MMA Welding

Welding with stick electrodes is called Manual Metal Arc (MMA)welding or Shielded Metal Arc Welding (SMAW). It is the oldest and most versatile of the various arc welding processes.

An electric arc is maintained between the end of a coated metal electrode and the work piece. As molten metal droplets from the electrode are transferred across the arc and into the molten weld puddle, they are shielded from the atmosphere by the gases produced from the decomposition of the flux coating. The molten slag floats to the top of the weld puddle where it protects the weld metal from the atmosphere during solidification. The slag must be removed after depositing each weld run.

Hundreds of different varieties of electrodes are produced, often containing alloys to add durability, strength and ductility to the weld. The process is mostly used for ferrous alloys in the structural steelwork, shipbuilding and general fabrication industries.Repair and maintenance is another important application for MMA. Despite the relative slowness of the process, because of electrode changes and slag removal, it remains one of the most flexible techniques and has advantages in areas of restricted access.

Reproduced by kind permission of ESAB Group (UK) Ltd