Guide
Laser cutting: what the process holds, what it does to the edge, and what to draw
Most sheet metal parts start on a fiber laser. The laser cuts a profile from flat stock with a beam a few thousandths wide, with an edge, an accuracy and a few side effects that are the same across shops because they come from the physics of the process. Knowing them tells you what to put on the drawing and what not to expect from a cut edge.
Send a drawingUpdated October 8, 2026
Kerf
The kerf is the width of material the beam removes, typically a few thousandths of an inch on thin sheet and more on thick plate. The shop's program offsets the cut path by half the kerf so the part comes out to the drawn profile. You do not account for kerf on the drawing; you draw the finished part. What kerf does mean is that very narrow slots and very small holes have a floor: a hole smaller than about the material thickness is usually drilled after cutting rather than lasered, and the quote says so.
Accuracy
A fiber laser holds the position of a cut profile to a few thousandths across a typical part, and the hole-to-hole positions on a flat blank are good because they come from one program on one sheet. The edge itself is not a machined edge: it carries a slight taper through the thickness, a striation pattern, and on thicker steel a hard, recast layer that a tap or a reamer will notice. A laser-cut hole that must take a close-fitting pin is drilled or reamed after cutting.
The numbers that matter are the shop's and are on its quote for your part. The process gives most shops a comparable band; the quote is where it is stated for the thickness and the material you drew.
Edge quality by material
| Material | Cutting gas | Edge | Notes |
|---|---|---|---|
| Mild steel | Oxygen | Oxide film, slight dross on thick plate | Oxide is removed before powder coat; nitrogen cutting gives a bare edge at a higher cost |
| Stainless | Nitrogen | Bright, oxide-free | Preferred for food and pharma; the edge is weldable as cut |
| Aluminum | Nitrogen | Clean with a small burr on thick sheet | Reflective; thin sheet cuts well, very thick plate is a waterjet or saw job |
| Galvanized | Oxygen or nitrogen | Zinc burns back from the edge | Call out an edge treatment if corrosion at the edge matters |
Heat and flatness
The laser puts heat into the sheet along the cut. On thin sheet with a lot of cutting, or long thin parts, that heat can bow the part. Shops manage it with cut order and nesting, and a part that must be flat after cutting should say so with a flatness callout; a part with a long thin bridge should be redesigned or expect to be straightened.
What to put on the drawing
- Material and thickness, and whether the oxide edge is acceptable on steel (it is, under powder coat; it is not, for a weld prep that needs a clean face).
- Which holes are clearance and which must be drilled, tapped or reamed after cutting.
- Edge condition where it matters: deburr, break sharp edges, or a cosmetic edge on a visible part.
- Flatness if the part is a flat plate that must sit flat.
Questions buyers ask
- Laser or waterjet?
- Laser for sheet and plate up to the shop's thickness limit, and for speed. Waterjet for thick plate, heat-sensitive materials, and stacked cutting. Many shops run both; draw the part and let the quote say which.
- Can the laser cut threads?
- No. It cuts the tap drill hole, and the shop taps after. Call the thread out as a thread; the shop sizes the hole.
- Do I need to send a DXF?
- For a flat part a DXF or a STEP lets the shop program from your geometry instead of redrawing it, which removes a source of error. A PDF alone works but the shop traces it.
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