Tweco 400 MST Arc Master - Manual (Page 30)

400MST
6
BASIC TROUBLE SHOOTING
6 – 3
3
TIG Welding Problems
Weld quality is dependent on the selection of the correct consumables, maintenance of equipment and
proper welding technique.
7 Cold weld puddle. A Faulty rectifier unit.
B Loose welding cable connection.
C Low Primary Voltage. A Have an Accredited Thermal Arc Service
Agent to test then replace the faulty
component.
B Check all welding cable connections.
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.
Description Possible Cause Remedy
Description Possible Cause Remedy
1 Excessive beard build-
up or poor penetration
or poor fusion at edges
of weld.
Welding current is too low. Increase weld current and/or faulty joint
preparation.
2 Weld bead too wide
and flat or undercut at
edges of weld or
excessive burn through.
Welding current is too high. Decrease weld current.
3 Weld bead too small or
insufficient penetration
or ripples in bead are
widely spaced apart.
Travel speed too fast. Reduce travel speed.
4 Weld bead too wide or
excessive bead build up
or excessive
penetration in butt joint.
Travel speed too slow. Increase travel speed.
5 Uneven leg length in
fillet joint.
Wrong placement of filler rod. Re-position filler rod.
6 Electrode melts when
arc is struck.
A Electrode is connected to the '+' terminal. A Connect the electrode to the '-' terminal.
7 Dirty weld pool. A Electrode contaminated through contact
with work piece or filler rod material.
B Gas contaminated with air.
A Clean the electrode by grinding off the
contaminates.
B Check gas lines for cuts and loose fitting
or change gas cylinder.
8 Electrode melts or
oxidizes when an arc is
struck.
A No gas flowing to welding region.
B Torch is clogged with dust.
C Gas hose is cut.
D Gas passage contains impurities.
E Gas regulator turned off.
F Torch valve is turned off.
G The electrode is too small for the welding
current.
A Check the gas lines for kinks or breaks
and gas cylinder contents.
B Clean torch. Replace gas hose.
D Disconnect gas hose from torch then
raise gas pressure and blow out
impurities.
E Turn on.
F Turn on.
G Increase electrode diameter or reduce
the welding current.