The cold welder is a tool to joint non-ferrous metals and alloys without using heat, fillers or fluxes. All round wires, flat wires, sector wires and other hetero wires can be welded. This series of cold welders can weld copper wires, aluminum wires, copper-clad aluminum wires and all kinds of alloy wires. The wires after welded remain the resistivity. The tensile strength even become stronger than before.