The consumable is laid on the workpiece where a deposit is required. The tool, which supplies the welding current, is placed on top of the consumable and makes contact with the exposed contact ridge. An arc is initiated, the tool is moved steadily along the consumable, away from the arc and keeping a certain distance from it, and a weld is deposited on the workpiece (see Fig. 1).
Because of the moving contact, only a small length of the electrode heats up during welding, which means that long or large electrodes can be used without overheating. The coating on either side of the metal ridge protects the arc, whilst the coating thickness ('X' on Fig. 2) maintains a controlled arc length.
Compared with conventional welding - manual metal arc (MMA) welding, for instance - MCAW requires less operator skill and gives improved productivity through use of longer and larger consumables. MCAW is a relatively new, easy-to-use alternative method for welding, weld overlay and repair. It is easily mechanised and suitable for remote and restricted access operations.