Mig Welding Problems - Thermal Arc ARCMASTER 300 MST Operating Manual

9.02 MIG Welding Problems

Description
1 Undercut.
2 Lack of penetration. A Welding current too low.
3 Lack of fusion.
4 Excessive spatter.
5 Irregular weld
shape.
6 Weld cracking.
7 Cold weld puddle.
8 Arc does not have a
crisp sound, that
short arc exhibits,
when the wirefeed
speed and voltage
are adjusted
correctly.
Possible Cause
A Welding arc voltage too high.
B Incorrect torch angle.
C Excessive heat input.
B Joint preparation too narrow or
gap too tight.
C Shielding gas incorrect.
Voltage too low
A Voltage too high
B Voltage too low
A Incorrect voltage and current
settings. Convex, voltage too
low. Concave, voltage too high.
B Wire is wandering.
C Incorrect shielding gas.
D Insufficient or excessive heat
input.
A Weld beads too small
B Weld penetration narrow
and deep
C Excessive weld stresses
D Excessive voltage
E Cooling rate too fast
A Faulty rectifier unit
B Loose welding cable connection
C Low Primary Voltage
The MIG torch has been
connected to the wrong voltage
polarity on the front panel.
WELD (V)
A Reduce
feed speed.
B Adjust angle.
C Increase the torch travel speed and/or reduce
welding current by reducing the
control or reducing the wire feed speed.
A Increase welding current by increasing wire feed
speed and increasing
B Increase joint angle or gap.
C Change to a gas which gives higher penetration.
WELD (V)
Increase
A Lower the voltage by reducing the
control or increase wirespeed control.
B Raise the voltage by increasing the
control or reduce wirespeed control.
A Adjust voltage and current by adjusting the
WELD (V)
control and the wirespeed control.
B Replace contact tip
C Check shielding gas
D Adjust the wirespeed control or the voltage
selection switches.
A Decrease travel speed
B Reduce current and voltage and increase MIG
torch travel speed or select a lower penetration
shielding gas.
C Increase weld metal strength or
revise design.
D Decrease voltage by reducing the
WELD (V) control.
E Slow the cooling rate by preheating part
to be welded or cool slowly.
A Have an accredited Thermal Arc Service Agent
to test then replace the faulty component.
B Check all welding cable connections.
C Contact supply authority
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.
40
Remedy
control or increase the wire
WELD (V)
WELD (V)
control.
control.
WELD (V)
WELD (V)