Utilizing Laser Power Modulation to Investigate the Transition from Heat-Conduction to Deep-Penetration Welding

In laser welding the two regimes of heat-conduction welding and deep-penetration welding are distinguished. In order to characterize these two process regimes, the shown approach uses a sinusoidal laser power modulation together with timeresolved coaxial back-reflection measurement and high-speed imaging. Thereby the lower laser power levels lead to heatconduction welding whereas the higher levels result in deep-penetration welding. By analyzing the measured signals for different modulation parameters and on different processed materials, detailed information about the threshold between the two welding regimes is gained and in addition the material-dependent performance within those regimes can be specified.