Advantages and challenges of CFRP laser machining with ns-pulses

Abstract

Laser processing of carbon fibre reinforced plastics (CFRP) is gaining a significant importance in industries relying on lightweight materials due to its high grade of automatability and precise machining. The use of pulsed lasers instead of continuous wave lasers (cw) for ablation, cutting, and drilling grants some advantage regarding the process quality. Due to fast ablation with short-pulsed lasers, heat penetrates less into the material and thus generates a smaller or negligible heat affected zone in comparison to parts machined by cw-lasers with long interaction times.These short-pulse processes can be applied on curved or otherwise more complex parts, thus enabling 3D-machining of CFRP. While the processes benefit from the advantages mentioned, there are still challenges to overcome, such as longer machining time needed by pulsed laser systems and the quantity of materials to be processed. Different fibre orientations and matrix materials have varying characteristics regarding their ablation behaviour and heat conductibility.In order to characterise thermal load of the material and to avoid damage, the authors investigate the influence on matrix and fibres for different CFRP with respect to their build-up, e.g. crimped fabrics (CF) and non-crimp fabrics (NCF), and different wavelengths in the near-infrared (NIR) and ultraviolet (UV) spectrum. It is demonstrated that the heat affected zone, as a damage indicator, can be reduced to a minimum by optimising those parameters for nanosecond (ns) lasers. This investigation is validated by using polished micrograph sections and micro-computer tomography (µ-CT).Laser processing of carbon fibre reinforced plastics (CFRP) is gaining a significant importance in industries relying on lightweight materials due to its high grade of automatability and precise machining. The use of pulsed lasers instead of continuous wave lasers (cw) for ablation, cutting, and drilling grants some advantage regarding the process quality. Due to fast ablation with short-pulsed lasers, heat penetrates less into the material and thus generates a smaller or negligible heat affected zone in comparison to parts machined by cw-lasers with long interaction times.These short-pulse processes can be applied on curved or otherwise more complex parts, thus enabling 3D-machining of CFRP. While the processes benefit from the advantages mentioned, there are still challenges to overcome, such as longer machining time needed by pulsed laser systems and the quantity of materials to be processed. Different fibre orientations and matrix materials have varying characteristics regarding their ablation behavio...