MMA is a form of manual metal arc welding typically defined as follows:
- the basic source of heat forms an electric arc between a coated electrode and the materials to be welded in the welding process,
- the coated electrode melts forming the weld pool that cools to form a joint. The electrode consists of a core ( mainly a wire or a casted stick or a mold powders) and a coating differing by its purpose: a) electric - consists of various ionizing materials that allow more ignition power and stabilize the arc burning, b) physical - is used to protect metal before the supply of hydrogen and oxygen from the surrounding environments), c) metallurgical – doping melted metals by impurities,
- welding is performed manually (by a welder)
- the welding process starts by the electric arc ignition, it continues, without interruption, to the moment the weld is completed and the electrode is consumed. The electrode is then replaced and the process is repeated.
Advantages:
- high quality joints
- wide choice of additional materials
- highest flexibility and speed of use
- maximum availability and relatively low dependence on environmental influences
- usability and versatility in different situations and positions
- applicability to all types of joints of different size
- high reliability during the usage and low investment costs
Disadvantages:
- lower efficiency compared to MIG, MIG and ZPT
- higher incidence of errors (porosity)
- need to remove the waste
- automation and mechanization is impossible
- increased amount of harmful substances