Laser Cutting of CFRP with a Fibre Guided High Power Nanosecond Laser Source – Influence of the Optical Fibre Diameter on Quality and Efficiency

For the development of a robot based laser cutting process of automotive 3D parts consisting of carbon fibre reinforced plastics (CFRP), investigations with a newly developed fibre guided nanosecond pulsed laser with an average power of P L = 1.5 kW were conducted. In order to investigate the best combination of quality and process time 2 different optical fibres were used, with diameters of d f = 400 μm and d f = 600 μm. The main differences between the two setups are the resulting focal diameter and the maximum available pulse energy up to E P = 80 mJ. In a first instance, a comparable investigation was performed with both fibres for a constant pulse overlap. For each fibre the minimum required line energy was investigated and cuts were performed, distributed over the complete parameter range of the laser source. The influences of the fibre diameter on the quality and efficiency of the cutting process are summarized and discussed.