Comparative analysis of the potential of state-of-the-art lasers and new prototypic high power beam sources for cutting non-metals

At Fraunhofer IWS Dresden different, partially prototypic high power continuous wave (cw) beam sources for the remote laser processing of non-metals with galvanometric driven scanner systems are available. The emitted wavelengths of the lasers cover the range from visible light to mid-infrared. A spectroscopic analysis was performed to gain insight into processability of typical non-metal materials with single wavelengths. The wavelength depending absorption was calculated based on the measured reflectivity and transmissivity of the selected materials. Relating to those results the theoretic potential of the beam sources was verified in a comparing cutting research. The investigated work pieces are representatives of the groups of thermoplastics and thermosets, fiber reinforced polymers, glasses, natural fiber textiles and cellulosic based materials. The laser systems were divided in two groups for the investigation. To get a reference of the processability with state-of-the-art cw systems a CO2 laser with a wavelength of 10.6 µm and a solid state Yb:YAG fiber laser with 1.07 µm were used. The new prototypic beam sources were a green laser with a wavelength of 0.515 µm, a CO laser with a range of 5.3 to 5.8 µm and a CO2 laser with 9.3 µm in a power range from 1 kW to 1.5 kW. Differences in the possible focusability are caused by the wavelengths and given beam qualities. For a direct comparison those differences needed to be compensated. To get comparable intensities the spot diameter in the working distance for each laser was set to 250 µm. This allows to process the materials with almost the same intensities. Since the laser sources with the short wavelengths offer a better focusability, also experiments with the smallest possible focus diameters for the used optics were performed to get an optimized ablation result. Finally the aim of the research was to evaluate the suitability of the available beam sources for new field of application. Latest results of experimental and theoretical investigations on the remote laser processing of nonmetals with a wide range of laser wavelength will be presented and discussed.