Tweco 252i Fabricator - Manual (Page 67)

BASIC WELDING FABRICATOR 252i
Manual 0-5155 4-7 BASIC WELDING
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 Tweco Service Provider test then
replace the faulty component.
8 Arc does not have
a crisp sound that
short arc exhibits
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 param-
eters
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 4-3: MIG (GMAW /FCAW) Welding Problems
4.03 STICK (SMAW) Basic Welding
Technique
Size of Electrode
The electrode size is determined by the thickness of met-
als being joined and can also be governed by the type of
welding machine available. Small welding machines will
only provide sufficient current (amperage) to run the
smaller size electrodes.
For thin sections, it is necessary to use smaller electrodes
otherwise the arc may burn holes through the job. A little
practice will soon establish the most suitable electrode
for a given application.
Storage of Electrodes
Always store electrodes in a dry place and in their original
containers.
Electrode Polarity
Electrodes are generally connected to the ELECTRODE
HOLDER with the Electrode Holder connected positive
polarity. The WORK LEAD is connected negative polarity
and is connected to the work piece. If in doubt consult
the electrode data sheet or your nearest Accredited Tweco
Distributor.