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Quick Diagnosis: 7 Common Problems in Spot Welding Machines

Troubleshooting guide for when your spot welder "gets sick"

Before blaming the electrodes, it's important to verify that your spot welding machine is working correctly. Many problems that seem to be consumable issues actually originate in the equipment. Here we present the 7 most common problems and how to diagnose them.

1

Machine won't turn on

Symptom: No lights, no response when pressing start.

Common causes: Blown main fuse, disconnect switch open, power supply problem.

Check: Input voltage, fuses, breakers, loose connections in control panel.

2

Weld cycle won't start

Symptom: Machine turns on but doesn't execute cycle when pressing pedal/button.

Common causes: Safety interlock activated (door open, water missing), defective start switch, PLC/control problem.

3

Electrodes won't close

Symptom: Cylinder/mechanism doesn't lower to make contact with material.

Check: Compressor pressure (minimum 80 PSI typically), valve function, air leaks.

4

No weld (cycle runs but doesn't weld)

Symptom: Everything seems to work but parts don't join.

Check: Secondary continuity, SCR status, transformer cables and connections, ammeter during cycle.

5

Excessive material expulsion

Symptom: Constant spatter, molten metal flying.

Check: Cylinder pressure, welding parameters, electrode alignment, electrode face condition.

6

Electrodes stick to material

Symptom: Electrode adheres to part and lifts it when opening.

Check: Parameters vs specification, electrode face condition, hold time, RWMA electrode class.

7

Transformer saturation/overheating

Symptom: Inconsistent welds, very hot transformer, breakers trip.

Check: Cycles per minute vs equipment capacity, fans working, cooling time between cycles.

Important: This guide is for initial diagnosis. Never work on equipment with power connected. Always follow your plant's lockout/tagout procedures.

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