Faster with two wire electrodes metal inert-gas welding of aluminium materials

摘要

Metal active-gas welding using two wire electrodes has opened up new scope for boosting the efficiency of this version of the process. Following initial successes with simultaneous melt-off from two wire electrodes on unalloyed steel, efforts arenow being focused on transferring these results to MIG welding of aluminium materials.However, the first trials with twin-wire welding (N.B. the various versions of MAG multi-wire welding are presented in [1]) failed to deliver the expected gains in welding speed. The small length of the two arcs repeatedly led to short circuits betweenone or other wire electrode and the weld pool. This also caused arc extinction on the second wire electrode. The high current density which then occurred on the first wire electrode very quickly broke the short circuit. The result was a large amount ofweld spatter and instability of both arcs owing to the wide fluctuations in the length of the arc. Although both the spattering and the instability were reduced when the arc length was increased, this also decreased the welding speeds. For this reason, an entirely different machine concept was used in a new series of trials.