Mig Welding Common Problems and Solutions

The welding operator may encounter some problems during the application of the
process which are commonly limited to his work. Some of them can cause serial weld
defects which affect the weld quality. Sometimes, the prediction of the problem takes
a long time and requires a qualified personnel. Normally, the solution requires careful
evaluation of the wire feeder, the welding machine, the connections, the shielding gas
system and the welding technique. The following table indicates some problems that
may be encountered and possible solutions to these problems.
 Problem  Probable Cause  Solution
  • Wire stops feeding while welding.
Fuse blown in welding machine's   primary. 
Control circuit fuse blown. 
Welding machine' s contactor open. 
Primary line fuse blown. 
Control relay defective. 
Protective fuse blown. 
Wire drive rolls misaligned. 
Excess or insufficient drive roll 
Wire feeder's spindle friction too 
Excess loading of drive motor. 
Drive rolls worn; slipping. 
Drive motor burned out. 
Torch liner dirty, restricted. 
Broken or damaged torch casing or 
Torch's trigger switch defective or 
wire leads broken. 
Contact tube orifice restricted; 
burnback of electrode. 
Friction in torch liner. 
Sharp or excessive bend in torch 
cables or liner. 

Replace fuse. 

Replace fuse. 
Check for open circuit volts. 
Replace fuse. 
Replace control relay. 
Replace fuse. Find overload cause. 
Realign rolls. 

Loosen and readjust nut pressure. 

Clear restriction in drive assembly. 
Test motor; replace if necessary. 
Remove and clean with compressed 
Replace faulty part. 

Replace switch; check connections. 


Check wire passage; clean, replace 
parts as required. 
Straighten torch cables and replace 

  • Electrode wire feeds but is not energized.

Primary line fuse blown. 
Contactor plug not tight in socket. 
Contactor control leads broken. 
Remote - standard switch defective or 
in wrong position. 
Primary contactor coil or points 
Loose cable connection. 
Poor workpiece connection. 

Wire-feeder contactor plug not 
properly seated. 
Wire-feeder contact relay defective.

Replace line fuse. 
Tighten plug in receptacle. 
Repair or replace. 
Repair or replace; position correctly. 

Repair or replace. 

Tighten if loose; clean work of paint, 
rust, etc. 
Tighten plug in receptacle. 

Repair or replace. 

  • Wire feed motor operates but wire does not feed.
Insufficient drive roll pressure. 
Incorrect wire feed rolls. 
Excessive pressure on wire spool 
Restriction in the conduit liner or 
Incorrect liner or contact tube.

Match feed rolls to wire size and type. 
Decrease brake pressure. 

Check liner and contact tip. Clean 
and/or replace. 
Check and replace with correct size. 

  • Irregular wire feed and burnback.

Power circuit fluctuations. 
Polarity wrong. 

Insufficient drive roll pressure. 
Contact tube plugged or worn. 
Kinked electrode wire. 
Coiled torch cable. 

Conduit liner dirty or worn. 
Conduit too long.

Check line voltage. 
Check polarity; reverse leads if 
Clean or replace. 
Cut out,  replace spool. 
Straighten cables, hang the wire- 
Clean or replace. 
Shorten or use push-pull drive system.
  • Electrode wire wraps around drive roll (birdnesting)

Excessive feed roll pressure. 
Incorrect conduit liner or contact tip. 

Misaligned drive rolls or wire guides. 
Restriction in torch or torch cable.

 Match liner and contact tip to electrode 
 Check and align properly. 
 Remove restriction.
  • Difficult arc starting or unstable arc.

Wrong polarity. 

Poor work lead connection. 
Cable connections are loose. 
Weld joint area dirty.

  Check polarity; reverse leads if 
  Secure work lead connection. 
  Tighten connections. 
  Clean to remove scale, rust, etc. 
  • Wire feeds but no gas flows.

Failure of gas valve solenoid. 
Loose or broken wires to gas valve 
Gas cylinder is empty. 

Gas cylinder valve closed. 
Flow meter not adjusted. 

Restriction in gas line or nozzle. 

Check and repair if necessary. 

Replace and purge lines before 
Open the valve. 
Adjust to give flow specified in the 
Check and clean. 

  • Welding tourch overheats.
Pinched or clogged coolant line. 
Low coolant level in pump reservoir. 
Water pump not functioning correctly. 
Excessive amperage for torch. 
Check and correct. 
Check and add coolant as necessary. 
Check and repair or replace. 
Reduce amperage or changed to 
higher capacity torch.
  • Excessive spatter while welding.
Excessive gas flow rates. 
Insufficient gas flow. 
Too much arc voltage. 
Insufficient slope or inductance (for 
short circuiting transfer). 
Contact tube recessed too far in 
Improper electrode wire. 
Electrode position or welding 
technique are wrong. 
Reduce flow. 
Adjust gas flow rate as recommended. 
Reduce voltage as recommended. 
Increase slope or inductance setting 
as needed. 
Adjust or replace contact tube with 
longer one. 
Choose correct wire. 
Choose correct electrode position or 
proper technique as recommended. 
  • Heavily oxidized weld bead.

Air/ water leaks in torch and cables. 

Restricted shielding gas flow. 
Improper torch angle. 

Excessive nozzle to work distance. 

Air drafts. 
Excessive oxidizing gas. 
Insufficient gas flow. 
Contact tube not centered in the gas 
nozzle distance. 

Check for leaks and repair or replace 
as necessary. 
Check and clean nozzle. 
Use approximately 150 lead or trail 
Reduce. Should be approximately 1/2" 
to 3/4" (12.5-20 mm.) 
Protect weld area from drafts. 
Use correct mixed gas as required. 
Check and adjust the gas pressure. 
Center contact tube. 
  • Porosity in the weld bead.

Loose or broken wires to gas 
solenoid valve. 
Failed gas valve solenoid. 
Gas cylinder valve closed. 
Insufficient shielding gas flow. 

Leaks in gas supply lines (including 
the torch) 
Dirty base metal. 
Excessive wire feed speed. 
Moisture in the shielding gas. 
Contaminated electrode. 

Improper torch distance to workpiece. 

Wrong torch angle. 

Freezing of C02 regulator and flow 
Welding travel speed too fast. 
Too much gas flow. 

Wrong gas for the base metal or wire. 
Gas solenoid defective.

Repair or replace. 

Repair or replace 
Turn valve on. 
Check for restrictions in gas hose or 
nozzle and correct. 
Check for leaks (especially at 
connections) and repair. 
Clean to remove scale, rust, etc. 
Replace gas cylinder or supply. 
Keep wire protected while using. 
Clean wire before it enters feeder. 
Use correct distance as 
Use correct torch angle and welding 
Install gas heater before regulator. 

Use proper travel speed. 
Set regulator valve for proper 
pressure, control to flow meter. 
Choose proper gas as recommended. 

  • Electrode wire stubs into the workpiece
Excessive wire feed speed. 
Arc voltage too low. 
Excessive slope set on machine (for short circuiting transfer).
Reduce speed. 
Increase voltage. 
Reset to reduce slope.
  • Welding Cables overheating.

Cables are too small or too long. 

Cable connections loose.

Check current cables reguirements, replace or shorten if necessary.