Mig (Gmaw/Fcaw) Welding Troubleshooting - ESAB Firepower MST-200 Instruction Manual

8 TROUBLESHOOTING
Type of fault
No gas flow in MIG mode.
Gas flow continues after the
trigger switch has been
released (MIG mode).
Power indicator will not
illuminate and welding arc
cannot be established.
TIG electrode melts when
arc is struck.
Arc flutters during TIG
welding.
8.2

MIG (GMAW/FCAW) welding troubleshooting

Solving problems beyond the welding terminals
The general approach to fix MIG (GMAW/FCAW) welding problems is to start at the wire spool
then work through to the MIG gun. There are two main areas where problems occur with GMAW,
porosity and inconsistent wire feed.
Porosity
When there is a gas problem, the result is usually porosity within the weld metal. Porosity always
stems from some contaminant within the molten weld pool which is in the process of escaping
during solidification of the molten metal. Contaminants range from no gas around the welding arc
to dirt on the work piece surface. Porosity can be reduced by checking the following points.
Table 23: Porosity
Type of fault
No shielding gas or wrong flow meter
settings.
No shielding gas or wrong flow gauge.
Gas leaks.
Internal gas hose in the power source.
Welding in a windy environment.
Dirty from welding, oily, painted, oxidized
or greasy plate.
Distance between the MIG gun nozzle
and the workpiece.
0463 766 001
Cause
The gas hose is damaged
Gas passage contains
impurities.
Gas regulator turned OFF.
Empty gas cylinder.
Gas valve has jammed
open due to dirt in the gas
or the gas line.
The electricity supply has
exceeded voltage limits of
the power source.
The TIG torch is connected
to the (+) VE terminal.
Tungsten electrode is too
large for the welding
current.
Corrective action
Ensure that the shielding gas cylinder is not
empty and the flow meter is correctly
adjusted to 31.75 CFH.
Ensure that the shielding gas cylinder is not
empty and the flow meter is correctly
adjusted to workshop welding: 28-35 CFH or
outdoors welding: 35-46 CFH.
Check for gas leaks between the
regulator/cylinder connection and in the gas
hose to the power source.
Ensure the hose from the solenoid valve to
the MIG gun adapter has not fractured and
that it is connected to the MIG gun adapter.
Shield the weld area from the wind or
increase the gas flow.
Clean contaminates off the workpiece.
Keep the distance between the MIG gun
nozzle and the workpiece to a minimum.
- -
70
Corrective action
Replace or repair.
Disconnect the gas hose
from the rear of the power
source and blow out dirt.
Turn ON regulator.
Replace gas cylinder.
Contact an authorised
ESAB service technician.
Ensure that the electricity
supply is within 120 V ±10%
or 230 VAC ±10%.
Connect the TIG torch to
the (-) VE terminal.
Select the correct size of
tungsten electrode. See
"TIG (L-GTAW) basic
welding technique" section.
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