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Session Chair: Jannik Lind, University of Stuttgart, Germany
Location:Room 4 ICM
11:15am - 11:30am
3D simulation of spatial and temporal modulation in laser beam fusion cutting
Ulrich Halm1, Wolfgang Schulz1,2
1RWTH Aachen University, Germany; 2Fraunhofer Institute for Laser Technology ILT
Mean profile height and perpendicularity are, along with adherence of dross, the main quality features in laser fusion cutting of sheet metals. Research indicates that the dynamics of the thin melt film and the beam shape have a strong effect on these quality features. Recent measures to reduce the mean profile height include spatial and temporal modulation of the laser beam. A 3D simulation of the melt film dynamics is used to analyze the effect of these measures on the mean profile height and the perpendicularity of the cut surface. Insight into the temperature distribution inside the solid material allows a deeper understanding of how spatial and temporal modulation of the laser beam act on the cut surface. Furthermore, the effect of artificial additional beam sources can be analyzed. The most positive effect on the cut surface was created by a homogenous illumination of the side of the cutting front.
11:30am - 11:45am
Potential health risks due to emission of hazardous substances during outdoor laser cutting
Jürgen Walter, Christian Hennigs, Michael Hustedt, Jörg Hermsdorf, Stefan Kaierle
Laser Zentrum Hannover e.V., Germany
In contrast to well-defined industrial laser processes, there is limited knowledge regarding secondary hazards due to emission of gaseous and particulate hazardous substances during outdoor-laser applications, such as facades cleaning, pipelines repair and rescue from crashed vehicles, including hazardous-substances capturing and handling.
According to the German Clean-Air Act (TA-Luft), results of emission measurements in the exhaust air of a 2.5 kW laser-cutting process of typical automotive-multilayer structures were correlated with assessment criteria for the main hazardous components found, leading to requirements for exhaust-air cleaning. Complementary, air measurements at the operation site according to TRGS 402 were performed to evaluate whether the inhalation-exposure limits for hazardous substances released from the laser-process zone and not captured by the exhaust equipment were complied with, considering assessment criteria according to TRGS 900 and TRGS 910. The investigations showed that additional measures to reduce hazardous-substance concentrations are dispensable, if the exhaust unit is dimensioned correctly.
11:45am - 12:00pm
Striation formation at the cut edge of oxygen assisted fibre laser cutting
Handika Sandra Dewi
Luleå University of Technology, Sweden
Laser cut edges show parallel grooves features or striations. A high-quality cut edge is identified by fine striations at the cut edge. In order to gain a better understanding in striation formation at the cut edge and improve the cutting quality, striations at the cut edge and melt flow during laser cutting processes were investigated. Oxygen assisted fibre laser cutting processes were carried out on 1-mm-thick and 20-mm-thick steels at varied processing parameters and recorded using high speed imaging with borosilicate glass as replacement edge. The size of striations at the cut edge and frequency of the molten ripples were measured. The striation widths show a linear correlation with the gas pressure and cutting speed, but inverse correlation was found between striation widths and the nozzle diameter. Gas pressure is most likely the main influencing factor affecting the striation widths.
12:00pm - 12:15pm
Advanced beam shaping for high power cutting & welding
Natalia Trela-McDonald, Alex Griffiths, Gilles Diederich, Eoin Murphy
PowerPhotonic Ltd, United Kingdom
Beam shaping of light from high power fiber lasers to improve cutting or welding performance can be challenging, due to (i) high power density; (ii) short length optical train; (iii) uniformity of the shaped beam over the tolerance range of the application. We present novel approaches to the design and manufacture of high efficiency beam shaping elements for multi-mode and single-mode fiber lasers. Beam structures that are emerging as important for industrial processing – such as rings – are considered. Importantly, these designs can be manufactured with sufficient low loss and low scatter by a laser-writing freeform optical manufacturing technique.