Product Code: ICA12_406

Advantages and Challenges of CFRP Laser Machining with ns-Pulses
Authors:
Hagen Dittmar, Laser Zentrum Hannover e.V.; Hannover Germany
Sven Bluemel, Laser Zentrum Hannover e.V.; Hannover Germany
Peter Jaeschke, Laser Zentrum Hannover e.V.; Hannover
Uwe Stute, Laser Zentrum Hannover e.V.; Hannover
Dietmar Kracht, Laser Zentrum Hannover e.V.; Hannover
Presented at ICALEO 2012

Laser processing of 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 (pw) 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 neglectable 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 like longer machining time needed by pulsed laser systems and the quantity of materials to be processed. Different fiber orientations and matrix materials have varying characteristics regarding their ablation behavior and temperature conductibility. In order to characterize thermal load of the material and to avoid damage, we investigate the influence on matrix and fibers for different CFRP with respect to their build-up, e.g., fabrics and non-crimp fabrics and different wavelength in the IR and UV. We demonstrate that the heat affected zone, as a damage indicator, can be reduced to a minimum by optimising those parameters for ns-lasers. This investigation is validated by using polished micrograph sections and micro-computer tomography.