Tweco 300 MST Arcmaster - Manual (Page 46)

40
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.