Effect of welding current on metal transfer in GMAW

Purpose: The paper presents findings related to the influence of welding current on metal transfer in GMAW. The main goal was to understand how droplet diameter, droplet velocity and droplet transfer rate change with the wire feed speed which determines the welding current.Design/methodology/approach: The experimental station was designed and built. A high speed video camera “Olympus i-SPEED” was used. The investigations were conducted on an automated GMAW platform. For each wire feed speed the images of metal transfer and welding parameters were recorded.Findings: Research results presented in this paper indicate that the wire feed speed (welding current) has a significant influence on droplet diameter, droplet velocity and transfer rate. The new method based on narrow band filter for imaging is much more sensitive to the changes of welding conditions and should be used as a tool for monitoring of GMAW process.Research limitations/implications: The high speed video camera is an expensive instrument and it can be used only as a laboratory tool in monitoring and optimizing of welding processes.Practical implications: The gained experience will help to determine the further directions for the research on metal transfer in GMAW and help the authors to be prepared for studying the CMT welding process. This methodology will be particularly attractive for welded – structures manufacturing industry because it could significantly reduce the cost of production by optimizing welding parameters.Originality/value: The new method for monitoring metal transfer based on narrow band filter does not require He-Ne laser to be placed ob the opposite of the imaging plane to generate a shadow. This method is thus more compact and easier to use. The original results of these investigations are mathematic descriptions of droplet flight trajectory and droplet velocity.