Identification and control of metal transfer in pulsed GMAW using optical sensor

Abstract The aim of the present work was to design and develop an identification device for droplet detachments during pulsed GMAW and to assess the possibility of implementing a metal transfer control system. The developed identification device was based on a luminescence sensor and an electronic interface, capable of sensing the arc light flux. A basic control system for the pulse parameters was implemented using an A/D–D/A board for receiving signals from the sensor and sending instructions to an electronic power source and a trained neural network for the metal transfer recognition. Alternatively, the signal from the electronic interface could be directed to a microcomputer with a dedicated monitoring program. Automated pulsed welding was carried out on plain carbon steel, aluminium and stainless steel plates in the flat position. The metal transfers were recorded using a high speed camera and applying the shadowgraphy technique to validate the device performance. The results showed that the detachment device was efficient and consistent for aluminium (best results), stainless steel and low carbon welding. Moreover, the control system was capable of setting parameters that provided stable transfer at one drop per pulse rate, from welds starting at inadequate pulse parameter levels.