New approaches for highly productive laser welding of copper materials

Abstract

Laser welding of highly conductive materials like copper is a difficult proposition, but offers a useful non-contact joining method, well geared for automation. Copper's high reflectivity at the 1 µm wavelengths has always been the barrier in the past to implement laser welding. Frequency doubled green lasers can remove this barrier and has a high potential to revolutionize the laser welding of copper materials in high volumes and for future applications. In this paper, we present new results for welding copper and copper alloys with a novel brilliant laser, emitting in the green wavelength region (up to 325 W@515 nm, 2 mm mrad). The results are compared with a state-of-the-art solid state laser, emitting in the infrared wavelength region (up to 1000 W@1030 nm, 2 mm mrad). Fundamental investigations on the absorption and energy coupling properties in the different phases of the process (heating up, heat conduction welding, deep penetration welding) were performed to learn more about process stability and process reproducibility of the welding process at copper alloys. Significant increase in process reproducibility can be demonstrated by using a green laser.