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Technology | composites and LFTs

moulding that incorporates continu- ous glass rovings into the molten polymer in the injection machine bar-

rel. However, a spokesperson for the Kalletal, Germany-based company told Injection World at the beginning of this year the development, while still ongoing, has progressed much more slowly than originally expected

long glass fibre directly into the moulding machine barrel. In the first stage of plasticisation the polymer granules are melted, then the fibres are introduced into the plasticised melt in a second homogenisation phase. The glass fibre is fed into the system via a side feeder from Stuttgart, Germany-based Coperion. This is flange-mounted to the plasticising cylinder in a similar fashion to a feeder on a twin screw extruder. The feeder is supplied with glass fibre strands cut to

the required length for the individual application using a rotary cutter manufactured by Wolfangel, a composites equipment specialist based at Ditzingen in Germany. The cutter is positioned above the side feeder and can be adjusted to deliver a range of glass fibre lengths. According to Arburg managing director of technology Herbert Kraibühler, the introduction of the 100mm long fibres into the already plasticised polymer minimises shear forces, while location of the feeder in the final third of the plasticising screw reduces the duration of shear exposure. “Good mixing is guaranteed with introduction in the final third of the barrel but the final distribution will depend on the geometry of the part,” he says. The inline system is less costly in capital terms than

current LFT-D processing systems using twin screw compounders and can also provide considerable material cost savings, according to Arburg. The company says the base plastic and glass fibre roving raw materials required are considerably less expensive to buy than ready-to-use long LFT granulate. Arburg demonstrated the system on a 400 tonne

Allrounder 820S machine producing 330g airbag housings in LFT-D PP using a two-cavity mould on a 75s cycle. Parts were removed by a vertical Multilift Select robotic system. The company says it is still developing the processing technology together with its partner SKZ and future work will include the evaluation of carbon and natural fibre LFT products, as well as integration of the numerous process elements into the Selogica control system fitted to Arburg moulding machines.

German screw and barrel manufacturer Groche

Technik said last summer that it is also working with a number of partners on a system for LFT-D injection January/February 2013 | INJECTION WORLD 21

and it is now unlikely that a working system will be available for demonstration before 2014 at the earliest.

Continuous developments While efforts to improve the performance and process- ing of LFTs continue, many applications will require levels of mechanical performance that can only be met using continuous fibre reinforcements. In October last year BASF announced a strategic alliance with Nether- lands headquartered TenCate Advanced Composites to develop and commercialise a range of thermoplastic composite materials suitable for high volume automo- tive manufacturing. The alliance will combine TenCate’s continuous thermoplastics composites manufacturing expertise with BASF’s Ultramid PA, Ultradur PBT and Ultrason PESU resin know-how. TenCate already supplies materials under the Cetex name to aerospace firms such as Boeing and Airbus and last year it announced it had qualified to supply a major automotive company. BASF estimates that continuous fibre reinforced thermoplastics have the potential to cut part weights by 30-50% compared to metal but the processing issues must be resolved. “The next major advance in light- weight automotive constructions will not be possible without a dramatic reduction in processing costs,” says Melanie Maas-Brunner, head of the engineering plastics Europe business unit of BASF. “By working together with TenCate, we intend to jointly achieve this breakthrough.”

Left: The structural core of the rear hatch on Renault’s latest Clio is moulded in PP using Styron’s Inspire LFT concentrate

Below: Magna is using an LFT from Styron to produce this integrated hood bump stop and headlamp bracket


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