JOINING AND ASSEMBLY | INNOVATION
requirements of the US Environmental Protection Agency (EPA) with regard to permeation. Since it is very easy to process in injection moulding, even complex geometries can be produced cost- efficiently. And when it comes to impact loading, this extremely tough material really shows its strengths,” says Dr. Klaus Küsters, Business Development Manager Blow Molding in the High Performance Materials (HPM) business unit of Lanxess. According to Lanxess, the monolayer solution with PA 6 has several advantages over previously used tank materials. The design flexibil- ity and the integration potential of this material are significantly higher in comparison to metals, such as sheet steel and aluminium. 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 PA 6 is signifi- cantly 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 accord- ingly, the permeation values of the monolayer solution are several times lower than the limit of 1.5 g/m² of inner surface per day as required by the EPA in EPA 40 CFR. Durethan BC550Z 900116 DUSXBL was origi- nally developed for the blow moulding process and has been used in the series production of blow moulded fuel tanks for several years. Due to the increasing number of functions in motorcycles – for example, ASC (automatic stability control) – the installation space for fuel tanks is becoming increasingly fragmented and complex. These geometries are no longer suitable for the blow moulding process. For this reason, for the current BMW Motorrad tanks, two halves are injection- moulded and then welded to form the tank. “With the injection moulding process, it is not only possible to produce more complex geom- etries, but the wall thickness distribution can also be precisely controlled, which in turn facilitates a more precise tank design using CAE tools,” says Küsters. The welding properties of PA 6 are essential for reliable tank production. “This material is characterised by its excellent welding abilities. Our customers have a wide process window at
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Left: Lanxess has supplied PA6 to provide a cost-effective monolayer solution for a double-shell, welded motorcycle fuel tank
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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.
Another special feature of this material solution is its 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. Avient has developed a Bergamid laser weld-
able material for use in automotive parts, consumer goods and medical devices. With well-controlled laser transmission rates, multiple colour choices and customised performance options, this addition to the Bergamid portfolio allows manufacturers to produce high-performance parts with durable welds and smooth surfaces. The company says that polymers used for laser welding must allow a minimum 20% transmission rate for laser energy. In addition, laser absorption can be controlled by adjusting the type of pig- ments. A range of off-the-shelf and tailor-made solutions is offered to meet the required laser transmission rates for applications in a variety of markets. Commercially available in Asia only, the material solutions are formulated in PA 66 with proven laser weldability.
CLICK ON THE LINKS FOR MORE INFORMATION: �
www.lpkf.com �
www.cemaselettra.com �
www.emerson.com/branson �
www.forwardtech.com �
www.hermannultraschall.com �
www.rincoultrasonics.com �
www.lanxess.com �
www.avient.com
May 2021 | INJECTION WORLD 45
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