Laser Cutting Acrylic: Edges, Thickness and CNC

Laser Cutting Acrylic: How It Works

Laser cutting acrylic uses a focused CO2 laser beam to vaporize PMMA along a vector path. Acrylic strongly absorbs the CO2 laser’s 10.6 µm wavelength, so the beam cuts flat profiles with a narrow kerf and, at the right power and speed, leaves a smooth, clear edge that often needs no polishing. It cannot cut pockets, chamfers or counterbores; that is CNC work. Cutting is one step of acrylic fabrication; the rest of the route is decided in the same quote.

The beam melts a very thin layer at the cut face as it passes. That melted layer re-solidifies glossy, which is why laser-cut acrylic edges are often called “flame polished.” Epilog, a US laser manufacturer, describes the right combination of speed, power and frequency as leaving the edge “crystal clear and perfectly smooth”¹.

We run 8 laser cutters and 4 CNC machines under one roof. If you already have a drawing, our acrylic laser cutting service page covers files, samples and production; parts that need pockets, bores or thick-stock geometry go through acrylic CNC machining.

A few practical points buyers ask about:

• Clear acrylic needs a CO2 laser. Clear sheet passes visible light, which is why low-power blue diode lasers struggle to cut it. Production shops cut acrylic on CO2 machines.
• Fumes need extraction. Epilog warns that vaporized acrylic produces strong fumes and fine particles and should never be cut without proper ventilation¹.
• Engraving and cutting happen on the same machine. A laser can mark a logo or part number and cut the outline in one setup, which is why laser-cut parts are common for signs, inserts and display panels.

What Thickness Can a Laser Cut in Acrylic?

Cutting depth depends on laser power. Epilog’s published guide lists 1/8 in (about 3 mm) on a 30–40 W laser, 1/4 in (about 6 mm) on 50–60 W, 3/8 in (about 9.5 mm) on 80–100 W, 1/2 in (about 12.7 mm) on 120 W and 3/4 in (about 19 mm) on 200 W in a single pass¹.

Two things change as the sheet gets thicker. The cut slows, and the edge can show a slight taper and heat marks. Most display, sign and insert work sits in 2–10 mm sheet, which is where laser cutting acrylic is most efficient. For thick blocks and bases, I normally route the part on CNC and polish the edge instead. Our acrylic thickness guide covers how to choose the sheet in the first place.

Laser-Cut Acrylic Edge Quality

A well-tuned laser leaves a glossy, clear edge on acrylic with no separate polishing step. A CNC-routed edge is matte and is diamond or flame polished if it shows. The laser edge is not perfectly square on thick sheet and carries heat stress, so it may not suit parts that will be solvent bonded.

Sheet type matters too. Epilog notes that extruded acrylic cuts cleanly with a flame-polished edge, while cast acrylic engraves to a frosty white, which makes cast the usual choice for engraved logos¹. Sheet producers such as Plaskolite document the thermal and cutting behavior of cast and extruded PMMA by grade and thickness², and our cast vs extruded acrylic guide explains the difference in more detail.

What I look for when a buyer says “the edges must look perfect”:

Edge requirement	Usual route
Visible perimeter on flat sheet, gloss is fine	Laser cut, no polish
Mirror-flat, square edge on thick sheet or blocks	CNC route, then diamond polish
Tight inside curves that must be clear	Laser cut, or CNC plus flame polish
Edge that will be solvent bonded	Review on the sample; heat-stressed edges can craze
Hidden edge (inside a frame or base)	Either route, no polish

For side-by-side edge photos and defects to watch for, see our acrylic edge finish reference and diamond vs flame polishing acrylic. How we check the finished edge against the approved sample is set out in our edge finish standard. Across plastics fabrication, visible finish inconsistency, cloudiness and dimensional variation at the edge are among the most common reasons parts are rejected; correct process selection and machine calibration are the upstream controls, and polishing is a correction, not a substitute.

Kerf, Tolerance and File Setup

Kerf is the width of material the beam removes. Cut Laser Cut, a UK laser-cutting service, publishes acrylic kerf of about 0.18 mm on 1–3 mm sheet, 0.21 mm on 5–8 mm, 0.30 mm on 10–15 mm and 0.32 mm on 20 mm³. The cutting program compensates for it, so your drawing should show finished dimensions.

Acrylic thickness	Typical kerf
1–3 mm	about 0.18 mm
5–8 mm	about 0.21 mm
10–15 mm	about 0.30 mm
20 mm	about 0.32 mm

Our standard working tolerance is ±0.2 mm. Fit-critical 2D dimensions, such as slots that take a mating panel, can be held to ±0.1 mm after drawing review; mark them on the drawing so they are measured at inspection. Our tolerance standard explains how each class is checked.

File setup decides most first-sample problems. Send a vector file (DXF, AI or vector PDF) at 1:1 scale with one revision, plus a dimensioned PDF. Our CAD files for custom acrylic parts guide lists the common file errors.

When CNC Routing Is the Better Route

Choose CNC routing when the part needs anything a beam cannot do from above: pockets, chamfers, counterbores, stepped faces, controlled bores, or cuts in stock thicker than the laser handles well. Choose laser cutting acrylic for flat through-cut profiles in sheet, where the clear as-cut edge saves a polishing step.

Factor	Laser cutting acrylic	CNC routing acrylic
How it cuts	CO2 beam vaporizes the cut line	Spinning carbide or diamond tool mills material
Edge as cut	Glossy and clear on a tuned cut	Matte with tool marks
Polishing	Often none on visible edges	Diamond or flame polish if the edge shows
Features	Through-cuts, engraving	Pockets, chamfers, counterbores, steps, bores
Inside corners	Nearly sharp, limited by kerf	At least the tool radius
Thick stock	Slows and tapers near the power limit	Handles thick sheet and blocks
Heat	Heat-stressed edge	No heat edge; mechanical stress from tooling

Many products use both. A retail display may have laser-cut shelves and sign panels on a CNC-routed thick base with pockets for magnets. In our CNC base program for a German OEM, the bases were machined, while projects such as our custom packaging inserts were laser cut from sheet. The quote should name the process and edge finish for each part.

Ordering Laser-Cut Acrylic Parts

The price of a laser-cut part is set mainly by sheet grade and thickness, total cut length, how many parts nest on one sheet, any engraving or printing, and whether an edge needs polishing. Quantity lowers the unit price because more parts share the setup and the sheet.

For custom production we work from 100 pieces per design. Paid samples take 3–5 days and cost USD 200–500 depending on complexity; the fee is paid separately and never credited to the production order. Production runs 15–20 days after sample approval, FOB Shenzhen by default. For display parts, see our acrylic display stands; for card-shop fixtures, the trading card display application lists the fit questions to supply. The full range of cutting and finishing options is on our custom acrylic fabrication page.

When I review a laser RFQ, the first thing I look for is which edges show. That one detail decides whether a part can ship as cut or needs a polishing step, and it changes the quote. Send the file, quantity and visible-edge notes to inquiry@wetopacrylic.com, and we reply within 24 hours with the cutting route and edge finish named for each part.

Footnotes

1. Epilog Laser — Laser Cutting and Engraving Acrylic — laser manufacturer’s application guide; source for the single-pass thickness by wattage table, the cast vs extruded behavior (extruded cuts with a flame-polished edge, cast engraves frosty white), the clear-edge settings, and the fume and ventilation warning. ↩ ↩² ↩³ ↩⁴

2. Plaskolite PMMA technical resources — US-based acrylic sheet manufacturer; their technical library documents cast and extruded PMMA thermal properties, cutting behavior, and thickness-specific fabrication guidance that informs our process parameter selection. ↩

3. Cut Laser Cut — Laser Kerf — UK laser-cutting service’s measured kerf table by material and thickness; source for the acrylic kerf values from 0.18 mm on 1–3 mm sheet to 0.32 mm on 20 mm. ↩