Firepower MST 140i, Operating Manual

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Firepower MST 140i
Manual 0-5338 4-17 BASIC WELDING GUIDE
4.05 Stick (SMAW) Welding Troubleshooting
FAULT CAUSE REMEDY
1 Welding current
varying
ARC FORCE control knob is
set at a value that causes the
welding current to vary ex-
cessively with the arc length.
Reduce the ARC FORCE control knob until welding
current is reasonably constant while prohibiting the
electrode from sticking to the work piece when you
“dig” the electrode into the workpiece.
2 A gap is left by
failure of the weld
metal to fill the
root of the weld.
A Welding current too low A Increase welding current.
B Electrode too large for joint. B Use smaller diameter electrode.
C Insufficient gap. C Allow wider gap.
3 Non-metallic par-
ticles are trapped
in the weld metal.
A Non-metallic particles may
be trapped in undercut from
previous run.
A If a bad undercut is present clean slag bout and
cover with a run from a smaller gauge electrode.
B Joint preparation too re-
stricted.
B Allow for adequate penetration and room for clean-
ing out the slag.
C Irregular deposits allow slag
to be trapped.
C If very bad, chip or grind out irregularities.
D Lack of penetration with slag
trapped beneath weld bead.
D Use smaller electrode with sufficient current to give
adequate penetration. Use suitable tools to remove
all slag from comers.
E Rust or mill scale is prevent-
ing full fusion.
E Clean joint before welding.
F Wrong electrode for position
in which welding is done.
F Use electrodes designed for position in which
welding is done, otherwise proper control of slag is
difficult.
Art # A-07711_AB
4
3
2
1
Figure 4-35: Step back Sequence
Art # A-07428_AB
Figure 4-36: Chain Intermittent Welding
Art # A-07713_AB
Figure 4-37: Staggered Intermittent Welding