Complex Automotive Structural Part Molded from Single Preform

Stephen Moore | Nov 15, 2022

Cannon Tipos has collaborated with Coriolis Composites for the fast and precise high-pressure resin transfer molding (HP-RTM) of a near- to net-shape dry preform. The part is manufactured with Coriolis’ patented automated fiber-placement (AFP) technology.

Coriolis Composites is a world leader in the supply of AFP robotic equipment and machines, which enable the laying of continuous or discontinuous fibers with minimum material wastage, in various orientations, even for complex geometrical surfaces. It has developed an exclusive process to make dry-fiber functionalized preforms of composite parts for a range of industrial sectors, notably aerospace and automotive.

"It is only in the last decade that advanced, cost-effective engineered preform technologies have emerged, replacing the need for labor-intensive and accurate alignment of several preforms in an HP-RTM mold," said Andrea Castelnovo, Technology and R&D Manager at Cannon Tipos. "The innovative near- to net-shape dry preform developed through Coriolis’ AFP process and our steel mold, polished to a mirror finish, and high-pressure dosing machines and injection equipment helped realize a complex body-in-white structural part for local reinforcement using a single preform in a fast and easy process with high productivity and sustainable costs."

The AFP 2D dry preform is composed of an optimized fiber orientation of unidirectional (UD) non-woven carbon fiber layers (280 g/m2 ply) with a 55% fiber volume fraction (FVF), achieving superior mechanical properties in the final part and incorporating proprietary binding technology compatible with a fast-cure epoxy resin system. Preform functionalization improves formability, permeability, and trimming (via 3D waterjet) to obtain a net-shape contour and reduce overall scrap by 50%.

The 2D preform is laid in 30 seconds in a tool that is then heated in an oven to form it into a 3D shape in a cycle time of one minute, according to Castelnovo. "The actual HP-RTM process cycle time is three minutes, and we are looking at a production run of 250,000 parts," he adds.

Cannon Tipos engineered the steel mold to withstand up to 120 bar (1,740 psi) of pressure, thereby avoiding microporosity. A constant temperature is maintained to within 2°C to ensure optimal resin reaction with the hardener and minimize counterpressure during the infusion phase and maximize vacuum time to avoid washout and air bubbles. Further, the highly polished cavities fully exploit the surface aesthetics of the final molded part obtainable with Coriolis’ preform technology.

The resulting BIW local structural part for series production is undergoing qualification trials. It has a 20-second takt time — the rate needed to complete a product to meet customer demand — and displays equivalent mechanical performance when compared to incumbent [metal] solutions while offering up to 80% weight reduction.

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