The butt-welding by steel electric melting, without adding welding alloys or additional chemical products, is a widely tested process advantageous both from technological and economical point of view if compared with any other process. After arranging the four setting values of the butt-welder, according to the width and thickness of the band, the operation is executed as follows: butt the ends to join; position the blade between the clamps; push on the automatic welding button; a few seconds of tempering; clip the welding bead.