Improvement of energy coupling of welding aluminium by CO2-lasers

Due to the material properties like -high reflectivity -high thermal conductivity -low ionisation energy, aluminium is weldable by CO sub 2 - Lasers only under appropriate conditions. Possibilities to increase the energy coupling will be discussed in this paper. The suitable application of assist gas is one possibility. Hereby it is necessary to accomodate the composition of the assist gas supply to the process parameters (beam intensity, focal length, welding speed, material composition and so on). With optimized parameters it is possible to weld aluminium sheets of thicknesses greater than 6 mm.