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Technology | composites and LFTs

tee to continually optimise the process and gradually adapt it to the requirements of mass production.” Meanwhile, BASF announced last autumn it was working with specialist composites manufacturer SGL Group to develop a carbon fi bre reinforced composite based on reactive polyamides. BASF will provide the special low viscosity highly reactive caprolactam formulations required for T-RTM processing of polyamide, while SGL Group will develop the carbon fi bre surface treatments required to achieve a good bond between the fi bre and the matrix.

governed by the drapability of the fabrics.” The prototype process involves fi rst making a composite preform. A beam robot picks up the individual layers of pre-cut glass fabric reinforcement, transfers them to a binder spraying

station, then places them onto a heated core to create a multilayer reinforcement

insert. A second robot – an Engel multi-axis type – then collects the insert and places it into the reaction mould where it is impregnated with the

reactive ε-caprolactam mixture and polymerised. A conventional injection overmoulding process

follows to add the required reinforcing ribs and functional elements. “This step could be integrated into the manufacturing cell, making it possible to produce a carbon fi bre-reinforced thermoplastic component in a single workstep. Endless fi bre reinforced parts and especially CFK [carbon fi bre composite] parts typically are very stiff but prone to buckling. Therefore, back- moulding of ribs with conventional injection moulding is a big plus. In addition, assembly of CFK parts is much easier when functional elements like screws with dome heads are added with integrated injection moulding,” says Egger.

Egger says the demonstrated production system is

at an early stage of development and while its total cycle time of around fi ve minutes is fast compared to traditional composite technology it is too long when compared with standard automotive industry injection moulding processes. “Engel’s clear objective is to continue to raise the effi ciency of the process and achieve economically viable cycle times. Among other things, the short dwell time of caprolactam extends possibilities for reducing the cycle time,” he says. “Two projects are under way with partners who can guaran- January/February 2013 | INJECTION WORLD 25

“It is only with a custom-formulated fi nish that this optimal bonding can form and the carbon fi bres transmit their unique stiffness and strength properties fully to the part,” says Dr Hubert Jäger, SGL Group’s chief offi cer technol- ogy & innovation.

Click on the links for more information:

Left: Engel demonstrated an in-situ polymerisation technique for production of thermoplastic composite brake pedal components last year

Centre: Unidirectional thermocom- posite tape and LFT is used in this develop- ment automo- tive under- body shield, produced in Fraunhofer’s labs on a 70s cycle time

Below: Fabric

reinforcement being pre-

formed and trimmed as part of Engel’s in-situ

polymerisation manufacturing process

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