Laser drilling of carbon fibre reinforced plastics – High quality machining for aerospace applications and yet a fast process?
In the aviation industry, a major market for carbon fibre reinforced plastics (CFRP), >34.000 drilling operations are performed throughout the assembly process of an Airbus A350 section 13/14 only. Additionally, a continuous pressure for cost and time optimization exists within the manufacturing process. The quality requirements in the aviation industry are set to a high level and drilling tools have to be changed frequently, causing considerable costs in terms of tooling and time losses. Laser processing offers benefits such as flexible, wear free cutting and so has a share in the optimization of processing costs. In this investigation a laser machine, processing strategies, process control and handling equipment adapted to high precision macro drilling and low cycle times are presented. The setup included a novel short pulsed high power laser source by TRUMPF Laser GmbH emitting at λ = 1030 nm integrated in a 5 axis machine. The lab-state laser source provides pulses at tp = 20 ns, at a maximum pulse energy of E = 100 mJ and a maximum average power of Pavg = 1.5 kW, while maintaining a very good beam quality, allowing for small focus diameters. It was shown that processing with this laser source led to competitive cycle times while no heat affected zone was observed. Orthogonal borehole sidewalls were achieved by adapted strategies on materials up to 5 mm thickness, meeting tight tolerances required in industry. The experiments included mechanical testing at coupon level and demonstration of one shot borehole and counterbore processes. The overall results revealed a promising future industrial processing option for high quality macro boreholes.