PRO-POINT 9085986 Mode D'emploi page 21

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MMA (MANUAL METAL ARC) 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 a slag covering over the weld
metal must be chipped away after welding.
These electrodes are identified by the wire diameter and by a series of
letters and numbers. The letters and numbers identify the metal alloy and
the intended use of the electrode.
The Metal Wire Core works as a conductor of the current that maintains the
arc. The core wire melts and is deposited into the welding pool.
The covering on a shielded metal arc welding electrode is called flux. The
flux on the electrode performs many different functions:
• producing a protective gas around the weld area.
• providing fluxing elements and deoxidizers.
• creating a protective slag coating over the weld as it cools.
• establishing arc characteristics.
• adding alloying elements.
Covered electrodes serve many purposes in addition to adding filler metal
to the molten pool. These additional functions are provided mainly by the
covering on the electrode.
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AC/DC Inverter TIG/Arc Welder 9085986
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