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Manual metal arc welding, MMA

Joining process where a continuously supplied flux coated metal electrode creates an electric arc with the workpieces.

Illustration of Manual metal arc welding, MMA

The process

A metal rod [1] coated with an outer casing, called flux, acts as the electrode and is mounted in a welding tool [2].

A current is then applied to the electrode to create an arc [3] between the electrode and the workpiece. As a result of the high thermal energy, the electrode is melted and this creates a weld slag cover. The slag arising from the flux replaces the protective gas normally used in similar welding methods. Slag residues should be removed and finishing in the form of grinding can be applied in cases where a small weld is desired.

In comparison with other welding methods that also use arc, MMA is one of the most flexible and can weld at higher speeds.