Welding electrode consists of two parts, the core and coating. Metal core welding electrodes are outside the paint (coating) uniform pressure applied to carefully solder core. Different types of welding, welding core is different. Welding electrode core metal core, in order to ensure the quality and performance of the weld, butt the core content of the metal element has strict rules, especially for the content of harmful impurities (such as sulfur, phosphorus, etc.), there should be strict restrictions than the base material. Electrode medicine bag was called weld metal core coated core. Welding core wire generally has a certain length and diameter. When soldering, welding core has two effects: First, conducting the welding current, the arc energy is converted into heat, the second core wire itself is used as the filler metal with a liquid molten parent metal fusion weld is formed.

Pressure applied to the surface of the coating called core solder coating. Electrode coating plays an extremely important role in the welding process. The use of drug-free light skin electrode welding, the welding process, the oxygen and nitrogen in the air will be a substantial intrusion of molten metal, the metal iron and beneficial elements carbon, silicon, manganese oxide and nitride formation of various oxides and nitrides, and remains in the weld, weld slag, or cause cracks. The melt into puddle of gas may cause a large amount of weld porosity, these factors can make the mechanical properties of the weld (strength, impact value, etc.) greatly reduced, while the weld brittle.

SMAW welding electrodes used by coating and welding core composed of two parts. When welding, a welding electrode as the one hand, and from the pilot arc current conduction effect, so that between the electrodes and the base metal in a continuous, stable arc, to provide heat necessary to melt the solder. On the other hand, and as a welding filler metal added to the weld to become a major component of the weld metal. Accordingly, the composition of the welding quality and welding, the chemical composition of the weld metal directly affect the mechanical properties and physical properties. Further, the electrode also has a great influence on the stability of the appearance quality of the weld, the welding process such as welding productivity.