Note on painted sheet

Laser-cutting painted sheet.
This is what happens at the edge.

When painted or powder-coated sheet is laser-cut, the cut edge is not completely clean. The heat of the laser burns the paint at the edge, and sometimes it also chips off. Straight cuts on the guillotine shear are not affected: no heat is produced there, so the paint does not burn. For laser-cut contours there are two proven ways to a clean edge.

Plan a clean edge → All surface finishes →

What you see at the laser-cut edge

Burnt paint
The laser separates the sheet with heat. Right at the edge the paint burns on a narrow strip and turns it dark.
Chipped paint
Sometimes the coating chips off at the edge in small pieces, revealing the bare metal underneath.
Flawless surface
Away from the edge the surface keeps its full coating and colour.

Examples from our workshop

White painted sheet with a laser-cut round edge and a dark strip — Laser-cut, RAL 9016: the heat has burnt the paint at the round edge.

Close-up of a laser-cut edge on white painted sheet — Close-up: a burnt, slightly jagged strip of paint right at the edge. The surface stays pure white.

Anthracite painted sheet with protective film, paint chipped at the edge — RAL 7016 with protective film: the paint has chipped off on a narrow strip at the edge.

Corner of an anthracite painted part with protective film — Corner of a part: the surface stays protected and flawless under the film.

With or without protective film?

Aluminium painted RAL 7016 is laser-cut with or without protective film, as you choose. You choose in the part designer or in the basket; the price is the same.

StandardWith protective filmThe surface stays protected during cutting and transport. At the cut edge, however, the coating clearly chips off.

For visible edgesWithout protective filmA much cleaner cut edge without chipping. The surface is then unprotected. Please handle the part with care; slight marks from transport are possible.

Anthracite painted aluminium sheet with protective film, laser-cut edge with clearly chipped paint coating — With protective film: the surface lies protected under the film. At the cut edge the paint coating has clearly chipped off and the rim is irregular.

Corner of an anthracite painted aluminium part with a radius, laser-cut without protective film — Without protective film: corner with a radius. The edge runs evenly and clearly, without chipping.

Rounded corner of an anthracite painted aluminium part, laser-cut without protective film — Without protective film: the curve is even. A narrow bare metal rim shows at the edge.

Straight edge and radius of an anthracite painted aluminium part, laser-cut without protective film — Without protective film: straight edge and radius with a clean, even finish.

Ways to a clean edge

Straight partsCut-to-size on the guillotine shearThe shear separates the sheet without heat. The paint does not burn. Ideal for rectangles and straight edges, also as a bent part.

Always possibleCut bare, coat afterwardsWe laser-cut the part from uncoated sheet. You then have it painted or powder-coated. This way the edge is fully coated as well.

Without heatPunching and nibblingThe tool separates the sheet mechanically, so the paint does not burn. Contours that can be made with our punching tools are possible. More on this under Punch-laser combination.

We are happy to check whether your part can be punched. Simply send us your drawing as a review request.

How the edge looks clean on the finished part

Place the edge on the inside. Plan the part so that cut edges are on the inside, underneath or against the wall after installation.
Fold the edge over. On a bent part , a hem (fold) covers the cut edge. The painted side stays on the outside.
Cover the edge. An edge trim, a seal or an edge protector gives a clear, even finish.
Touch up the edge. With a touch-up pen in the matching RAL colour you close the strip in a few minutes. Outdoors this also seals the edge.
Keep the film on until the end. Only peel off the protective film after installation. This keeps the surface flawless.

Frequently asked questions

Which sheets are affected?

All painted and coated sheets: powder-coated, stove-enamelled, wet-painted and coil-coated, for example Aluminium painted RAL 9016 and RAL 7016.

Does this also happen when cutting on the guillotine shear?

No. The guillotine shear separates the sheet without heat, so the paint does not burn there. Straight cut pieces and bent parts made from them get an edge without burn marks.

Why does the paint burn during laser cutting?

The laser melts the metal along the cutting line. This heat also reaches the paint right next to it, which burns there and can chip off.

Should I order with or without protective film?

With protective film the surface stays protected during cutting and transport, but the paint coating chips off noticeably at the cut edge. Without protective film the cut edge is much cleaner and free of chipping, but the surface is then unprotected. If the edge will be visible, choose “Without protective film”; if an untouched surface matters most, choose “With protective film”. The price is the same in both cases.

Is this a defect?

No. The burnt edge occurs with every laser cut of painted sheet and reflects the state of the art. The surface of the part has the full coating.

Can every part be punched?

Contours made of shapes for which punching tools exist are well suited to punching and nibbling. We are happy to check your part and recommend the right way.

Does the edge last outdoors?

Aluminium forms a protective oxide layer on the bare edge. For an even look and extra protection, seal the edge with a touch-up pen.

Your part with a clean edge

Straight cut-to-size on the guillotine shear → Draw or upload a part → Punching and nibbling → Bent part with hem →

Laser-cutting painted sheet.This is what happens at the edge.