The materials of motorcycle fuel tanks need to meet strict requirements. For example, only a very small amount of fuel can diffuse through the tank wall. These materials, especially in the event of a collision, need to exhibit a high level of toughness and ductility. They also need to provide a high degree of design flexibility for complex tank geometries and should be cost-effective.
BMW Motorrad's F 900 R and F 900 XR models meet all these requirements with only one material. Both types of storage tanks are manufactured by LANXESS Durethan BC550Z 900116 DUSXBL. The unreinforced and impact-modified polyamide 6 is injection molded into two half-shells, which are then welded into cans by hot plate welding. "Our materials comfortably meet the strict requirements of the US Environmental Protection Agency (EPA) for penetration. Because it is very easy to process during injection molding, even complex geometries can be produced cost-effectively. In terms of impact loads, This kind of extremely tough material can really bring out its advantages. "Dr. Klaus Küsters, Manager of Blow Molding Business Development of LANXESS High Performance Materials (HPM) business unit, explained. These fuel tanks were jointly developed by BMW Motorrad and Röchling Automotive Italia S.r.l. in cooperation with LANXESS.
Meets strict EPA restrictions
Compared to previously used storage tank materials, the single-component solution containing polyamide 6 has several advantages. Compared with metals (such as steel and aluminum), this material has much higher design flexibility and integration potential. It also does not require expensive forming, stamping and joining steps. When using polymers, there is no need to worry about corrosion. Compared with other polymers (such as high density polyethylene (HDPE)), Durethan BC550Z 900116 DUSXBL has significantly lower fuel penetration. Although fluorination can further reduce penetration in HDPE tanks, it is advantageous to avoid this additional manufacturing step due to the cost involved and chemically aggressive fluorine.
A one-component solution with polyamide 6 is much cheaper than a combination of multilayer materials containing a highly polar permeation barrier usually made from ethylene-vinyl alcohol copolymers.
If designed according to the corresponding wall thickness, the permeation value of the single-component solution is several times lower than the limit of 1.5 grams per day (g / m2.d) per square meter of inner surface required by EPA 40 CFR.
Perfect weld
Durethan BC550Z 900116 DUSXBL was originally developed for the blow molding process and proved its value in years of mass production of fuel tanks. Due to the increased functionality of motorcycles, such as ASC (Automatic Stability Control), the installation space of fuel tanks has become more and more scattered and complicated. These geometric shapes are no longer suitable for the blow molding process. Therefore, the current BMW Motorrad fuel tank will be formed by two-half injection molding and then welding to form the fuel tank. "Through the injection molding process, not only can more complex geometries be produced, but also the wall thickness distribution can be precisely controlled, so that the CAE tools can be used to design the tank more accurately." Küsters explained. The welding performance of polyamide 6 is essential for the production of reliable fuel tanks. "This material is characterized by excellent welding capabilities. Our customers have a long processing window and can repeat tight welds. A weld factor of 1 can be easily achieved." Frank Krause, a LANXESS plastic welding expert.
High crash resistance
Another special feature of this material solution is its extremely high impact resistance. This means that even in the event of a collision, the fuel tank remains intact and no fuel escapes. For example, an aging storage tank will not cause leakage when it is subjected to a pendulum impact test at -20 ° C or 60 ° C. Due to its characteristics, Durethan BC550Z 900116 DUSXBL is also suitable for the fuel tank of small vehicles, such as four-wheel motorcycles, snowmobiles and lawn mowers; and gasoline-driven garden tools such as chainsaws and leaf blowers.