CFRP components for BMW i3 and i8 produced by Benteler SGL with Cannon equipment

Benteler Automobiltechnik GmbH develops and produces ready-to-install modules, components, and parts for body, chassis, and engine. The joint venture Benteler-SGL Automotive Composites develops, produces, and markets components based on carbon fibre-reinforced polymers (CFRP) for the automotive industry. Among their numerous references stand the new BMW i8 and i3 series models that utilise a total of more than ten components manufactured by the Ried-based company in their new production plant. Cannon Deutschland, in cooperation with Cannon Ergos, has supplied the turn-key installation required for this important contract. The fully-automatic production plant supplied by Cannon to Benteler SGL includes:

• one high-pressure dosing unit ESTRIM for the epoxy resin application process, according to the LLD (Liquid Lay Down) distribution method;
• two 1,000 t presses for the fast polymerisation of parts;
• five handling robots for the manipulation of carbon fibres and finished parts;
• the whole set of electronic controls, safety devices and the storage facilities for chemicals.

The LLD distribution method used for this plant consists in deposing a liquid “ribbon” of formulated resin over the carbon fibre reinforcement. The sandwich of various layers of carbon fibres is therefore wetted with a uniform film of liquid that will impregnate its entire surface once pressed in the mould. The absence of in-mould flow of reacting resin coming from the mixing head reduces drastically the counter-pressure generated during injection, allowing for the use of low-tonnage clamping presses. This reflects into a limited investment in moulds and clamping tools and in a limited consumption of energy during each cycle, thus contributing to reduce production costs, says Cannon.

The high-pressure impingement mixing heads used for the ESTRIM technology allow for the use of fast-reacting formulations, able to generate parts which can be demoulded after only 3 min. A peculiar aspect of the supply consists in the possibility of using recycled carbon fibres, obtained from scraps generated by the preforming and trimming operations performed in the same plant or from other CFRP production units. A substantial saving in fibres cost can be achieved with the use of recycled reinforcement, as well as the solution of a major environmental and disposal problem, says Cannon.