Product Code: ICA10_P145

New Nozzle for High Power CO2 Laser Welding with Argon as Shielding Gas
Authors:
Karim Chouf, Air Liquide - CTAS Centre technique des Applications du Soudage; saint ouen l'aumone France
Philippe Lefebvre, Air Liquide - CTAS Centre technique des Applications du Soudage; Saint Ouen L'Aumône France
Gaia Ballerini, Air Liquide - CTAS Centre technique des Applications du Soudage; Saint Ouen L'Aumône France
Francis Briand, Air Liquide - CTAS Centre technique des Applications du Soudage; Saint Ouen L'Aumône France
Presented at ICALEO 2010

It is known that Helium is the most efficient shield gas for the high power CO2 laser welding process. The high ionisation potential of helium limits the ionisation propagation from the metallic plasma plume to the shielding gas. Helium avoids the formation of parasitic plasma in the shielding gas which could absorb the incident laser beam. This phenomenon is known as Bremsstrahlung Inverse absorption. With high CO2 laser power, it is not possible to use argon as shielding gas. The formation of this parasitic plasma depends on the laser features as the power, the power density, the focused spot diameter and the focal length. Indeed, the focal length affects the opening of the focused laser beam and the power density above the metallic plasma plume resulting from the welding process. Higher will be the power density above the metallic plasma plume, easier will be the parasitic plasma formation in the shielding gas.
In this paper, we present a new nozzle solution which allows to weld using high power CO2 laser beam and argon as assisting gas. The working flow rates are around 35l/min. The resulting weld seam qualities are the same than the helium ones.