXESS
The Polyamide 6 monolayer solution is cheaper than multilayer systems with a highly polar layer comprising ethylene-vinyl alcohol copolymers. With proper wall thickness, the permeation values of the monolayer solution are considerably lesser than the restriction 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.
Durethan BC550Z 900116 DUSXBL, which has proved its utility in the series production of fuel tanks, was initially developed for the Blow Molding process. Motorcycles are witnessing a rising number of functions such as Automatic Stability Control. The installation space for fuel tanks is turning out to be more complicated and fragmented. In the current BMW Motorrad tanks, after injection-molding of the two halves, they are welded to form the tank. Polyamide 6 has welding properties that are conducive to reliable tank production.
Polyamide 6 also has very high impact resistance. In the event of a crash, the fuel bladder remains intact. Aged tanks can be subjected to Pendulum Impact tests without leaks from – 20 to + 60 degrees Celsius. Durethan BC550Z 900116 DUSXBL is extremely suitable for small vehicles, quad bikes, snowmobiles, ride-on mowers, gasoline-powered garden tools, chainsaws, and leaf blowers.
“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, an expert in plastic welding at LANXESS.
For more details, visit www.lanxess.com
