Product Code: ICAL08_M309

Weld Depth Control in Fiber Laser Welding of Thin Metal Sheets
Authors:
Jens Gedicke, Fraunhofer Institute for Lasertechnology; Aachen Germany
Alexander Olowinsky, Fraunhofer Institute for Laser Technology; Aachen Germany
Ulrich Jansen, Fraunhofer Institute for Lasertechnology; Aachen Germany
Wolfgang Schulz, Fraunhofer Institute for Laser Technology; Aachen Germany
Arnold Gillner, Fraunhofer Institute for Laser Technology; Aachen Germany
Presented at ICALEO 2008

Laser beam welding of electrical connections or sealing of casings are typical applications in the field of precision engineering. Controlling the shape of the welded connections is an important issue in this context. A common requirement is for example to achieve a specific welding depth in order not to damage functional layers or contaminate the inside of casings. The use of single mode fiber lasers in combination with scanning optics offers new opportunities regarding these needs. Applying fast beam movement for spatial power modulation, spot welds can be replaced by small circles and seam welds can be executed by superposing linear feed and modulation. Experiments revealed that depth and shape of such welds can be controlled very precisely when welding metal sheets thicker than 200 µm. Decreasing material thickness impedes this controllability with regard to thermal effects like heat accumulation. In this paper an approach for optimizing the spatial modulation parameters is introduced. In order to control depth and width of welds in metal sheets thinner than 200 µm experiments concerning variation of modulation type, welding time and focus diameter are presented. The experimental work is supported by means of simulation to optimize the mentioned parameters.