Shielded metal arc welding (SMAW, method 111 ) – a method of arc welding using a fusible metal electrode covered with a flux coating.
How does the process of welding with covered electrodes work?
Electric current (alternating or direct current, as appropriate) produces an electric arc between the metals to be joined and the electrode.
During welding, the electrode melts, decomposes chemical compounds contained in the electrode lagging giving gaseous substances that serve as a shielding gas, and the resulting cloud protects the molten metal from oxidation and contamination caused by atmospheric components. Part of the lagging melts to form a liquid slag, covering the metal droplets dripping from the electrode.
The slag then flows to the surface of the molten metal and solidifies, thus forming a mantle on the surface to protect against further oxidation during the cooling of the weld. The slag should be removed from the cooled weld by tapping it with a special hammer. During welding, slag should be successively removed and electrode tips should be replaced with new electrodes. As a result, much of the time is taken up by additional treatments reducing the time efficiency of this method. It is assumed that only 25% of the welding time is spent on laying the weld.
Selection of the right welding technique depends on the composition of the weld metal, the electrode, the position and type of the electrode weld to be laid.
Before welding, the edges of the workpieces to be joined should be properly prepared, thoroughly cleaned from all contaminants that interfere with the proper course of the process and reduce the quality of the joint, such as: paint, grease, varnish, slag after thermal cutting., so as to ensure the proper performance of the joint at maximum welding efficiency.
Advantages of welding with outulated electrodes
Because of its versatility and simplicity, MAW is one of the most popular welding methods in the world.
It dominates the repair and maintenance industry is heavily used in industrial production and steel construction.
Low equipment prices, and the wide applicability of the method underlie its popularity, especially among amateurs and small businesses.
