The Arc Welding Operation |
To strike the electric arc, the electrode is brought
into contact with the workpiece in a short sweeping motion and then pulled away slightly.
This initiates the melting of the workpiece and the consumable electrode, and causes droplets of the
electrode to be passed from the electrode to the weld pool. As the electrode melts, the flux covering
disintegrates, giving off vapors that protect the weld area from oxygen and other atmospheric gases.
In addition, the flux provides molten slag which covers the filler metal as it travels from the electrode
to the weld pool. Once part of the weld pool, the slag floats to the surface and protects the weld from
contamination as it solidifies. Once hardened, it must be chipped away to reveal the finished weld.
As welding progresses and the electrode melts, the welder must periodically stop welding to remove the
remaining electrode stub and insert a new electrode into the electrode holder. |
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Arc Welding Applications |
Shielded metal arc welding is one of world's most
popular welding processes, accounting for over half of all welding in some countries. Because of its
versatility and simplicity, it is particularly dominant in the maintenance and repair industry, and is
heavily used in the construction of steel structures and in industrial fabrication. Because of the
low equipment cost and wide applicability, the process is likely to remain popular, especially among
amateurs and small businesses where specialized welding processes are uneconomical and unnecessary.
The thickness of the material being welded is bounded on the low end primarily by the skill of the welder,
but rarely does it drop below 0.05 in (1.5 mm). No upper bound exists: with proper joint preparation and
use of multiple passes, materials of virtually unlimited thicknesses can be joined. |
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