Welding gun
Component Fault symptom Cause
Type Welding gun overheats Welding gun underrated for
welding application
Liners Erratic wire feed, wire snarls up at
outlet guide
Liner of incorrect type and size
for wire in use, worn or dirty liner,
liner too long or too short
Gas distributor Inadequate gas flow, contaminated
or porous weld
Damaged or blocked distributor
Nozzle Inadequate gas cover, restricted
joint accessibility
Nozzle too large or too small,
incorrect length or shape
Contact tip Erratic feeding, wire shudder, wire
burnback, unstable arc, spatter
Incorrect size of contact tip,
incorrect contact tip to nozzle
distance for metal transfer mode,
inferior contact tip material
Nozzle insulator Arcing between contact tip and
nozzle and between nozzle and
workpiece
No nozzle insulator fitted
Regulator / flowmeter
Component Fault symptom Cause
Inlet stem No gas flow, gas leaks at regulator
body or cylinder valve
Blocked inlet stem, leaking inlet
stem to body thread, bullnose not
properly seated in cylinder case
Gas hose and fitting Leaks at connections or in the
hose, porosity in the weld
Poorly fitted “o” clips, damaged
hose, air drawn into gas stream
Shielding gas
Component Fault symptom Cause
Cylinder, MCPs No gas flow, porosity in the weld Gas cylinder closed or empty, faulty
cylinder valves
Bulk No gas flow, change in welding
conditions
Bulk tank empty, incorrectly set
mixing panel
Welding wire
Component Fault symptom Cause
Wire basket and spool Erratic wire feeding or wire
stoppages
Damaged wire basket, loose
spooling, random-wound wire
Wire Wire sticks in contact tip, erratic
feeding
Varying wire diameter, copper
flaking, surface damage
Wire Weld has excessive amount of
spatter
Wrong polarity has been selected
To Next Page