T.J. Snow

Resistance seam welders are built similar to press-type resistance welders except that the welding force is applied with two rotating copper wheels and the control adjusts the rotating speed and secondary amperage output. The resulting welds are continuous seams, overlapping spot welds, or evenly spaced roll spot welds. The machines are typically configured as circumferential (circular) or longitudinal. Although rare, there are seam welders that are convertible from circumferential to longitudinal.

Continuous sprays of water are directed from water nozzles to the welding wheels and onto the work as it passes through the welder. This is done to minimize warpage from heat as the metal passes between the wheels, overheating or discoloration of the parts and as a means of extending the life of the seam-welding wheels.