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Technology | thermoplastic composites

of TP composite parts, Götze says, and relies on the sheet being fi xed in some areas of the mould but free to move in others. “The shaping of the sheet is done in the injection mould, and the performance of the part relies on the fi bres being in the right place. You have to focus on the whole process in a holistic way.” Full members of the LIPA project include Quadrant

Plastic Composites, Kistler Instrumente (process monitoring, sensor technology), and Krelus (its infrared heating system is used to preheat the thermoplastic prepreg before it is placed in the injection mould to facilitate forming). There are also several “support” partners, including Arburg, Borealis, DSM, KraussMaf- fei, and Kuka Roboter. Götze says his company is now working on several projects (all of which are confi dential). Depending on the project, various members of the LIPA team and partners may also be involved. One project that has already come to fruition involves Brose, a specialist in automobile door systems. At the IAA automotive exhibition in Frankfurt last September, Brose an- nounced it was “setting another benchmark for high-volume lightweight solutions” with its new door module system incorporating a TPC carrier plate. At 580 g, and with wall thicknesses down to 0.5 mm, this is 350 g lighter than conventional plastic door systems and as much as 1.2 kg lighter than standard steel alternatives, while maintaining crash safety and high functional integration. The functional carrier consists of glass fabric rein- forced PP combined with functional elements made of long glass fi ber reinforced plastic such as speaker holders and cable fasteners.

Injection equipment specialist Engel

highlights the need for perfect coordination between the material, designing and manufac- turing process, which means that companies along the value chain are challenged to cooperate with each other and combine their expertise. “It’s only interdisciplinary competence that makes fi bre compos- ite projects successful,” says Peter Egger, head of the company’s technology centre for lightweight compos- ites at its factory for large machines in St. Valentin, Austria. “Composite technologies need ‘composite’ development, and development has to occur in an alliance with others.”

At the moment, the technology centre is focusing on

the processing of composite fabrics and tapes, and also on systems that combine injection moulding with in-situ reactive processes. “At this point, it’s impossible to say which technology will be the preferred choice for January/February 2014 | INJECTION WORLD 33

specifi c applications on a regular basis in the future, but overall we believe that all these technologies have great potential,” Egger says. All were on display at K2013. Engel demonstrated

the production of the composite brake pedal on its stand, for example, using preforms heated at the machine and formed in the mould; cycle time was 54 seconds. Another production cell made use of prepregs preformed in a separate operation in an over-moulding process making small cases for handheld devices.

In-situ polymerization Engel is also looking at what can be considered as a 21st century version of resin transfer moulding, although it could be a while, if ever, before it is used in high-series automotive applications. At a symposium in 2012, it presented the fi rst prototype of a production cell for manufacturing TPC products using in-situ polymeriza- tion of caprolactam into polyamide 6 in a modifi ed injection moulding machine. The liquid components were injected over a 3D glass fabric preform that was made in a quite elaborate process within the cell. The stated advantages over preforms created by thermoforming a prepreg sheet is that here the preform is impregnated and formed at the same time, so more complicated geometries and more surface fi nishes can be obtained.

The cell, which produced a brake pedal, was

developed in a project with the Fraunhofer Institute for Chemical Technology (ICT). Since then, the process has undergone further development and, at K 2013, a production cell making a shin guard on the stand of the Institute of Plastics Processing (IKV) at RWTH Aachen University demonstrated the latest state of the art. The shin guard has an over-moulded fl exible component made of thermoplastic elastomer (TPE). The partners in the project

Below: Engel’s manufacturing cell for

production of TPC brake pedals (left), now installed at ZF


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