Tweco 251 Thermal Arc Fabricator - Manual (Page 62)

FABRICATOR 251
SERVICE 5-6 Manual No. 0-4847
FAULT CAUSE REMEDY
1. Weld beads are too
small
a. Decrease travel speed
2. Weld penetration
narrow and deep
a. Reduce current and voltage and increase
Mig torch travel speed or select a lower
penetration shielding gas.
A. Weld cracking 3. Excessive weld
stresses
a. Increase weld metal strength or revise
design
4. Excessive voltage a. Decrease voltage by reducing the
voltage selection switch.
5. Cooling rate too fast a. Slow the cooling rate by preheating part
to be welded or cool slowly.
6. Weld speed too fast a. Reduce weld speed.
1. Faulty rectifier unit a. Have an Accredited THERMAL ARC
Service Agent to test then replace the
faulty component.
2. Loose welding cable
connection.
a. Check all welding cable connections. B. Cold weld puddle
3. Low Primary Voltage a. Contact supply authority
4. Weld speed too fast a. Reduce weld speed.
1. The MIG torch has
been connected to
the wrong polarity on
the front panel.
a. 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 a. Reduce weld speed.
Table 5-3b: Welding Problems and Solutions continued