Short Circuiting Transfer
The short circuiting transfer occurs when the welding current and the arc voltage is low. Metal is transferred from the electrode to the work only when the electrode is in contact with weld pool. Not any metal is transferred across the arc gap. The short circuiting frequency varies from 20 to 200. As the droplet on the wire tip makes short circuit with the weld pool, the current increase until the arc is reignited again. The rate of current rise during short circuiting must be properly controlled.It must be high enough to maintain a molten electrode tip until filler metal is transferred. Yet, it should not be a sudden surge because it causes spatter by disintegration of the transferring drop of the filler metal. The current increase is controlled by adjusting the inductance in the power source. The correct setting of the inductance will depend on the type of shielding gas and the welding parameters used. For short circuit transfer welding, the open circuit voltage should be low enough so that arc cannot continue under the existing welding conditions. A portion of the energy for arc maintenance is provided by the inductive storage of energy during the period of short circuiting. Short circuiting transfer offers a number of operating advantages. The small & fast freezing weld pool produced is well suited for joining thin sheets, for out of position welding and for bridging large root openings.