Laser beam welding of copper under vacuum to extend the process limits

Abstract This study explores challenges and innovations in laser beam welding of copper, focusing on infrared lasers, beam shaping and laser welding under vacuum (LaVa). Using a Trumpf TruFiber 2000 P and a Trumpf TruDisc 6000 with BrightLine technology, the research examines copper welding under reduced ambient pressure to improve process stability and seam quality. High-speed camera observations reveal unique behaviours such as a smaller molten pool and capillary expansion under vacuum conditions. Single-mode fiber laser welding shows improved stability and a reduced number of melt ejections. Similarly, BrightLine technology shows a smaller molten pool, increased stability and greater penetration depth at lower welding velocities under vacuum. Comparisons between atmospheric and vacuum welding highlight the benefits of the latter, emphasising uniformity and minimal melt ejection. Process stability correlates with weld quality, demonstrating the benefits of vacuum conditions. The combination of vacuum and established welding techniques extends the boundaries of the process, achieving higher stability and seam quality with both types of lasers. The results show that the combination of vacuum conditions with proven welding approaches extends the process limits in copper laser welding. The potential for greater stability and improved weld quality, particularly in single-mode fiber laser welding, enables lower welding velocities and therefore greater penetration depths under vacuum conditions.