MMA WELDING: OPERATION & APPLICATION

MMA Welding is a fusion welding process that uses the heat generated by an electric arc to fuse metal in the joint area, the arc being struck between a covered consumable electrode and the work piece. The process consists of a welding power source that may provide either an AC, DC or DC and AC electric current. Connected to this power source is an electrode holder into which the electrode is placed. The circuit is completed with an earth return cable fixed between the power source and the work piece. When the arc is struck between the tip of the electrode and the work piece, the core wire begins to melt, and the coating provides a protective gas-and-slag covering to the weld.

As the core wire melts, the operator must maintain a constant arc length – distance between the end of the electrode and the work piece – to prevent the arc extinguishing. Parent metal in the immediate area of the arc is also melted and this combines with molten metal from the electrode to form a weld pool.

Applications

MMA welding is also used for hard facing, and for gouging, cutting and grooving of ferritic alloys. Applications for MMA Welding are many and varied:
• General fabrication
• Structural steelwork
• Power plant
• Process plant
• Pressure vessels
• Cryogenic plant
• Pipelines
• Shipbuilding
• Bridge-building
• Offshore fabrication
• Repair and maintenance in a wide variety of industries

MMA is particularly suited to site and external welding applications such as the repair of agricultural equipment.