Karim Chouf

New nozzle for high power CO2 laser welding with Argon as shielding gas

It is known that Helium is the most efficient shielding gas for the high power CO2 laser welding process. The high ionization potential of helium limits the ionization 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. The higher the power density above the metallic plasma plume is, the easier the parasitic plasma formation in the shielding gas will be.this paper, we present a solution to weld with a high power CO2 laser beam and 100% Argon or other free Helium gases. The solution is suitable up to 12kW CO2 and a 100% Argon flow rates of 35l/min. The results obtained with Argon shielding gas have the same quality of the traditional ones obtained with Helium.It is known that Helium is the most efficient shielding gas for the high power CO2 laser welding process. The high ionization potential of helium limits the ionization 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. The higher the power density above the metallic plasma plume is, the easier the parasitic plasma formation in the shielding gas will be.this paper, we present a solution to weld with a high power CO2 laser beam and 100% Arg...