The energy-intensive manufacture of carbon fiber reinforced plastic tapes (CFRP tapes) makes these a comparatively expensive source material for the manufacture of aircraft and automotive components. However, an average of 30 % of these tapes are discarded, as either off-cuts or rejects in the course of conventional manufacturing processes – from the semi-finished product through finishing, tape laying and thermoforming to the finished component. No cost effective and sustainable recycling system for this unused material is yet available.
The state of North Rhine-Westphalia and the European Union are funding the "TapeZyklat" research project in which the Fraunhofer IPT is collaborating with two industrial partners to develop a recycling system for carbon fiber-reinforced plastic tapes. The aim of the project is to produce recycled tapes from material left over from the production process. In common with other producers, Lösing GmbH Schneideservice, one of the project partners, reports large quantities of scrap material left when flat tapes are cut. The re-use of this production waste will result in recycled tape, a high-quality semi-finished product. In this way, industrial tape recycling will close the value cycle and transform carbon fibers into a more sustainable material, lowering material costs at the same time. Combined with the very good mechanical properties in conjunction with lower weight and good chemical resistance, this makes CFRP tapes even more attractive to modern aircraft and automotive construction industries.
The Fraunhofer IPT will draw on its expertise in special-purpose machine building to develop and construct a recycling system that automatically produces recycled tapes from off-cuts. Various thermoplastic materials can be processed. The recycled tape consists of directional long fibers. Lösing GmbH Schneideservice is investigating how this tape can be cut to conventional processing widths. At the Fraunhofer IPT these tapes can then be processed using conventional production methods such as tape laying as well as in forming operations. The recycled tape is used in the tape laying process to produce two-dimensional laminates that are formed into demonstrator components including industrial safety helmets. These are then tested in accordance with the standards applicable to this product, demonstrating the good material properties and excellent processing characteristics of the new type of tape. This makes the material an attractive option for use in sectors such as the automotive industry or for sports equipment.
Unlike conventional CFRP tape, the tape developed in the "TapeZyklat" research project consists not of continuous fibers but of assembled pieces of tape. However, what initially sounds like a drawback actually turns out to be a major advantage: The continuous fibers used in conventional tapes mean that they have low flowability at the thermoforming stage, making it difficult to produce parts with complex shapes. However, the pieces of tape in the recycled tapes can be displaced relative to one another in the thermoforming process, enabling the material ductility to be exploited selectively in the process design phase. The project partner M.TEC Engineering GmbH simulates process and component behavior. This results not only in the availability of a more economical and more sustainable CFRP material for industry but also in additional processing advantages for thermoforming operations.