WELDING EQUIPMENT

Laser welding cells: sources, heads, tracking and safety

What actually separates one laser welder from another, from fit-up limits and source options to seam tracking, enclosures and laser classification.

By WeldOrigin Editorial · Published · Updated

Fit-up decides more than power

TWI describes two laser welding modes. Below roughly 10⁵ W/cm² the beam is absorbed at the surface and the weld is wide and shallow (conduction mode). Above roughly 10⁶ to 10⁷ W/cm² the metal vaporises into a keyhole that couples the beam deep into the joint and leaves a narrow, deep weld. TWI calls keyhole the more common mode, and its narrow weld creates the buyer's main problem: the beam must land on a closed joint.

TWI's rule of thumb for butt joints is a gap below about 10% of material thickness. Clamping closes gaps on thin sheet; weaving or spinning the beam raises tolerance to roughly 20 to 30% of thickness at lower speed; filler wire can take steels up to 6 mm to about 100% of thickness, again more slowly; hybrid laser-arc welding adds further margin. Describe parts, edge preparation and realistic gaps before anyone quotes a laser welding system. For very small, thin components, microplasma, as offered by Eweld, may deserve a trial alongside the laser.

Handheld unit, workstation, robot cell or dedicated line

The Penta Laser pages on this site show the formats on offer. The SWAN air-cooled handheld series lists 500, 800 and 1200 W variants, and the water-cooled SWAN HW family lists 1000 to 3000 W with single- or dual-axis oscillating heads. Handheld units suit varied, accessible joints but leave positioning and much of the fit-up risk to the operator.

The IPW 0503S is an enclosed bench station for small parts with a 500 × 300 × 200 mm envelope. The RW 1510P robot welding platform adds robot motion, a positioner and an enclosure around a stated 1500 × 1000 × 400 mm working area. Dedicated machines go further: the WEX 4020 welds heat-exchanger pillow plates over a 4000 × 2000 mm field, and the GAN 2412 gantry targets square electrolysers.

Line builders such as Mingtai supply stator-core and battery-related stations where loading, inspection and integration define the project. Pick the format from part size, volume and variation, then compare models.

Reading source, power and head options

Power figures on these datasheets are often a menu rather than a rating. Penta's IPW 0503S and RW 1510P list 300 to 6000 W and the WEX 4020 1000 to 8000 W, each spread across four laser source codes that the pages do not explain. The source and power on your quotation, not the model name, define the machine, so ask for the source maker, type, rated power and delivery fibre.

Across its range Penta offers collimating-and-focusing heads, swing or oscillating heads, 2D and 3D galvo scanners and composite heads. An oscillating head is one practical route to the beam weaving TWI mentions for wider gaps. Keep the head that produced the accepted samples on the order.

Check utilities as you would on any power source nameplate: the air-cooled SWAN page gives a 220 V supply without stating phase, while the platforms list 380 VAC at 50 Hz and compressed air at 0.5 to 0.7 MPa. For water-cooled units, confirm who supplies the cooling. To line up offers that differ in source, head and cooling, use comparing welding equipment quotations.

Seam tracking, vision and calibration

Because the weld is narrow, TWI says the head must stay aligned within a few tenths of a millimetre or less, and that vision sensors, using low-power laser light and a camera, are used for most laser tracking. Systems track first and then weld, or track while welding. TWI notes limits around 10 m/min, on sharp small-radius paths and on tightly butted edges that return too little signal.

Penta describes the GAN 2412 seam tracking as exclusive but publishes no method. Ask which sensor is fitted and what accuracy it achieves on your seam. The IPW and RW platforms list automatic visual positioning calibration as an option; locating a part before welding differs from following a seam that shifts during welding.

Plants running arc-welding robots, for example from Kaierda, should not assume their joint-finding methods carry over. TWI rates conventional arc sensors, such as voltage and tactile types, generally unsuitable for laser work on accuracy and update rate.

Enclosures, classification and the user's duties

IEC 60825-1 (edition 3.0, 2014) classifies laser products by their optical radiation hazard and requires the manufacturer to supply labels and information so users can take precautions. It covers lasers built into larger systems but excludes components sold to other manufacturers for incorporation. So the builder of the finished machine, not the source maker, should state the class of the complete machine as delivered, with its labels and manual.

An enclosed bench such as the IPW still needs its shield, viewing window and door interlocks defined in the offer, as does a robot cell enclosure. Handheld units have no enclosure, so the work area itself must be controlled. Biaoke's profile on this site makes the related point: ask who assesses the laser hazards of the installation and who provides the controls at your site.

HSE explains that the Control of Artificial Optical Radiation at Work Regulations protect workers in Great Britain and expect employers with hazardous sources to reduce risks as low as reasonably practicable; other countries apply their own rules. Have a competent person review the installation, and see verifying welding equipment certificates before relying on a declaration.

Trials, fixtures and handover

Clamps that close the gap are part of the process window TWI describes, so fixture design belongs in the quotation; welding fixtures and tooling covers ownership and spare parts. Penta's GAN 2412 page also raises titanium and nickel shielding for electrolyser welds.

Run the trial on your own parts, including worst-case gaps and surface condition, and record source, power, head, oscillation, gas and tracking settings with each accepted sample. The sample trials and acceptance guide explains how to fix criteria in advance. For stator or battery work, Mingtai's profile shows why loading, inspection and variants belong in the trial too. Where the laser is one station in a line, handle it as a welding automation project with defined interfaces, commissioning and on-site acceptance.

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