8 TROUBLESHOOTING
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© ESAB AB 2021
8.3 MMA (SMAW) welding troubleshooting
(only for Firepower MST-200)
Table 26: MMA (SMAW) metal welding troubleshooting
Type of fault
Cause
Corrective action
Welding current is varying
ARC FORCE is set at a value
that causes the welding
current to vary excessively
with the arc length.
Reduce the ARC FORCE until
welding current is reasonably
constant while prohibiting the
electrode from sticking to the
work piece when you “dig” the
electrode into the workpiece.
A gap is left by the failure of
the weld metal to fill the root of
the weld.
The welding current is too low.
Increase the welding current.
The electrode is too large for
joint.
Use a smaller diameter
electrode.
Insufficient gap.
Allow a wider gap.
Non-metallic particles are
trapped in the weld metal.
Non-metallic particles may be
trapped in undercut from
previous run.
If a bad undercut is present
clean slag out and cover with
a run from a smaller gauge
electrode.
Joint preparation is too
restricted.
Allow for adequate penetration
and room for cleaning out the
slag.
Irregular deposits allow slag to
be trapped.
If very bad, chip or grind out
irregularities.
Lack of penetration with slag
trapped beneath weld bead.
Use a smaller electrode with
sufficient current to give
adequate penetration. Use
suitable tools to remove all
slag from comers.
Rust or mill scale is preventing
full fusion.
Clean the joint before welding.
Wrong electrode for the
position in which welding is
done.
Use electrodes designed for
position in which welding is
done, otherwise proper control
of slag is difficult.
