Consumable wire resistance welding is a variant of resistance seam welding in which the electrode wheel is grooved so that a shaped copper wire can be introduced between the wheel and the work. The wire is fed continuously from a spool, passes around the electrode at welding speed, completes a length of weld and is then discharged to a scrap container. This ensures that there is always a clean, uncontaminated surface presented to the work.
The process is used primarily for welding coated steels, particularly tin-plate, to avoid coating pick-up on the wheel electrode. The method is highly reliable, and when mash seam welding tin cans, welding speeds over 70m/min can be achieved. Although the wire is a consumable and adds cost to the welding process, the copper has a high scrap return value.