A handheld fiber laser welder generates a high-intensity beam inside a fiber laser source, carries it through a flexible fiber-optic cable to a lightweight handheld torch, and focuses it through a lens onto the joint. The beam melts the base metal — and, on most joints, a fed filler wire — to form the weld, guided by hand rather than by a fixed robotic arm.

The beam is near-infrared, at 1080±10nm. That matters for two reasons: metals absorb it efficiently, which is why the process works; and it is completely invisible to the human eye, which is why the safety requirements are stricter than they look. More on that below.

Because the beam is so tightly focused, the heat-affected zone is far narrower than any arc process produces. Less heat spread into the surrounding metal means less warping on thin sheet, less post-weld grinding, and welds that often need little or no cosmetic finishing.

Conduction mode vs keyhole mode

The same machine welds in two distinct regimes, and understanding which one you are in explains most of what you see in the weld pool.

Conduction mode

Lower power density. The surface melts and heat conducts downward and outward, producing a wide, shallow, smooth bead. Good for thin sheet, cosmetic seams and visible joints.

Keyhole mode

Higher power density. The beam vaporises a narrow column of metal, opening a cavity that lets energy penetrate deep into the joint. Produces a narrow, deep weld with a high depth-to-width ratio — this is where laser welding pulls decisively ahead of arc processes on penetration.

Most handheld work sits between the two, and the beam's side-to-side oscillation across the joint — set by scan width — is what lets you widen an otherwise very narrow weld to bridge a gap or cover a joint properly.

Beam oscillation and why it matters

A raw focused laser spot is very small — often well under a millimetre. On a real-world joint with imperfect fit-up, that narrow beam would simply cut a slot rather than bridge the gap. Handheld heads solve this by oscillating the beam across the joint, which effectively widens the weld, improves gap tolerance and evens out the heat. Adjusting scan width and scanning speed is one of the main things an operator tunes on the job.

The LUX Series water-cooled models (LUX-1500 / LUX-2000 / LUX-3000) are not single-purpose welders. The same laser source and torch handle four jobs by changing the head and the settings:

Welding

Butt, lap, fillet and corner joins on mild steel, stainless steel and aluminium, with or without filler wire depending on joint type and gap.

Cutting

Clean, narrow-kerf cuts on sheet metal without setting up a separate plasma or oxy-fuel rig. Practical for thinner gauges; a dedicated cutting machine still wins on thick plate and volume.

Rust removal

The beam vaporises surface oxide, paint and coatings without abrasive blasting, chemicals or the containment those require. Also used for pre-weld surface preparation.

Weld seam cleaning

Strips discolouration, oxide and spatter from a finished weld for a paint-ready or cosmetic finish — particularly useful on stainless, where heat tint is otherwise a manual polishing job.

How readily a metal absorbs a 1080±10nm beam largely determines how easily it welds. Highly reflective metals are harder, and reflection is not just an efficiency problem — light bounced back up the beam path can damage the laser source itself, which is why modern machines include back-reflection protection.

Dissimilar metals

Laser welding handles some dissimilar-metal combinations better than arc processes, because the small, controllable heat input limits the brittle intermetallic layer that forms at the interface. It is not a free pass — some pairings will never make a sound structural joint — but it opens options worth testing on a sample before committing.

Output power and weld thickness scale together across the range. Thin-gauge work in a single-phase workshop sits at the air-cooled end; heavier, continuous production on thicker plate moves up to the water-cooled, three-phase LUX-3000.

Three questions that usually settle it

What is your thickest regular job?

Specify for the work you actually do repeatedly, not the one-off outlier. Quoted maximums assume good conditions; leaving headroom above your normal range gives you consistent results rather than working the machine at its limit.

What power supply does the site have?

The jump from single-phase to three-phase at the LUX-3000 is a real installation consideration and cost, not a footnote. Confirm what is available at the bench before choosing.

How continuously will it run?

Air-cooled units suit intermittent work. Water-cooled units handle sustained duty cycles better — for production runs rather than occasional repairs, that difference matters more than the headline power figure.

Not welding? The same beam removes rust and coatings

If the job is surface preparation rather than joining metal — stripping rust, paint or mill scale before welding, or cleaning a finished weld — the dedicated laser cleaning range handles that without abrasive blasting or chemicals.

Laser welding is not a universal replacement for arc welding — it is a different tool for a different job, and the trade-offs are usually the deciding factor.

When arc welding is still the right answer

• Thick structural sections beyond the machine's rated penetration.
• Field repair work with poor fit-up, awkward access or no ability to control the surrounding area.
• Site work where establishing a controlled laser area is impractical.
• Highly reflective materials outside the machine's comfortable range.
• Low-volume occasional welding where the capital outlay will not pay back.

Most shops that adopt laser welding end up running it alongside their existing arc equipment rather than replacing it outright. That is a reasonable outcome, and worth planning for rather than treating as a failure of the investment.

When you need filler wire

On tight-fitting thin joints, laser welding is often autogenous — the base metal alone forms the weld and no filler is needed. Filler wire earns its place when you need to bridge a gap, build up a fillet, add reinforcement to the bead, or adjust weld metal chemistry (for example, matching filler on aluminium to avoid cracking). Wire feed speed becomes another variable to balance against travel speed and power.

Fit-up tolerance

This is the honest limitation of the process. A focused laser is far less forgiving of poor fit-up than MIG, which can flood a sloppy gap with filler. A wider scan width widens the tolerance considerably, but joints still need to be reasonably clean, aligned and clamped. Shops moving from arc welding usually find that prep and fixturing discipline matters more than it used to — that is a workflow change, not just an equipment change.

Five parameters govern every weld. Understanding what each one physically does — rather than treating them as arbitrary numbers on a screen — makes it far easier to diagnose a bad weld and dial in a good one.

Parameters

Scanning speed

How fast the beam oscillates side to side across the joint — the number of sweeps completed per second, independent of how wide each sweep is.

Scan width

The lateral distance the laser beam sweeps on each oscillation.

Peak power

The maximum output laser power reached during each pulse (or continuously, in CW mode).

Duty cycle

The proportion of time that the laser is on per unit time.

Pulse frequency

The number of laser pulse swings per second.

Scanning speed and scan width together describe the beam's oscillation pattern: scan width is how far it sweeps side to side, scanning speed is how quickly it completes each sweep. Peak power, duty cycle and pulse frequency describe the beam's pulsing over time — power output rises and falls in a repeating on/off pattern, with frequency setting how often it pulses and duty cycle setting what share of each cycle the laser is actually firing.

Reading the parameters against weld quality

The table below is reproduced from Megmeet's own LUX-3000 user manual (Table 3-2, "Welding process reference"). It gives starting wire feed speed, scan width and peak power by workpiece thickness, for the three wire diameters and two material families the manual covers. Treat these as a starting point for trial welds, not a substitute for your machine's own manual — the manufacturer only publishes wire feed speed, scan width and peak power here; there is no published scan-speed or pulse-frequency table to reproduce.

Ø1.0mm wire — carbon steel & stainless steel

Ø1.0mm wire — aluminium alloy

Ø1.2mm wire — carbon steel & stainless steel

Ø1.2mm wire — aluminium alloy

Ø1.6mm wire — carbon steel & stainless steel

Ø1.6mm wire — aluminium alloy

Shielding gas is the variable most often blamed last and responsible first. When welds come out porous, grey or unexpectedly brittle, the gas — its type, its flow rate, or something disturbing it — is a more common culprit than the machine settings people spend their time adjusting.

What the gas is actually doing

Excluding the atmosphere

Molten metal readily absorbs oxygen and nitrogen from the air. Oxygen causes oxidation, dross and porosity; nitrogen causes brittle nitrides in some metals. The gas displaces air from the weld pool and the hot metal around it.

Clearing the vapour plume

Vaporised metal rises off the weld as a plume that can scatter and absorb part of the beam before it reaches the joint. Gas flow pushes it aside, keeping energy delivery consistent. This mattered enormously on older CO₂ lasers; at fiber wavelengths it is less severe but still worth getting right.

Protecting the optics

Gas flow through the nozzle helps push spatter and vapour away from the protective window — the cheapest consumable on the machine and the one guarding the expensive optics behind it.

Shielding the cooling weld

Metal keeps reacting with the atmosphere well after the beam has moved on. Post-flow coverage of the still-hot weld matters on stainless and is critical on titanium.

Choosing a gas

Gas by material

Gas selection by material — detailed reference

Flow rate: more is not better

Handheld laser welding typically runs somewhere in the region of 10–20 litres per minute, but treat that as orientation only — the correct figure depends on your nozzle, head design, joint geometry and the conditions at the bench. Your machine's manual gives the number that matters.

The counter-intuitive part is the upper limit. Turning the flow up past the right point creates turbulence at the nozzle, and turbulent flow draws surrounding air into the shield rather than excluding it. The result looks exactly like too little gas — porosity and oxidation — which sends people in precisely the wrong direction when they try to fix it by opening the valve further.

• Use welding-grade gas. Industrial or balloon-grade gas carries moisture and contaminants that show up directly as porosity.
• Check hoses and fittings for leaks — a slow leak starves the weld while the flow meter still reads normally.
• Purge the line before critical work, particularly if the machine has stood unused or the cylinder was just changed.
• Set post-flow long enough to cover the weld until it is no longer reactive; short post-flow is a common cause of tinted, oxidised weld tails.
• Keep the nozzle clean. Spatter build-up distorts the gas pattern long before it looks bad enough to notice.

Draughts will quietly ruin your welds

A shielding gas envelope is fragile. An open roller door, a pedestal fan, someone walking past, or fume extraction positioned to pull across the weld rather than up from it will strip the shield away faster than the flow can replace it. This is one of the most common causes of porosity that appears to have no explanation, because nothing about the machine has changed.

Extraction placement in particular is worth thinking about carefully: you need it running for fume safety, and it is entirely possible to position it so that it does its job and sabotages your gas coverage at the same time. Pull the fume upward and away rather than laterally across the joint.

Reading the weld for gas problems

Why 1080±10nm is more dangerous than it looks

The beam is near-infrared and invisible. There is no visible flash, no arc glare, and critically no blink reflex — the involuntary response that gives some protection against bright visible light simply does not trigger. Worse, wavelengths in the 400–1400nm range pass through the transparent structures at the front of the eye and are focused by the lens onto the retina, concentrating the energy substantially. Damage can occur faster than any human reaction, and without pain at the moment it happens.

This is the single most important thing to understand about the process: an arc welder's instincts about "looking away" and "shielding your eyes from the bright bit" do not transfer, because there is no bright bit.

Eye protection

Optical density (OD) — what the rating means

Optical density is a logarithmic measure of how much laser energy the eyewear blocks. Each increase of 1 OD reduces laser energy by a factor of 10.

Because handheld laser welders operate at very high power, eyewear typically requires OD 8 or higher at the operating wavelength to reduce exposure below MPE limits.

• A standard welding helmet, auto-darkening lens or ordinary safety glasses do not protect against 1080±10nm laser radiation. Shade rating is not the same as laser optical density.
• You need laser safety eyewear or a laser-rated visor specified for the machine's wavelength (1080±10nm) and rated to an optical density adequate for its power — check the specification supplied with the machine rather than assuming any laser eyewear will do.
• The wavelength and OD rating are marked on compliant eyewear. If you cannot read that marking on a pair, do not use it for this machine.
• Worn any time the machine is capable of firing — not only during active welding.
• Inspect eyewear regularly. Scratches, pitting or damaged filters compromise protection.
• Many operators need protection against the visible plume as well as the beam; some products combine both, but confirm rather than assume.

Reflections are the hazard people underestimate

Welding is done on metal, and metal reflects. A specular (mirror-like) reflection off a polished stainless surface can carry a substantial fraction of the beam energy in an unpredictable direction — potentially remaining hazardous at a considerable distance from the work. This is why the controlled-area requirement exists and why bystanders matter.

• Establish a defined laser-controlled area, with the work enclosed or screened by laser-rated curtains or barriers — not ordinary welding screens, which are designed for arc glare and spatter, not infrared laser radiation.
• Post warning signage at entry points, and restrict access while the machine is in use.
• Everyone inside the controlled area wears appropriate eyewear — operators, helpers, supervisors and visitors alike.
• Remove unnecessary reflective objects from the beam's potential path, and be conscious of polished tooling, benches and jigs.
• Never aim or fire the torch outside the intended work area, and never point it at anyone, powered or not.

Fume and extraction

The process vaporises metal and anything on it, producing a fine fume plume with very small particle sizes. Some of what it produces is seriously hazardous:

Stainless steel

Produces hexavalent chromium, a recognised human carcinogen. Local exhaust ventilation at the weld is required, not optional.

Galvanised / zinc-coated steel

Zinc oxide fume causes metal fume fever — flu-like symptoms following exposure. Strip the coating first where possible, and extract regardless.

Painted, plated or coated metal

Unknown coatings produce unknown decomposition products. Identify and remove the coating rather than burning through it and hoping.

Cleaning and rust-removal modes

These modes exist specifically to vaporise surface material, so they generate significant fume by design. Treat extraction as a core requirement of the process, not an optional extra.

Fire, electrical and other hazards

• A Class 4 beam readily ignites combustible material. Clear the area of solvents, rags, cardboard, sawdust and packaging, and keep appropriate fire extinguishing equipment at hand.
• Skin exposure causes burns. Cover exposed skin; the same beam that welds steel will damage tissue instantly.
• High-voltage electrical hazards exist inside the enclosure. Only qualified personnel should open the machine, and only after full isolation.
• Water-cooled machines combine electricity and coolant. Check for leaks before and during use, use the specified coolant, and follow the maintenance schedule.
• Compressed gas cylinders must be secured upright, stored correctly and checked for leaks. Argon and nitrogen are asphyxiants that displace oxygen without warning — never run a gas line into a pit, tank or other confined space, and ventilate enclosed work areas.

Interlocks and controls

• Never bypass, tape down, defeat or modify the torch safety switch, footswitch interlock, enclosure interlock or emergency stop. These are the last line of defence against an unintended firing.
• The safety switch on a handheld torch exists specifically so the beam cannot fire unless the head is in contact with the workpiece. Defeating it removes the protection that makes handheld operation viable at all.
• Test the emergency stop as part of routine checks, and know where it is before you need it.
• Use the key control where fitted, and restrict keys to trained operators. An untrained person should not be able to fire the machine.

Training, responsibility and regulation

In South Africa, employers carry general duties under the Occupational Health and Safety Act (85 of 1993) to provide a safe working environment, which includes appropriate training, personal protective equipment and risk assessment for equipment like this. Laser safety classification internationally follows the IEC 60825 standard series, and best-practice frameworks such as ANSI Z136.1 set out the concept of a designated Laser Safety Officer responsible for controls, training and the controlled area.

Because the specific obligations depend on your site, your workforce and how the machine is used, treat the above as orientation rather than a compliance checklist — confirm your own duties with a qualified occupational health and safety practitioner, and keep records of training and risk assessments.

• Train every operator before they use the machine, on both welding technique and laser-specific hazards.
• Designate someone responsible for laser safety, controlled-area rules and PPE availability.
• Keep the manufacturer's manual accessible at the machine — it takes precedence over general guidance, including this page.
• Brief anyone entering the area, including visitors, contractors and management.
• Document your risk assessment and review it when the work or the material changes.

A short pre-use check that catches most of what goes wrong:

• Laser safety eyewear on, correct wavelength and rating, undamaged — everyone in the area
• Controlled area screened, signed and access restricted
• Combustibles cleared from the work area; fire extinguisher within reach
• Fume extraction running and positioned at the weld
• Material identified; coatings stripped or accounted for
• Joint clean, aligned and clamped
• Shielding gas connected, cylinder secured, flow correct
• Protective lens inspected — clean and unpitted
• Coolant level and flow checked (water-cooled machines)
• Interlocks and emergency stop confirmed working
• Machine settings matched to material and thickness

Running costs on a fiber laser are low compared with arc welding — there are no electrodes or contact tips burning away — but the items that do wear are the ones standing between the beam and your focusing optics. Neglecting them is how a cheap part becomes an expensive repair.

Protective window / cover lens

The most important consumable on the machine. It shields the focusing lens from spatter and vapour. Inspect it regularly: a contaminated or pitted window absorbs energy, overheats, degrades weld quality and can fail — allowing damage through to far more expensive optics behind it. Replace it early rather than late.

Nozzles

Wear and spatter build-up distort gas flow and beam clearance. Keep spares in the sizes you use routinely so a worn nozzle never becomes a reason to keep working with a bad one.

Ceramic bodies and seals

Wear items on the head assembly. Damaged seals compromise gas coverage and allow contamination into the optical path.

Collimating and focusing lenses

Longer-life optics, but they do eventually need attention. Clean strictly per the manufacturer's method — improper cleaning damages coatings.

Coolant (water-cooled machines)

Use the specified coolant and change it on schedule. Contaminated or incorrect coolant causes scaling and cooling failure, which is a laser-source problem, not a plumbing one.

Filler wire and shielding gas

Ordinary stock items, but keep wire clean and dry — surface contamination shows up directly in weld quality.

Quick definitions for terms used throughout this guide. Each links back to the section it's discussed in.

Conduction mode

See: What is laser welding? →

Lower power density welding regime where the surface melts and heat conducts downward and outward, producing a wide, shallow, smooth bead.

Keyhole mode

See: What is laser welding? →

Higher power density regime where the beam vaporises a narrow column of metal, producing a narrow, deep weld with a high depth-to-width ratio.

Autogenous welding

See: Filler wire and fit-up →

Welding where the base metal alone forms the weld, with no filler wire added.

Scanning speed

See: Machine settings explained →

How fast the beam oscillates side to side across the joint — sweeps completed per second, independent of scan width.

Scan width

See: Machine settings explained →

The lateral distance the laser beam sweeps on each oscillation.

Peak power

See: Machine settings explained →

The maximum output laser power reached during each pulse, or continuously in CW mode.

Duty cycle

See: Machine settings explained →

The proportion of time the laser is on per unit time.

Pulse frequency

See: Machine settings explained →

The number of laser pulse swings per second.

Back-purging

See: Shielding gas →

Purging the underside (root) of a full-penetration joint with shielding gas to protect it from the atmosphere — worth considering on austenitic stainless.

Back-reflection

See: Materials: what welds well, what needs care →

Laser light reflected off a highly reflective workpiece back up the beam path toward the laser source, which can damage the source — the reason modern machines include back-reflection protection.

Optical density (OD)

See: Safety: what a Class 4 laser demands →

A logarithmic measure of how much laser energy protective eyewear blocks. Each increase of 1 OD reduces laser energy by a factor of 10.

Protective window / cover lens

See: Consumables and upkeep →

The consumable window that shields the focusing lens from spatter and vapour — the most important consumable on the machine.