Laser pretreatment of CFRP - Influence of laser energy denstiy and process strategy on the ablation behavour of the matrix
Adhesive joining of carbon fiber reinforced plastics requires pretreatment of the surfaces to be joined. By means of laser radiation the surface can be cleaned of contamination. At the same time an exposure of the fibers can be realized and a chemical activation can be achieved highly automated. The current research shows that laser sources in the wavelength range of 250-355 nm and >2600 nm are suitable for removal of the matrix layer with minimal damage and ablation of the carbon fibers. Cost-effective laser sources with high available laser power in the near-infrared (NIR) wavelength range of 1000-1100 nm have a high transmission in the CFRP matrix, whereby the ablation of the matrix is difficult. The ablation behavior of the NIR laser radiation on the matrix layer was extensively investigated. In addition to the laser process strategy, the laser energy density was varied. It can be revealed that the machining directions with identical laser energy input through the laser relative to the top have a different ablation behavior. This correlation can be seen repeatedly with increasing energy input. Furthermore, a different removal behavior of the CFRP matrix is shown depending on the process strategy. It was established a machining strategy to apply the cost-effective laser sources for the pretreatment of CFRP.