Monitoring of high power diode laser sheet metal welding

Welding thin sheet metal in the 1 mm range with high power diode lasers closes the feed rate gap between conventional techniques like TIG- or plasma-welding and CO2- or Nd:YAG-laser welding. This was presented by Fraunhofer IWS at former ICALEO events. Applying sheet metal welding with high power diode lasers for industrial manufacturing raises the question of monitoring full penetration. Two sensor principles have been investigated concerning their suitability at welding nickel base alloy sheets in a controlled shield gas atmosphere. A special shield gas chamber for high power diode laser applications has been applied to avoid any oxidation of the weld. Optical emission spectroscopy and an infrared sensitive camera delivered promising results each. Both sensor principles are an approach for future optimized welding sensors.