CNC Laser Cutti: Where It Fits in 2025

• 1
  Key takeaways
• 2
  What cnc laser cutti actually does to sheet metal
• 3
  Which materials and thicknesses stay economical
• 4
  What tolerance a laser can and cannot hold
• 5
  When to cut, when to machine, and how to combine them
• 6
  Design rules that keep laser parts cheap
• 7
  Laser cutting versus CNC machining by part type

A laser cutter moves a focused beam across flat stock. The beam melts or vaporizes metal along a programmed path, and an assist gas blows the molten material out of the kerf. That is the whole process. There is no tool touching the part, so there is no tool wear and no clamping force to distort thin sheet.

The practical result is a 2D profile. You get outlines, holes, slots and tabs to whatever shape the nesting software allows. You do not get pockets, counterbores, threads or 3D contours. Those features come from a mill, a lathe or a secondary operation after cutting.

Fiber sources dominate new installations because they cut mild steel, stainless and aluminum efficiently and run on far less power than the older CO2 cabinets. CO2 still has a place, mainly thick acrylic, wood and some coated non-metals where the 10.6 μm wavelength absorbs better.

For most job shops the decision is not which laser to buy. It is whether the part should be cut at all, or machined from solid. That call comes down to thickness, tolerance and feature geometry, which we cover below.

Mild steel and stainless are the bread and butter. A 6 kW fiber source cuts 1 mm mild steel at high speed and still handles 20 mm plate, though edge quality drops as thickness climbs. Stainless cuts cleanly up to roughly 12 mm with nitrogen assist, which gives an oxide-free edge.

Aluminum is trickier. It reflects the beam and conducts heat away fast, so cut quality on thick plate is worse than on steel. Under 6 mm it is fine. Above 10 mm expect rougher edges and slower speeds, and consider machining instead.

Copper and brass behave like aluminum but more so. A fiber laser will cut thin sheet, but the reflection risk means many shops decline thick copper on a laser and route it to a mill. Titanium cuts well in thin gauges but needs argon assist and a clean, dedicated setup.

Plastics and composites are a separate world. Acrylic cuts beautifully on CO2 with a polished edge. Carbon fiber and glass-filled plastics cut, but the edge is charred and the dust needs extraction. PEEK and similar high-temperature plastics are usually machined, not lasered.

A laser holds position well, but the cut itself has a kerf, a slight taper and a heat-affected zone. On 1–3 mm sheet you can typically hold ±0.1 mm on profile dimensions with a good machine and clean nesting. On 10 mm plate, expect ±0.2 mm or worse, plus taper that varies with speed and gas pressure.

That is fine for brackets, covers and weldments. It is not fine for a bearing bore, a press-fit pin hole or a sealing face. When a drawing calls for ±0.005 mm, laser cutting is the blank, not the finished part.

The heat-affected zone matters on hardened or pre-treated stock. Cutting a hardened steel plate can leave a brittle edge that cracks under load. Annealed or normalized stock cuts predictably. If the part is heat treated after cutting, that is usually the cleaner route.

Hole quality degrades fastest. A hole smaller than the material thickness tends to come out tapered and slightly undersized. The common rule is to keep hole diameter at least equal to sheet thickness, and to add a machining pass if the hole is functional.

Laser first, machine second is the standard hybrid route. The laser produces a flat blank with the outline, lightening holes and slots already in place. A mill then finishes datums, bores, threads and faces. This cuts roughing time dramatically on parts that start as plate.

For parts under about 3 mm thick with loose tolerances, laser alone is usually the cheapest path. Send the DXF, get the parts. No tooling, no minimum order quantity. For parts over 12 mm with tight tolerances, starting from a laser blank and machining the rest often beats cutting everything from solid.

The middle ground needs a judgment call. A 6 mm aluminum bracket with two precision bores is a hybrid part. A 6 mm aluminum bracket with only slots and outlines is laser-only. The question is always which features actually need the tighter number.

At GreatLight we run both sides of that line. The cutting cell produces blanks and flat profiles, and 127 high-precision CNC machines handle the secondary work, including 16 simultaneous 5-axis machining centers for contoured parts. One supplier, one inspection report.

Keep the minimum hole diameter at or above the sheet thickness, and never smaller than 1 mm on thin gauge. Small holes in thick plate are where scrap rates jump. If the hole is functional, plan a reaming or boring pass instead of fighting the kerf.

Corner radii matter more than most drawings show. A sharp internal corner is impossible to cut cleanly because the beam has a finite width. Give every internal corner a radius of at least half the sheet thickness. This also helps the machine run at a steady speed, which reduces dross.

Spacing between parts and to the sheet edge should be at least the sheet thickness, often more. Too close and the heat from one cut distorts the neighbor. Nesting software will handle this, but only if the geometry allows it in the first place.

Finally, mark the drawing with which dimensions are critical and which are reference. A laser shop will hold the critical ones and let the rest float. Marking everything tight forces a slower, more expensive process for no functional gain.