Methodology for determination of parameters for welding MIG with variable polarity1

Abstract

The development of electronic power sources for welding has allowed the study of innovative processes, generally with the objective of improving the capacity of production linked to low levels of thermal support. The existing processes are based on the metal transfer mode and on the development of wave forms that improve control of the process. The metal inert gas-variable polarity pulsed process is a derivative of the conventional metal inert gas process that combines the advantages of the use of positive polarity, such as good arc stability and cathode cleaning, with those given by negative polarity, principally the high fusion rate of the electrode and low thermal support to the base metal. However, this process has only found limited use due to the scarcity of technical and scientific publications. As a result, this work sets out a proposal for a methodology to determine welding parameters in four different wave formats and varying the negative electrode rate across three levels in a way that provided arc and metal transfer stability, the evaluation of the process was carried out by filming the arc and analysing the geometric characteristics of the weld bead. The method was shown to be sufficiently efficient with satisfactory stability results.