Tweco 190 MIG Thermal Arc Fabricator - Manual (Page 54)

FABRICATOR 190 WELDING MACHINE
MANUAL GMAW WELDING 5-6 Manual No. 0-4838
FAULT CAUSE REMEDY
A. Weld cracking 1. Weld beads are too
small
Decrease travel speed
2. Weld penetration
narrow and deep
Reduce current and voltage and
increase Mig torch travel speed or
select a lower penetration shielding gas.
3. Excessive weld
stresses
Increase weld metal strength or revise
design
4. Excessive voltage Decrease voltage by reducing the
voltage selection switch.
5. Cooling rate too fast Slow the cooling rate by preheating part
to be welded or cool slowly.
6. Weld speed too fast Reduce weld speed.
B. Cold weld puddle. 1. Faulty rectifier unit Have an Accredited Thermal Arc Service
Agent to test then replace the faulty
component.
2. Loose welding cable
connection.
Check all welding cable connections.
3. Low Primary Voltage Contact supply authority
4. Weld speed too fast Reduce weld speed.
1. 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. C. Arc does not have a
crisp sound that
short arc exhibits
when the wirefeed
speed and voltage
are adjusted
correctly.
2. Weld speed too fast Reduce weld speed.
Table 5-1b: Welding Problems and Solutions (continued)