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© Weldclass 2020 | E.&O.E.
12.9
MMA (Stick) Troubleshooting
Fault
Cause
Remedy
A gap is left by failure of the
weld metal to fill the root of
the weld.
Figure 54
Welding current too low.
Increase welding current.
Electrode too large for joint.
Use
smaller
diameter
electrode.
Insufficient gap.
Allow wider gap.
Non-metallic particles are
trapped in the weld metal.
Figure 55
Non-metallic particles may be
trapped in undercut from
previous run.
If a bad undercut is present
clean slag bout and cover with
a run from a smaller gauge
electrode.
Joint preparation 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 penetrations with slag
trapped beneath weld bead.
Use smaller electrode with
sufficient current to give
adequate penetrations. Use
suitable tools to remove all slag
from comers.
Rust or mill scale or preventing
full fusion.
Clean joint before welding.
Wrong electrode for position in
which welding is done.
Use electrodes designed for
position in which welding is
done, otherwise proper control
of slag is difficult.
A groove has been formed in
the base metal adjacent to
the top of a weld and has not
been filled by the weld metal
(undercut).
Figure 56
Welding current is too high.
Reduce welding current.
Welding arc is too long.
Reduce the length of the
welding arc.
Angle of the electrode is
incorrect.
Electrode should not be
inclined less than 45° to the
vertical face.
Joint preparation does not
allow correct electrode angle.
Allow more room for joint for
manipulation of the electrode.
Electrode too large for joint.
Use smaller gauge electrode.
Insufficient deposit time at
edge of weave.
Pause for a moment at edge of
weave to allow weld metal
build-up.
Power source is set for MIG
(GMAW) welding.
Set power source to STICK
(MMA) mode.
Portions of the weld run do Small electrodes used on heavy Use larger electrodes and
