Machining
Laser or router: choosing the process before choosing the supplier
The same outline can be cut two ways, and the difference shows up on the edge, in the tolerance, and on the invoice.
Machining
The same outline can be cut two ways, and the difference shows up on the edge, in the tolerance, and on the invoice.
Acrylic is one of the few materials where both a laser and a router cut it well, so the choice is not about capability but about what the part needs. The two processes differ on the edge they leave, the accuracy they hold, the holes they make and the volume at which each becomes economic.
| Laser | CNC router | |
|---|---|---|
| Edge finish | Glossy but slightly tapered, with a faint frosted heat-affected band | Matte, square, ready to diamond polish |
| Kerf | 0.2–0.3 mm, slightly tapered through the thickness | Cutter diameter, typically 3–6 mm, with a vertical edge |
| Practical thickness | Up to 12 mm well; 25 mm maximum but quality falls | Any thickness, limited only by cutter length |
| Tolerance | ±0.1 mm on thin sheet, widening with thickness | ±0.1 mm, and better within one setup |
| Hole quality | Fast, but tapered; small holes reliable down to 1 mm | Round and parallel; needs plunge or helical entry |
| Internal corners | Radius is half the kerf, so effectively sharp | Radius equals the cutter radius; a 3 mm cutter cannot make a sharp corner |
| Heat input | Local heating, can leave stress and a smell | Cold cutting, no heat-affected zone |
| Nesting efficiency | Very high, small gaps between parts | Lower, needs clamping and cutter clearance |
| Best for | Thin sheet, intricate outlines, fast prototypes, engraving | Thick sheet, polished edges, tight holes, 3D features |
This is the detail that most often forces a process choice, and it is usually discovered late. A router leaves a radius equal to the cutter, so a rectangular pocket machined with a 6 mm cutter has 3 mm radius corners. A laser cuts a radius of about 0.15 mm, which reads as a sharp corner.
If a part needs a genuinely sharp internal corner in thick material, the answer is usually to machine it as two parts, to design a relief, or to accept the radius. A laser can cut the outline sharp but cannot machine a pocket in 20 mm sheet.
A laser-cut edge is glossy, because the beam vapour-polishes as it cuts, but it is not clear. Under a light it reads as a slightly milky band, and through the thickness it is tapered. On a display part the edge is often the most visible surface in the piece, and a laser edge does not look like a polished edge no matter how it is lit.
A routed edge is matte and square, and it takes a diamond polish to a water-clear finish. So the sequence for a display part is route, then polish. Cutting it on the laser and then polishing is possible, but the polishing takes longer because the tapered heat-affected edge has to be machined back first.
A practical rule from our own shop: if the edge will be polished, route it. If the edge will be hidden in a frame, laser it and save the money. The exception is thin sheet under about 3 mm, where the laser edge is good enough for many visible applications and the speed advantage is large.
Laser-cut holes are fast and cheap, and slightly tapered: a 5 mm hole cut in 8 mm sheet may measure 5.05 mm at the entry and 4.8 mm at the exit. For a clearance hole that does not matter. For a hole that takes a dowel, a pin or a bearing, it does.
Routed holes are parallel and can be held to ±0.05 mm with a reamer. For a hole that is a locating feature, always route and ream, and specify the fit.
A laser puts a lot of heat into a narrow zone. That leaves a heat-affected layer, a faint acrid smell that fades over days, and local stress at the cut. On a part that will be bonded or cleaned with solvent, that stress is a crazing risk, and the smell is an objection in a sealed case or a food display.
A router cuts cold. There is no heat-affected zone and no smell, but there is mechanical stress from the cutter, which is why a routed edge sometimes chips if the tool is blunt or the feed is wrong.
A DXF is ideal for a flat part: it carries the outline and all hole centres without ambiguity. Send the drawing with the material, thickness, which edges are visible, and any hole that is a locating feature marked as such. With that, we choose the process and tell you which one we used and why.
If the part has a bend or a 3D feature, send a STEP file so the geometry is explicit. A flat DXF cannot describe a folded part and will be misinterpreted.
Yes, but the heat-affected edge has to be machined back first, so polishing takes longer than on a routed edge. For a polished part it is usually cheaper to route from the start.
It leaves a heat-affected layer with local stress, which slightly reduces strength at the edge and increases the risk of crazing if the part is later solvent-bonded or cleaned aggressively. For most parts this is not significant; for a bonded or chemically exposed part, route instead.
About 25 mm on our machines, but quality falls off sharply above 12 mm, where the edge becomes visibly tapered and rough. Above 12 mm we route by default.
They are not oval, they are tapered: the beam diverges through the thickness so the hole is larger at the top than the bottom. A pin inserted in the hole rocks, which reads as oval. The fix is to route and ream any hole that has to be a fit.
The router, by a wide margin. A routed and diamond-polished edge on 20 mm acrylic is optically clear; a laser edge on the same material is glossy, tapered and slightly hazy.
Tell us which edges are seen and which holes are locating features, and we will cut it the cheaper way that still meets the drawing.