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Fastening
& Joining Methods
Shielded-metal
Arc Welding (SMAW)
Shielded Metal Arc Welding (SMAW) or Stick
welding is a process which melts and joins
metals by heating them with an arc between
a coated metal electrode and the workpiece.
The stick electrode has an outer coating,
called flux, that assists in creating the
arc and provides the shielding gas and slag
covering to protect the weld from contamination.
The electrode core provides most of the
weld filler metal.
When the electrode is moved along the workpiece
at the correct speed the metal deposits
in a uniform layer called a bead.The Stick
Welding power source provides constant current
(CC) and may be either alternating current
(AC) or direct current (DC), depending on
the electrode being used. The best welding
characteristics are usually obtained using
DC power sources.
The power in a welding circuit is measured
in voltage and current. The voltage (Volts)
is governed by the arc length between the
electrode and the workpiece and is influenced
by electrode diameter. Current is a more
practical measureof the power in a weld
circuit and is measured in amperes (Amps).
The amperage needed to weld depends on electrode
diameter, the size and thickness of the
pieces to be welded,and the position of
the welding. Generally, a smaller electrode
and lower amperage is needed to weld a small
piece than a large piece of the same thickness.
Thin metals require less current than thick
metals, and a small electrode requires less
amperage than a large one.
It is preferable to weld on work in the
flat or horizontal position. However, when
forced to weld in vertical or overheadpositions
it is helpful to reduce the amperage from
that used when welding horizontally. Best
welding results areachieved by maintaining
a short arc, moving the electrode at a uniform
speed, and feeding the electrode downward
at a constant speed as it melts.
This is the most commonly utilized form
of arc welding.
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