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2. MMA WELDING (coated electrode)
To stablish a welding electric arc, a difference of potential must be
inducted between the electrode and the workpiece.
The air between them becomes ionized and conductive, so that the
circuit is closed and an electric arc is created. The heat of the arc
partially melts the base material and the electrode to be deposited
creating a welding seam.
Arc welding is very common due to the low cost of the equipments
and the consumables used in this process.
The metal core of electrode is coated with a flux material that while
merging creates a protective atmosphere that prevents the oxidation
of the molten metal and facilitates the welding operation.
On DC power sources (rectifiers) the polarity of the electric current
affects the metal transfer mode. Typically, the electrode is connec-
ted to the positive (+), although in very thin materials it can be con-
nected to the negative (-).
Despite the favorable welding position is horizontal, this process allows its use at all positions.
MMA welding parameter chart:
Electrode Diameter
∅ 2,5 mm
∅ 3,2 mm
∅ 4,0 mm
∅ 5,0 mm
∅ 6,0 mm
∅ 8,0 mm
Welding current
40 – 125 A
105 – 250 A
75 – 185 A
140 – 305 A
210 – 430 A
275 – 450 A
Electrode holder
Coated electrode
Metal transference
Welding piece
Welding zone
Plate thickness
> 2 mm
> 3 mm
> 6 mm
> 9 mm
> 9 mm
> 9 mm
MICRO DC 162/202
Arc protection
athmosphere
Earth clamp
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