Introduction to the Three Dimensional Laser Cutting Machine

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  How a three dimensional laser cutting machine follows a curved surface
• 2
  What three dimensional laser cutting actually cuts well
• 3
  Tolerance and edge quality you can expect
• 4
  Design rules before you send a 3D laser part
• 5
  Where 3D laser cutting sits in a real program
• 6
  How we handle 3D laser and hybrid work at GreatLight
• 7
  Three dimensional laser cutting compared with other processes

A flat-bed laser moves in two axes, X and Y, and the sheet lies still under it. A three dimensional laser cutting machine adds a rotary or tilting head plus a controlled Z axis, so the nozzle can stay perpendicular to a surface that is not flat. That single change is what separates the two machine classes.

The head is not simply a mirror on a gantry. Most systems carry a small two-axis galvanometer scanner that steers the beam, and the machine axes move the scanner to the right place above the part. The scanner handles the fast local motion, the gantry and rotary axes handle the large travel. Splitting the work this way keeps the beam on the cut path even when the surface tilts 30° or more.

Focus position matters more than most people expect. The usable depth of focus on a fiber laser head is often only 0.5–1.5 mm for thin sheet, so a surface that drifts 2 mm in height will lose the cut. That is why 3D systems pair the head with capacitive height sensing or a camera, and why the Z axis is closed-loop rather than fixed.

The cutting gas does a second job on curved work. On a flat sheet the assist gas only clears the kerf. On a tilted surface it also has to push molten metal out of a groove that gravity is pulling back in. Downward-facing cuts on thick steel are the hardest case, and they are where dross and re-cast layer appear first.

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  Scanner plus axesFast local steering, slow large motion.
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  Depth of focusOften 0.5–1.5 mm on thin sheet.
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  Height sensingKeeps the nozzle at a fixed standoff.

The process is strongest on sheet and tube that has been formed, not on solid bar. Laser-cut work typically starts as 0.5–6 mm sheet that was stamped, bent or hydroformed, then trimmed on a 3D cell. The cut edge on mild steel and stainless usually lands in the Ra 0.8–1.6 μm range, which is fine for a trim or a weld prep but not for a sealing face.

Thickness sets the ceiling. Fiber lasers cut 1 mm stainless at several meters per minute, but the same beam on 8 mm steel is slow and the taper grows. On curved surfaces the effective thickness along the beam is larger than the wall thickness, so a 3 mm wall at 45° behaves like roughly 4.2 mm of material. Plan the process around the angled thickness, not the flat number.

Aluminium is workable but reflective, and the cut edge oxidizes within hours unless the parts are cleaned and packed. Titanium needs an inert shield or the cut edge picks up oxygen and turns brittle. Coated stock, such as galvanized or painted sheet, cuts but releases zinc or paint fumes that have to be extracted at the head.

Plastics behave differently. CO2 sources in the 100 W to 600 W class are common for PMMA and polycarbonate, and they leave a polished edge on acrylic. They do not cut metal. Do not assume one machine covers both jobs; the source and the optics are different.

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  Good fitFormed sheet 0.5–6 mm, tubes, brackets, trim.
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  Poor fitSolid blocks, sealing faces, thick plate over 10 mm.
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  Edge cautionAluminium oxidizes, titanium needs shielding.

Laser trimming is not a precision finishing operation. On a formed panel, the position of a cut relative to a datum hole typically holds around ±0.1 mm to ±0.2 mm, because the fixture, the springback of the formed part, and the thermal drift of the head all stack up. That is enough for brackets, covers and weld preps. It is not enough for a bearing bore.

Where a laser-trimmed edge later needs to locate something, the usual route is to cut undersize and finish on a CNC mill. We hold ±0.005 mm on milled features, so a hybrid plan works well: laser for the outline, milling for the interface. This keeps the laser doing what it is fast at and keeps the tolerance where it matters.

Kerf width on thin sheet is small, often 0.1–0.3 mm, which helps when nesting tight parts. Taper is the trade-off. On a vertical cut the kerf is nearly parallel; on a 45° cut the top and bottom of the kerf differ more, and the difference grows with thickness. If the edge is a visible surface, spec the cosmetic side and let the other side carry the taper.

Heat input is localized but not zero. A tight contour with many small features can build enough heat to distort a thin panel, so sequencing and dwell points matter as much as power. On 1 mm stainless we often run at reduced power with a higher feed rather than full power at low speed.

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  Laser position±0.1–0.2 mm on formed parts.
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  Milled feature±0.005 mm where a bore or face is critical.
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  Kerf0.1–0.3 mm on thin sheet.

Keep the cut path reachable. The head has a physical size, and a deep draw with a narrow opening can block the nozzle before the beam ever reaches the corner. A rule that works in practice: leave an opening at least 30 mm wide for the head to enter, and avoid features deeper than about 40 mm unless the machine has a long, slim nozzle.

Place the cut on a surface the fixture can support. A formed panel that is only clamped at two corners will vibrate, and vibration shows up as a ragged edge and an inconsistent kerf. Add support under the cut line, or design a tab so the part stays stiff until the last pass.

Give the edge a purpose. If the cut edge is cosmetic, say so and we will orient the taper away from the viewer. If it is a weld prep, a small land of 0.5–1 mm helps the weld root. If it is a mating face, expect to mill it. Sending a drawing that marks which edges are cosmetic and which are functional saves a round of questions.

Tolerance callouts should match the process. A blanket ±0.05 mm on every dimension of a laser-trimmed panel will drive cost up or force a re-route to milling. Mark the two or three dimensions that actually locate the part, and leave the rest as general tolerance.

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  Head accessOpening at least 30 mm wide.
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  SupportClamp near the cut, not two corners only.
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  Edge intentMark cosmetic versus functional edges.

The strongest use is a bridge between forming and finishing. A part is stamped or bent to near shape, then laser-trimmed to the final outline after springback. That avoids a trim die, which is expensive and slow to change. For low and mid volume runs, laser trimming is usually the cheaper route to a correct outline.

It also suits tube and extrusion work. Cutting a notch or an angled end on a bent tube is awkward on a mill because the tube is long and floppy. A 3D laser cell handles it with a rotary chuck and a steady rest, and the same setup can cut several features in one pass.

The limit is volume. Once a part is stable and the annual quantity is high, a trim die or a dedicated punch pays back. Laser trimming stays useful for variants, service parts and engineering changes, but it is not the cheapest way to make a million identical brackets.

For prototypes, the sequence is often the reverse. We machine the geometry on a 5-axis center first to prove fit, then move to formed and laser-trimmed parts for pilot builds. That order keeps the early iterations fast and moves cost down only after the design is frozen.

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  Best volume bandLow to mid volume, plus variants and service parts.
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  Tube workNotches and angled ends in one setup.
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  Prototype orderMachine first, then form and laser trim.

GreatLight runs 127 high-precision CNC machines across three wholly-owned plants covering 7,600 m², with 16 simultaneous 5-axis machining centers, 16 mill-turn centers and a Ø400 mm rotary table. That mix matters here: a laser-trimmed part often needs a milled interface, and both operations can sit in one production plan instead of two suppliers.

We work in aluminium 6061, 2024, 5052, 7075, stainless 304, 316L and 17-4PH, steel 1018 and 4140, titanium TC4, copper C110 and C36000 brass, plus ABS, PC, POM, PEEK and PMMA. Finishing runs in house: anodizing, electroless nickel, zinc and black oxide, bead blasting, brushing and laser marking down to 1.5 mm character height.

Inspection is 100% before shipment, with raw material check, in-process monitoring and final inspection, and reports on request. Tolerances hold at ±0.005 mm on machined features and finishes from Ra 0.2–0.8 μm where a surface is critical. The plants hold ISO 9001:2015, IATF 16949:2016, ISO 13485:2016 and ISO 27001:2022.

We quote and return a free DFM analysis within 12 hours, and production can start within 24 hours. There is no minimum order quantity, so a single prototype and a 10,000-part run go through the same process. Uploads are confidential and an NDA is available on request.

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  One planLaser trim and milled interfaces under one roof.
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  MaterialsAluminium, stainless, steel, titanium, copper, plastics.
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  Lead timeQuote in 12 hours, parts ship in 3–5 days.