The welding metal: transfer methods With M.I.G.-M.A.G welding procedures, the method of transferring the welding metal from the wire electrode (either solid or tubular) to the weld pool depends, as well as on the electrical welding parameters, on the wire diameter, the type of power source and the gas used. Depending on these parameters, drop transfer may be by:
Immersion (short-arc, dip-transfer or short circuit)
Impulse or pulsed-arc
Immersion transfer (short-arc, dip-transfer or short circuit)
The welding metal is transferred to the weld pool in the form of drops, which are immersed in the pool itself, creating continuous short circuits.
This "short arc" transfer is characterised by the presence of current intensities of up to 200 A, by the use of thin solid wires, from 0.6 m to 1.2 mm, enabling thin welds and welding in all positions possible. This is obtained using direct current power sources.
This method is designed so that the drops of material are not transferred to the weld pool by contact but rather, due to the effect of the high current, are sprayed into the bath creating a continuous flow of material.
This feature is obtained using direct current power sources when the current used is high (greater than 200 A) and the wires have a diameter of more than 1 mm. A very fluid weld pool is generated, with sizeable penetration, which is suitable for horizontal welding of mainly medium and large thicknesses.
This procedure can only be obtained with pulsed current power sources. The pulsations actually cause small-sized drops to detach themselves and therefore the typical spray arc is obtained, even with low currents. Heat generation/contribution, pool size and penetration are similar to those achieved with the spray arc method. This procedure is most often used for materials such as aluminium or stainless steel, for which the short arc welding procedure cannot guarantee sufficiently high quality results.