Electric welding is a common name for arc welding. It is a controlled welding operation which is realized by welding electrodes to connect metal parts at high temperature and melting metal parts. However, the resistance of the copper welding rod is very small, so the operation of the welder can not be controlled, so ordinary electric welders can not be welded with copper welding rods. In reality, the brazed bar is welded by oxygen welding. Oxygen welding refers to the flame generated by acetylene burning in oxygen, and its reaction expression is: Acetylene + oxygen = carbon dioxide + water. In this reaction, a large amount of heat is released, so that the temperature of the oxyacetylene flame can reach above 3000 degrees. When the metal contacts the oxyacetylene flame, it will melt quickly. With this characteristic, the welding or cutting of metals by oxyacetylene flame is usually referred to as gas welding and gas cutting.