Gap width detection and process control in laser welding with filler wire

This paper describes a gap width detection and adaptive control system for butt-joint laser welding with filler wire. A scanning Laser-PSD (Position Sensitive Detector) sensing system for detecting the gap width has been developed, by which a detecting precision of 0.1mm can be obtained. Based on the detected gap width, the system calculates the appropriate wire feed speed or welding speed by considering the necessary filling metal 10% more than the required metal volume of the groove gap, and then automatically adjusts them to guarantee optimal weld bead formation. In laser welding of butt joint with the gap width varying from 0.1mm to 0.5mm, good weld bead formation is achieved under constant laser power.