German supplier ZSK has launched a series of innovations to an increasingly important carbon composite manufacturing technique, which, it claims, will finally overcome the cost and productivity challenges that have held back wider use of the material until now.
A development of Tailored Fibre Placement (TFP), the process is said to dramatically cuts cost, wastage and manufacturing times while offering new possibilities for improved component design, and enhancing end of life recyclability.
Unlike the conventional approach of weaving the fibres of a composite into a perpendicular arrangement then cutting the fabric to the required shape, TFP arranges the functional fibres in bundles exactly where they are most needed for structural performance and stitches them into position on a compatible base layer. This gives absolute freedom of positioning, allowing fibres to be placed in the optimum directions to carry the loads, ensures that they do not move during processing, and cuts fibre wastage to just 3% instead of the usual 30-70% on a typical automotive component. The machines are able use TFP to create 3D pre-forms which match the finished shape of a typical automotive part.
ZSK has improved the TFP method through a number of patented innovations that speed up the deposition of fibres, increase versatility and streamline the design process. Process improvements include: fast fibre laying which reduces stitching time; the fibre supply unit which doubles the deposition rate and allows simultaneous deposition of different fibres; automatic switching between different materials; the pneumatic cutting system for automated cutting of wires and fibres; and advanced design code that ensures perfect repetition of results, even controlling zig-zag stitching automatically.
"The demand for lightweight materials, to improve CO2 emissions and product performance as vehicles become heavier and more complex, has never been greater but the cost of composite manufacture has remained unaffordable in all but the most specialist niche applications," said Melanie Hoerr, ZSK manager for technical embroidery.
"Our approach using TFP breaks through that barrier by eliminating most of the manual processing and waste of conventional composite manufacture, while increasing design freedom and improving quality control."
TFP allows the composite pre-form to be conveniently produced with a mix of fibres, such as optical or metallic materials to provide specific properties such as electrical continuity or impedance. Naked antenna wires and isolated feed wires have already been combined by this method to make up RFID components.
In addition to optical and wire components, TFP can incorporate polymers commingled with carbon fibre to be melted later during moulding to form the matrix, avoiding the need for a resin filler, accelerating the production of complex parts and improving the resin-to-fibre distribution, especially in the extremities of the mould. Current difficulties with end-of-life recycling of composites could be largely overcome by choosing appropriate polymers for re-melting to simplify separation during end of life recycling.
ZSK can either provide expertise to help automotive suppliers develop prototypes and establish new TFP facilities, or can recommend one of their network of specialist manufacturers to co-develop TFP parts. It also provides ongoing manufacturing support, with both Cloud-based and off-line systems for quality control and Industry 4.0 to connect sensors and evaluate important data from the manufacturing process.