Tweco 181i Thermal Arc Fabricator - Manual (Page 66)

Fabricator 181i
BASIC WELDING GUIDE 4-8 Manual 0-5191
Basic MIG Welding Troubleshooting
FAULT CAUSE REMEDY
1 Undercut A Welding arc voltage too high. A Decrease voltage or increase the wire feed
speed.
B Incorrect MIG Gun angle B Adjust angle.
C Excessive heat input C Increase the MIG Gun travel speed and/or
decrease welding current by decreasing the
voltage or decreasing the wire feed speed.
2 Lack of penetration A Welding current too low A Increase welding current by increasing wire
feed speed and increasing voltage.
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 voltage.
4 Excessive spatter A Voltage too high A Decrease voltage or increase the wirespeed
control.
B Voltage too low B Increase the voltage or decrease wirespeed.
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
voltage control and the wirespeed control.
B Wire is wandering. B Replace Velocity contact tip.
C Incorrect shielding gas C Check shielding gas.
D Insufficient or excessive heat
input
D Adjust the wirespeed control or the voltage
control.
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 Gun
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.
E Cooling rate too fast E Slow the cooling rate by preheating part to be
welded or cool slowly.
7 Cold weld puddle A Loose welding cable connection. A Check all welding cable connections.
B Low primary voltage
B Contact supply authority.
C Fault in power source C Have an Accredited Thermal Arc Service Provider
to test then replace the faulty component.
8 Arc does not have a crisp
sound that short arc ex-
hibits when the wirefeed
speed and voltage are
adjusted correctly.
The MIG Gun has been con-
nected to the wrong voltage
polarity on the front panel.
Connect the MIG Gun to the positive (+) welding
terminal for solid wires and gas shielded
flux cored wires. Refer to the electrode wire
manufacturer for the correct polarity.
9 Poor weld result from
setup chart parameters
Contact tip has arc marks in the
bore causing excessive drag on
the wire
Replace the contact tip with only a Genuine
Tweco Velocity contact tip.
Table 4-4: MIG Welding Problems