Características de fusão e potência de soldagem com a transferência MIG - CMT versus MIG convencional para alumínio 5183

Abstract

Among all arc welding processes, MIG/MAG is the one experiencing most of the innovations, originating an enormous quantity of new versions. Due to this fact, end users are faced with a great difficulty in keeping up to date with the state of the art and taking due decisions, whether in the selection of new equipment or in the selection of the correct welding mode and respective adjusting of an already available equipment. Many of the novelties come on the market with a technological appeal that not always correspond to scientific truths. Thus, this paper aims at giving a contribution to this question, addressing the CMT (Cold Metal Transfer). A study of melting characteristics is presented, providing comparisons with the conventional short-circuiting MIG/MAG process for the particular case of naval aluminum 5183. Results reveal that the apparent low electrical power of the CMT, suggested by the low average voltage and current, is not correct. Indeed for the adopted conditions it is a variant of the MG/MAG process with more power than conventional MIG/MAG, when correct power calculation procedures are made. Nevertheless CMT proves itself as good solution for aluminum root pass welds due to the adequate cadence and droplet transfer repeatability. The current and voltage cadence shows a great similarity with a rectangular pulsed wave, but inside a short-circuiting transfer range.