Medicine bag was covered electrode metal core known as the welding cell. Welding core is generally a certain length and diameter of the wire. Welding, welding core has two effects: first, conduction welding current, arcing the electricity converted into heat, the second is the core itself is melted as a welding filler metal and the formation of the liquid base metal fusion weld. Welding electrodes, welding metal core part of the total weld metal. Therefore, chemical composition of welding core {a direct impact on the quality of the weld. Therefore, as the core electrode wire individually with the provisions of its brands and ingredients. If used for submerged arc welding, electroslag welding, gas welding, gas welding method for welding filler metal, then known as the wire.
Electrode coating is applied to the welding surface of the coating layer of the core. Coating in the welding consumables , decomposition of gas and molten slag, effect of mechanical protection, metallurgy and processing, the role of improving the process performance. Coating of the composition are: minerals (such as marble, fluorspar, etc.), ferroalloy and metal powder (such as ferromanganese, ilmenite, etc.), organic matter (such as wood flour, starch, etc.), chemical products (such as titanium white powder, water glass, etc.). Welding electrode coating is to determine the quality of the important factors in the welding process are the following roles:
First, enhance the stability of arc burning. Drug-free light skin is not easy to ignite arc welding. Can not be stable even if the ignition of the burn. In the electrode coating, generally contains potassium, sodium, calcium, and low ionization potential material, which can improve the stability of the arc to ensure the continuous welding process.
Second, protect the weld pool. Welding process, the air of oxygen, nitrogen and water vapor immersion weld, would adversely affect the weld. Not only the formation of pores, but also reduce the mechanical properties of the weld, and even lead to cracks. The electrode coating melted, resulting in a large number of gas enveloped the arc and weld pool, molten metal is reduced and air interactions. Weld cooling, the molten slag coating to form a layer covering the surface of the weld to protect the weld metal and to the slow cooling, reduce the possibility of porosity.
Third, to ensure that the weld oxygen to parathion impurities. Although the carbon steel welding rod  process was protected, but still it is inevitable that a small amount of oxygen into the bath, the metal and alloy oxidation, burning alloying elements, reducing the weld quality. Therefore, the electrode coating by adding a reducing agent (such as manganese, silicon, titanium, aluminum, etc.), so that the oxide reduction has entered the pool.
Fourth, additional alloying elements for the weld. Because of the high temperature arc, weld metal evaporation of alloying elements will be burning, reduce the mechanical properties of the weld. Therefore, it is necessary to weld coating of appropriate alloying elements added to make up for the burning of alloying elements, ensure or improve the mechanical properties of the weld. For some alloy welding, also needs to penetrate through the coating to the weld alloy, the weld metal and base metal composition can be close to, the mechanical properties to catch up even more than the basic metal.
Fifth, improve welding productivity, reduce splash. Electrodes are made leather medicine increase decrease droplet splash effect. Coated Electrode slightly below the melting point solder core solder, but the center of arc welding in the core area, high temperature, so the first core solder melting, melting a little bit later coating. Thus, in the electrode ends to form a short section of medicine leather tube, with the role of Arc force, the droplets hitting the pool on the straight, make it conducive to overhead position welding and vertical welding. In addition, the core coated with solder coating, the arc heat is more concentrated. Also, due to reduced metal loss caused by the splash and improve the deposition coefficient, also improved welding productivity. In addition, the welding process will also reduce the amount of dust.