Flexible Laser Treatment: How a Flexible Laser System Actually Works

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  What makes flexible laser treatment flexible
• 2
  Cutting, welding and drilling: three different heat budgets
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  Where flexible laser treatment runs into trouble
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  What a flexible laser system can and cannot hold
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  Batch size decides whether flexibility is worth the setup
• 6
  Flexible laser system compared with fixed tooling

A laser head is a tool with no cutting edge and no contact force. That single fact explains most of its flexibility. The beam can be focused to a spot under 0.1 mm or defocused to a 6 mm line, moved at 100 mm/s or 10,000 mm/s, and switched between continuous and pulsed output. The same head can cut a 1 mm stainless shim in the morning and weld a 3 mm aluminium bracket after lunch. No fixture change is needed for the tool itself.

The second source of flexibility is programmability. Cutting paths, weld seams and drill positions live in a text file, not in a hardened die. Change the file and the machine changes job. A 0.5 mm wall does not deflect because nothing touches it. The part still needs a way to sit in the cell, and that fixture is often the slowest thing to change.

Beam delivery matters too. A gantry system moves the workpiece under a fixed optic; a robot arm carries the optic to the part. Gantry machines hold tighter position, often ±0.05 mm over 2 m of travel. Robot arms reach into a weldment that will not fit on a table, but they lose accuracy at the end of a 2 m arm.

None of this removes physics. The beam still couples heat into the part, and heat moves. Flexibility in path does not mean flexibility in distortion.

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  No contact forceThin walls and finished surfaces survive without clamping marks.
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  Path is softwareA program edit replaces a new die or a new electrode.
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  Delivery sets accuracyGantry holds position; robot arm wins on reach.

Cutting wants a small heat-affected zone and a clean kerf. Fiber lasers at 1–6 kW cut 1 mm stainless at roughly 8–15 m/min with nitrogen assist, and 3 mm mild steel at 2–4 m/min with oxygen. The kerf on 1 mm stainless typically runs 0.1–0.3 mm wide. Taper grows with thickness, so a 6 mm cut may show 0.05 mm of taper per side.

Welding wants the opposite: enough energy to fuse, not enough to keyhole through. Conduction welding at 1–3 kW suits 0.5–2 mm sheet and produces a smooth bead with low spatter. Keyhole welding at 3–6 kW penetrates 3–8 mm in one pass on steel, but it is far less forgiving of fit-up gaps. A gap over 10% of the sheet thickness usually needs filler wire.

Drilling sits between the two. Percussion drilling punches a 0.1–1 mm hole in microseconds with a single pulse, which is why it works on fuel injector nozzles and cooling holes. Trepanning cuts a circular path with the beam and holds a rounder hole, at the cost of cycle time.

The engineering meaning is simple. Each of these processes has its own power, speed and gas window. A flexible laser system is flexible because it can switch windows, not because it ignores them.

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  Cutting1–6 kW, nitrogen or oxygen assist, 0.1–0.3 mm kerf on thin sheet.
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  Welding1–3 kW conduction for thin sheet; 3–6 kW keyhole for 3–8 mm steel.
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  DrillingPercussion for 0.1–1 mm holes; trepanning when roundness matters.

Aluminium reflects near-infrared light until it melts, so a fiber laser needs higher peak power to start the cut. Once the keyhole opens, absorption climbs and the process runs normally. The practical problem is dross on the underside of thick aluminium, which usually means more assist gas pressure and a slower feed.

Copper and brass are worse. Reflectivity at 1 μm can exceed 90% at room temperature, and back-reflection can damage the delivery fiber. Blue and green lasers at 450–515 nm absorb far better in copper, which is why they appear in busbar and battery work. If your part is copper, ask which wavelength the shop runs before you assume a fiber source will do it.

Titanium and Inconel cut and weld well but oxidize fast. Titanium welds need argon shielding on both sides, and the bead must stay silver; a straw or blue color means contamination. Inconel holds heat and tends to warp on thin sections, so fixture cooling helps.

Plastics and composites behave differently again. CO2 lasers at 10.6 μm cut acrylic and wood cleanly, while fiber lasers at 1 μm often pass through transparent plastics without coupling. Carbon fiber cuts but leaves a charred edge that needs trimming.

The rule: match the wavelength to the absorption, then match the gas and the fixture to the material.

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  AluminiumUse higher peak power and more assist gas to control dross.
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  Copper and brassNear-infrared reflects; blue or green sources absorb better.
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  TitaniumShield both sides; a silver bead means a clean weld.

Laser cutting is not a precision finishing process. On 1 mm stainless, a well-tuned fiber laser holds about ±0.1 mm on the profile and ±0.05 mm on hole position. On 6 mm steel, expect ±0.2 mm. These numbers come from kerf width, taper and thermal drift over a long nest, not from the motion system alone.

If the drawing calls for ±0.005 mm, or a bore that must hold an H7 fit, laser cutting is the wrong first operation. The usual route is laser cut the blank, then finish the critical features on a CNC. GreatLight runs 127 high-precision CNC machines, including 16 simultaneous 5-axis machining centers and a Ø400 mm rotary table, so a laser blank can move straight into milling and turning without a second supplier.

Edge quality also matters. Laser-cut edges are square and clean but carry a thin oxide layer and a small HAZ, typically 0.05–0.2 mm deep. If that edge will be welded, the oxide must come off first, usually by brushing or pickling. If it will be anodized, the HAZ can show a color difference against the parent metal.

Surface finish is the other gap. Laser cutting leaves Ra 3–6 μm on the cut face. Where the drawing asks for Ra 0.2–0.8 μm, that face needs machining, not more laser passes.

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  Cut profileAbout ±0.1 mm on 1 mm stainless; ±0.2 mm on 6 mm steel.
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  Critical fitsLaser the blank, then finish bores on a CNC at ±0.005 mm.
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  Cut faceRa 3–6 μm as cut; machining needed below that.

A flexible laser system earns its keep in the middle of the volume curve. For one to a few hundred parts, the setup is a program load and a fixture location, not a die. Changeover between two different brackets can take minutes. That is where flexible laser treatment beats a press or a dedicated hard-tooled line.

At very high volume, the economics flip. A progressive die costs more up front but runs a stamped part in under a second. A laser takes several seconds per part plus gas and power. Above tens of thousands of parts per year, the die usually wins on unit cost, provided the geometry stays stable for the life of the program.

The awkward zone is the redesign-heavy program. A die freezes geometry. A laser does not. If the bracket will change every quarter, paying for a die three times is worse than paying a higher unit cost at the laser.

Small batches also matter for prototypes. The first article off a laser is a real part, not a simulation. Engineers can hold it, weld it and break it, then change the CAD the same day.

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  1 to a few hundred partsLaser wins; changeover is a program edit.
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  Tens of thousands and upA dedicated die usually wins on unit cost.
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  Design still movingLaser absorbs revisions without new tooling.