Product Code: ICA10_1904

Welding with High Brilliance Lasers and Great Power Density
Authors:
Andreas Patschger, University of Applied Science Jena; Jena Germany
Markus Franz, University of Applied Science Jena; Jena Germany
Jens Bliedtner, University of Applied Science Jena; Jena Germany
Jean-Pierre Bergmann, JENOPTIK Automatisierungstechnik GmbH Jena; Jena Germany
Presented at ICALEO 2010

The increasing demand on efficient and powerful lasers let the market for fiber- and disc-lasers still grow. These systems include a high brilliance and so for the ability to realize very small foki or a long focal length.
In this research phenomenological analysis were done to figure out the correlation between small foki and welding depth. Furthermore the stability of the laser process and the resulting strength of a double steel sheet joint are investigated.
The power density in the laser beam increases when focussing gets stronger and foki turns smaller. But the flank angle will get more precipitous and therefore the Rayleigh length decreases. This could mean also a shorter welding depth. The investigations on blind welds and beam shape measurements determine a threshold of focus diameter below which the welding depth starts to decrease again.
Often there are root fusions on multi sheet joints to maximize the resulting strength. But this also can lead to weld imperfections through holes or burn-ins. This research demonstrates that a controlled reduced welding depth can also provide nearly the same strength and as benefit does not injuries the lower surface and its coating.