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44
© Weldclass 2020 | E.&O.E.
11.11.3
Weld Quality Problems
Other weld problems can be reduced by checking the following points.
Troubleshooting – MIG Weld Quality
Fault
Cause
Remedy
Undercut
Figure 40
Welding arc voltage too high
Decrease voltage or increase
the wire feed speed.
Incorrect torch angle
Adjust angle.
Excessive heat input
Increase the torch travel speed
and/or
decrease
welding
current by decreasing the
voltage or decreasing the wire
feed speed.
Lack of penetration
Figure 41
Welding current too low.
Increase welding current by
increasing wire feed speed and
increasing voltage.
Joint preparation too narrow or gap
too tight.
Increase joint angle or gap.
Shielding gas incorrect.
Change to a gas which gives
higher penetration.
Lack of fusion
Figure 42
Voltage too low
Increase voltage
Excessive spatter
Figure 43
Voltage too high
Decrease voltage or increase
the Current (Wire Speed)
control/
Voltage too low.
Increase
the
voltage
or
decrease Current (Wire Speed)
Irregular weld shape
Incorrect voltage and current
settings.
Convex, voltage too low.
Concave, voltage too high.
Adjust voltage and current by
adjusting the voltage control
and the Current (Wire Speed)
control
Wire is wandering.
Replace contact tip.
Incorrect shielding gas.
Check shielding gas.
Insufficient or excessive heat input.
Adjust the Current (Wire Speed)
control or the voltage control.
Weld cracking
Figure 44
Weld bead is too small.
Decrease travel speed.
Weld penetration narrow and deep.
Reduce current and voltage and
increase MIG torch travel speed
or select a lower penetration
shielding gas.
Excessive weld stresses.
Increase weld metal strength or
revise design.
Excessive voltage.
Decrease voltage.
Cooling rate too fast.
Slow the cooling rate by
preheating part to be welded or
cool slowly.
