EXPERIMENTAL ANALYSIS OF DROPLET-GAS INTERACTION DURING GMAW PROCESS

Quality of GMAW is closely related to the behavior of the droplet from its detachment from the wire to its impingement to the weld pool. In the present research, an experimental methodology based on high-speed imaging and contour detection was developed. The images are synchronized with the current and arc voltage process. The automatic detection of contour allows to track the shape for each image and to appreciate the evolution of the liquid metal for each droplet. The methodology is then applied for a set of welding parameters and two different gases (100% Argon and 92% Argon-8%CO2), in order to see how the metal transfer is modified. The profile detection allows seeing and measuring the influence of gas on the metal liquid droplet detachment and free flight motion for each period. Temperature and surface tension of the liquid metal with its interaction with the plasma are first measured and then these quantities are applied to explain some mechanisms induced in Pulsed GMAW.