4.5.4 Multiple Wire Submerged Arc Welding
One of the great advantages of the submerged arc welding process is the ability to use multiple
electrodes fed into the same weld pool thus considerably increasing the deposition rate. Some
configurations (Figure 4.35) for multiple wire submerged arc welding are:
Parallel Electrode Welding: Also called twin wire welding, two electrode wires are connected in
parallel to the same power source. Both electrodes are fed by means of a single wire feeder and
through the same welding head. Welding current is the sum of currents for each electrode and a
single deep penetrating weld pool is obtained.
Multiple Arc Welding: Also called tandem welding, two (or more) electrodes can be connected to
individual power supplies and fed by separate drive rolls through separate contact tips. The lead
electrode in such cases is connected to a DC power source and the trailing electrode to an AC source
to reduce interaction between the magnetic fields of the two arcs. It is important to ensure that the
spacing between the arcs is not too large. The trailing arc is usually positioned close enough to the
leading arc that the slag cover does not solidify between deposits. The total current in multiple wire
welding can be as high as 2000 A, although in most applications it does not exceed 1200 A.
Series Arc Welding: Two electrodes, fed through separate guide tubes, are connected in series.
Separate sets of drive rolls and contact tips, insulated from each other, need to be employed. The
current path is from one electrode to another, through the weld pool. The weld bead has relatively
shallow penetration, making this arrangement useful for overlay welding.