Frequently Asked Questions
Practical answers to common laser welding questions plus representative troubleshooting scenarios that show how to move from symptom to the next useful action.
Search-driven quick answers
GB 7247 laser safety
GB/T 7247.1-2024 is the current China laser product safety baseline used on this site. For laser welding cells, pair it with machine and workplace controls such as ISO 11553-1, ANSI Z136.1, OSHA workplace rules, enclosure checks, eyewear records, and fume controls.
NOHD calculator
NOHD is the Nominal Ocular Hazard Distance. It depends on wavelength, output, beam divergence, exposure assumptions, reflections, and enclosure condition. Use the result as a planning input, not as a substitute for a laser safety program.
Penetration depth calculator
Penetration-depth estimates help plan the first sample matrix. Final depth must be confirmed from sectioned samples on the actual material, optics, focus, and fixture setup.
Weld strength calculation
Weld strength calculations are screening estimates based on joint geometry, material assumptions, load path, and inspection quality. Responsible design acceptance requires the project specification and qualified engineering review.
Engineering troubleshooting patterns
These patterns show how to route a symptom into controlled checks and measured evidence.
Battery Tab Porosity Check
Situation
Apply this check when pores, unstable resistance, or internal void indications appear during battery tab trials.
What matters first
- Surface cleaning and oxide removal before welding
- Shielding coverage over the keyhole and trailing area
- Travel speed versus keyhole stability
What to Check Next
- Cross-sections for void distribution
- Gas nozzle position, flow pattern, and plume interference
- Focus offset and overlap consistency across the tab stack
Related tools:
- Energy & Heat Calculator
- Multi-Variable Analyzer
- Material Process Window Table
Stainless T-Joint Crack Check
Situation
Apply this check when centerline cracks or heat-affected brittleness show up in restrained T-joints.
What matters first
- Heat input concentration and cooling rate
- Fixture restraint and weld sequence
- Joint design access for fusion at the root
What to Check Next
- Macro sections for incomplete fusion versus solidification cracking
- Local restraint points in tooling
- Whether preheat or alternate sequencing is justified by the material and thickness
Related tools:
- Crack Risk Calculator
- Preheat Temperature Calculator
- Weld Quality Inspection Guide
Copper Absorption Setup
Situation
Apply this check when the process shows poor absorption, unstable coupling, or low penetration consistency.
What matters first
- Laser wavelength compatibility with the material surface
- Preheat strategy and reflectivity control
- Beam quality, focus placement, and part fit-up
What to Check Next
- Whether green or blue sources are required for the application
- Surface finish and oxide state before welding
- Thermal sinking from clamping or adjacent mass
Related tools:
- Penetration Depth Calculator
- Process Parameters Calculator
- Parameter Window Guide
Titanium Shielding Coverage Check
Situation
Apply this check when discoloration, oxidation, or embrittlement signs appear on the weld face or trailing area.
What matters first
- Primary shielding purity and coverage
- Trailing shield and back-purge arrangement
- Post-weld shielding time before hot metal is exposed to air
What to Check Next
- Surface color bands versus the acceptance method used on the job
- Trailing shield geometry and gas stability
- Whether the application needs aerospace-specific requirements under AWS D17.1/D17.1M:2024
Related tools:
- Safety & Emissions Calculator
- Laser Safety Planning Guide
- Quality Standards Matrix
General Q&A
Common questions organized by topic area.
Process Basics
What is the difference between keyhole and conduction mode welding?
Keyhole mode occurs at high power densities where a vapor cavity forms, allowing deep penetration with narrow beads. Conduction mode operates at lower power densities, producing wide, shallow welds through surface heat conduction.
How do I determine the right laser power for my application?
Power requirements depend on material type, thickness, joint geometry, desired travel speed, focus condition, and heat sinking. Use the Energy & Heat Calculator to create a starting range, then confirm it with test welds and inspection.
What shielding gas should I use?
Argon is a common starting point for stainless steel, aluminum, and titanium trials, but gas selection depends on material, joint access, oxide sensitivity, and quality target. Titanium and other reactive materials often need trailing or back-side shielding control.
Troubleshooting
Why is my weld full of porosity?
Start by checking surface condition, oxide or moisture, shielding coverage, gas delivery, focus, and keyhole stability. Change one variable at a time and confirm the result with visual inspection or a cross-section where hidden pores matter.
How do I fix spatter and excessive metal ejection?
Spatter often points to unstable keyhole behavior, excessive local intensity, surface contamination, or poor plume control. Check power, speed, focus, gas delivery, and material cleanliness one variable at a time.
What causes weld cracking?
Cracking can come from thermal stress, restraint, solidification behavior, material chemistry, or cooling rate. Check carbon equivalent, restraint, weld sequence, preheat need, and inspection results with the Crack Risk Calculator as a screening tool.
Materials
Can I weld aluminum without preheating?
Some aluminum applications can be welded without preheat, but the decision depends on thickness, alloy, heat sinking, moisture risk, and distortion limits. Surface cleaning and oxide control are usually the first checks.
Why is copper so difficult to weld with lasers?
Copper combines high reflectivity at common infrared wavelengths with high thermal conductivity. Check wavelength, preheat strategy, focus stability, surface condition, and fixture heat sinking before assuming more power is the only answer.
What are the special requirements for welding titanium?
Titanium is sensitive to oxygen and nitrogen pickup at elevated temperature. Check primary shielding, trailing shielding, back purging for full-penetration welds, cleaning, and acceptance criteria before production release.
Safety
What laser safety class are welding lasers?
Many open industrial laser welding sources must be treated as Class 4 hazards unless the integrated system has a different verified classification. Check enclosure, interlocks, eyewear optical density, signage, training, and laser safety responsibility against the applicable standard.
What fume extraction is needed?
Use local exhaust or source capture designed for the material and process. Filter selection and air monitoring depend on the metals, coatings, production duty cycle, and local workplace exposure requirements.
How do I calculate safe viewing distance?
Use NOHD (Nominal Ocular Hazard Distance) calculations together with the applicable laser safety standard. Distance varies with power, wavelength, beam delivery, reflections, and enclosure condition. Our Protection Distance Calculator is a planning aid and should be checked against the relevant safety standard and site controls.
Equipment
Fiber laser vs CO₂ laser - which is better?
Fiber lasers are common for modern metal welding because they integrate well with compact beam delivery and automation. The right source still depends on material absorption, wavelength need, power range, service model, and process target.
What beam quality (M²) do I need?
Lower M2 generally improves focusability, but the requirement depends on spot size, working distance, optics, penetration target, and tolerance to spatter. Treat beam quality as one part of the full optical setup.
How much maintenance does a fiber laser require?
Maintenance depends on source type, optics contamination, cooling system, protective window life, and production environment. Build a routine around protective optics inspection, cooling health, calibration checks, and documented downtime causes.
Can't Find Your Answer?
If your question is not answered here, collect the process facts first:
- Material grade, coating, thickness, joint type, and fixture condition
- Laser power, travel speed, focus position, shielding gas, and nozzle geometry
- Visible defect, cross-section result, resistance or pull-test result when available
- Applicable drawing, inspection method, and standard family
Still Need Help?
Send the collected details through the contact page. A complete process question is much easier to evaluate than a symptom without material, thickness, and parameter context.