Welding electrode in the metal core, will become paint (coating) uniform pressure to the carefully painted on the core welding. Different types of welding rod, welding cores are also different. Welding electrode core or metal core, in order to ensure the quality and performance of the weld, butt in the core content of the metal elements are strict rules, especially harmful impurities (eg sulfur, phosphorus, etc.) content, should be strictly limitations, better than the base metal. A direct impact on the core components welded weld metal composition and performance, so the core of the harmful elements welded to minimize the welding of carbon steel and low alloy steel welding core, are generally used as the welding of low carbon steel core, and fill plus manganese, silicon, chromium, nickel and other ingredients (see wire a national standard GB1300 77). The reason one hand, low-carbon low carbon Welding Wires steel wire plastic, wire drawing easier, on the other hand can reduce the CO content of reducing gas to reduce spatter or porosity, and increased the temperature of weld metal solidification, benefit of overhead position welding. Other major alloying elements added to ensure the comprehensive mechanical properties of the weld, while the performance of the welding process and the removal of impurities, but also a role. High alloy steel and aluminum, copper, iron and other metal materials, the core component of its copper brazing alloys  welding and welded metal addition to similar requirements, but also have control of impurities, according to process requirements often adding certain alloying elements. Electrode is coated with a drug skin used for melting arc welding electrodes, it is the core from the coating and the welding of two parts. In the front electrode coating are about 45 ° chamfer, which is to facilitate the arc. Welding in the rear there is a bare core, electrode length about 1 / 16, easy to hold and facilitate soldering conductive clamp. The diameter of welding rod welding Chung actually refers to the core diameter) is usually 2,2. 5,3. 2 or 3,4,5 or 6mm and so are several specifications used is a small 3.2 small 4 small 5 III species, its length "L" is generally between 250 ^ -450 mm.