Laser Welding Machine Troubleshooting: Causes & Fixes

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Problems on this page:

Porosity in the weld Lack of penetration Weld seam off the joint Spatter and surface defects Laser source alarms Safety enclosure or interlock faults Cracking in the weld Fume extraction poor

Porosity in the weld

Hits OEE: Quality

Symptoms: Welds show pores in X-ray, sectioning or leak tests.

Shielding gas coverage poor

Check the gas flow, the nozzle condition and the nozzle distance to the part.

Contamination on the joint

Check the part cleaning; oil and coatings outgas in the weld.

Keyhole unstable from the wrong power or speed

Compare the power and speed with the approved weld schedule.

Zinc or coatings in the joint without a vent gap

Check the joint design for coated parts.

Prevention: Welds sectioned or leak tested at the frequency the quality plan sets.

Lack of penetration

Hits OEE: Quality

Symptoms: Welds do not penetrate fully and fail strength tests.

Laser power at the part lower than set

Measure the power at the work piece with a power meter.

Protective window dirty

Check and replace the protective cover glass in the optics.

Focus position wrong

Check the focus position against the weld schedule.

Joint gap too wide

Check the part fit-up and the clamping.

Prevention: Penetration checked by sectioning samples.

Weld seam off the joint

Hits OEE: Quality

Symptoms: The seam misses the joint line on some parts.

Fixture worn or parts not located

Check the fixture locators and clamps.

Seam tracking or vision system not calibrated

Calibrate the seam tracking against a reference part.

Robot or axis position drifted

Check the tool centre point and axis calibration.

Part variation from the previous step

Check the parts from the previous operation.

Prevention: Seam position checked on the first part and at set intervals.

Spatter and surface defects

Hits OEE: Quality

Symptoms: Welds show spatter, undercut or humping along the seam.

Speed and power not matched

Compare the speed and power with the approved weld schedule for that joint.

Focus too deep or too shallow

Check the focus position with the method the maker sets.

Gas flow too high, disturbing the melt pool

Reduce the gas flow to the schedule value and check the nozzle angle.

Optics contaminated, spreading the beam

Check and replace the protective cover glass.

Prevention: Weld appearance checked on samples each shift.

Laser source alarms

Hits OEE: Availability

Symptoms: The laser stops with a source, power or temperature alarm.

Chiller not cooling the source or optics

Check the chiller temperature, flow and water quality.

Fibre or optics damaged

Have the beam delivery checked by qualified staff.

Power supply fault

Check the alarm code with the maker.

Back reflection from reflective material

Check the process settings for reflective metals.

Prevention: Source alarms recorded and reviewed with the maker.

Safety enclosure or interlock faults

Hits OEE: Availability

Symptoms: The machine will not fire because of a door, curtain or interlock fault.

Door not closed or switch misaligned

Close the door and check the interlock switch; the laser must never run with the enclosure open.

Laser safety window damaged

Replace a scratched or cracked viewing window with one rated for the laser wavelength.

Light curtain fault

Check the light curtain alignment and clean its lenses.

Safety relay fault

Have the safety circuit and its relay tested by qualified staff.

Prevention: Interlocks tested on a fixed schedule.

Cracking in the weld

Hits OEE: Quality

Symptoms: Hot cracks appear along or across the weld, often at the end of the seam.

Alloy prone to hot cracking

Check the material certificates against the alloy the weld schedule was approved for.

Weld cooling too fast

Check whether a ramp-down at the end of the seam is set in the program.

Joint held under high restraint

Check the clamping so the part can shrink as it cools.

Filler wire missing or of the wrong grade

Check the wire grade where the schedule calls for filler.

Prevention: Welds checked for cracks on samples each shift.

Fume extraction poor

Hits OEE: Availability

Symptoms: Fume builds up inside the enclosure, clouds the optics and reaches the operator area.

Extraction filter full

Change the filter when its pressure drop reaches the maker limit.

Extraction hood too far from the weld

Move the hood or nozzle close to the weld point.

Extraction fan weak

Check the fan, its belt and the airflow.

Duct leaks or blockages

Inspect the ducting and repair leaks.

Prevention: Extraction airflow checked weekly.

Guidance only. Always follow lockout/tagout and your site's safe-work procedures, and verify against OEM manuals before acting.

Related equipment guides: welding · laser cutter · industrial robot · chiller · spot welder · leak tester

Stop the same fault coming back

Recurring laser welding machine stops usually trace to a cause you cannot see by hand. The partner we recommend is Fabrico: it tracks OEE and downtime live from PLCs, IoT sensors or AI cameras; where cameras are fitted, the video of a stop sits next to its machine data so the cause can be reviewed; and a technician opens the work order from the stop in the same system. Data is hosted in the AWS EU region, and Fabrico and the company behind it hold ISO/IEC 27001, ISO/IEC 20000-1 and ISO 9001.

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Methods that cut recurring stops: the six big losses · root cause analysis · preventive vs predictive maintenance · TPM · SMED & changeover