SPECIAL jec composites show 2010 Combining tape laying and tape winding capabilities makes it possible to lay up precisely any angle between 0° and 90° independent from part size, lay-up rates and geodetical considerations on axially-symmetric parts. This makes the concept superior to common winding technologies. Moreover, product design can be based on load specifications and is less dependent on manufacturing requirements. This solution reduces material consumption while better utilizing the weight-saving potential of continuous fibre-reinforced thermoplastics. After improving the thermoplastic winding process, the Fraunhofer IPT successfully produced flat and contoured laminate structures using the automated laser assisted thermoplastic tape laying method. Investigations of unidirectional carbon-reinforced PA 12 and PEEK tape-laid structures clearly show the superiority of a laser heating system over open-flame and IR systems in the automated thermoplastic tape laying process. The superiority of laser heating over IR systems can be shown clearly by comparing grinding surface patterns obtained with CF/PEEK laminate structures produced at Fraunhofer IPT (Figure 2). The laser-heated laminate shows a very homogenous pattern with a low void content and hardly visible interlaminar layers. In contrast, the laminate produced with an IR heat source has a very high void content and distinct interlaminar layers. The improved structure and low void content directly result from the precise energy transfer and temperature control associated with the laser heating system. To evaluate the interlaminar shear strength of the laserassisted tape-laid components, wedge peel tests were performed on CF/PA12 and CF/PEEK specimens (Figure 3). Fig. 2: Comparison of CF/PEEK laminate qualities produced with laserand IR-assisted tape laying processes With laser-assisted tape laying, interlaminar shear strengths can be two to three times higher than those achieved with common hot gas-assisted tape laying processes. This is an impressive result considering that process optimisations for CF/PEEK prepregs are still ongoing. With the better investigated CF/PA12 prepregs, interlaminar shear strength values that are twice as high as the values for CF/PEEK have been achieved. The good performance of laser-assisted tapelaid laminates was also demonstrated by the three-point bending test performed by the Institute for Plastic Processing (IKV) in Aachen. No interlaminar fracture occurred during the examination. In summary, the laser-assisted tape laying and winding process significantly improves production speed, energy Fig. 3: Interlaminar shear strength comparison with respect to heating method and material 72 jec composites magazine / No56 April 2010