2.6 Stick
(
MMA
)
Welding
One of the most common types of arc welding is
manual metal arc welding (MMA) or stick welding.
An electric current is used to strike an arc between
the base material and a consumable electrode rod
or ‘stick’. The electrode rod is made of a material
that is compatible with the base material being
welded and is covered with a flux that gives off
gaseous vapours that serve as a shielding gas
and providing a layer of slag, both of which
protect the weld area from atmospheric
contamination.
The electrode core itself acts as filler material the
residue from the flux that forms slag covering over
the weld metal must be chipped away after welding.
• The arc is initiated by momentarily touching the
electrode to the base metal.
• The heat of the arc melts the surface of the base
metal to form a molten pool at the end of the
electrode.
• The melted electrode metal is transferred across
the arc into the molten pool and becomes the
deposited weld metal.
• The deposit is covered and protected by a slag
which comes from the electrode coating.
• The arc and the immediate area are enveloped
by an atmosphere of protective gas.
atmospheric contamination.
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