Tweco 400 MSTP Arcmaster User Manual
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9.02 MIG Welding Problems
Description
Possible Cause
Remedy
1 Undercut.
A Welding arc voltage too high.
A Reduce
WELD (V)
control or increase the wire
feed speed.
B Incorrect torch angle.
B Adjust angle.
C Excessive heat input.
C Increase the torch travel speed and/or reduce
welding current by reducing the
WELD (V)
control or reducing the wire feed speed.
2 Lack of penetration. A Welding current too low.
A Increase welding current by increasing wire
feed speed and increasing
WELD (V)
control.
B
Joint preparation too narrow or gap
too tight.
B Increase joint angle or gap.
C
Shielding
gas
incorrect.
C Change to a gas which gives
higher penetration.
3 Lack of fusion.
Voltage too low.
Increase
WELD (V)
control.
4 Excessive spatter.
A Voltage too high.
A Lower the voltage by reducing the
WELD (V)
control or increase wirespeed control.
B Voltage too low.
B Raise the voltage by increasing the
WELD (V)
control or reduce wirespeed control.
5 Irregular weld
shape.
A Incorrect voltage and current
settings. Convex, voltage too low.
Concave, voltage too high.
A Adjust voltage and current by adjusting the
WELD (V)
control and the wirespeed control.
B Wire is wandering.
B Replace contact tip.
C Incorrect shielding gas.
C Check shielding gas.
D
Insufficient
or
excessive heat input.
D Adjust the wirespeed control or the voltage
selection switches.
6 Weld cracking.
A Weld beads too small.
A Decrease travel speed.
B Weld penetration narrow and deep.
B Reduce current and voltage and increase MIG
torch travel speed or select a lower
penetration shielding gas.
C Excessive weld stresses.
C Increase weld metal strength or
revise design.
D
Excessive
voltage.
D Decrease voltage by reducing the
WELD (V)
control.
E Cooling rate too fast.
E Slow the cooling rate by preheating part to be
welded or cool slowly.
7 Cold weld puddle.
A Faulty rectifier unit.
A Have an accredited Thermal Arc Service Agent
to test then replace the faulty component.
B Loose welding cable connection.
B Check all welding cable connections.
C Low Primary Voltage.
C Contact
supply
authority.
8 Arc does not have
a crisp sound,
that short arc
exhibits, when the
wirefeed speed
and voltage are
adjusted correctly.
The MIG torch has been connected
to the wrong voltage polarity on the
front panel.
Connect the MIG torch to the positive (+)
welding terminal for solid wires and gas
shielded flux cored wires. Refer to the
electrode wire manufacturer for the
correct polarity.