A methodology for voltage drop determination in GMA welding: arcs with short-circuiting metal transfer

¹ Federal University of Uberlândia, Faculdade de Engenharia Mecânica, Campus Santa Mônica, Zip Code: 38400-902, Uberlândia, MG, Brazil
² Paton Welding Institute, Kiev, Ukraine
³ University of Uberaba, Uberaba, MG, Brazil

Corresponding author: ascotti@mecanica.ufu.br

Received: 31 July 2005
Revised: 27 February 2006
Accepted: 21 March 2006
Published online: 24 June 2006

Abstract

The main goal of this work was the development of methodologies for determining the energetic structure of welding arcs in Gas Metal Arc Welding (GMAW), i.e., with metal transfer. The present article focuses on a methodology applied to short-circuiting transfer. This methodology is based on equations which operate with discrete instantaneous values from measurements of welding current, arc voltage, arc length and electrode + droplet length. Metal transfer images were obtained through the use of laser shadowgraphy aided by high-speed camera. Dedicate computational programs were developed for electrical and geometrical values quantifications. Synchronization between the electrical signals and the metal transfer images made possible to associate total arc voltage measured at any point of oscillograms to the arc and electrode + droplet geometrical parameters. The proposed methodology was validated by using stainless steel GMAW shielded with Ar based blends and N₂ contents ranging from 1 to 5%. The results showed that the methodology is sensitive enough for perceiving small variations in the voltage drops that compose the total arc voltage as a consequence of using different shielding blends.