What sets the kerf
The kerf is barely wider than the focused beam, and the focal diameter sets its width and form (TRUMPF). It grows with thickness, and it depends on the material, the laser power, the cutting speed and the gas (Xometry).
Published ranges therefore differ: 0.1 to 1.0 mm in general (Xometry), about 0.008 in (0.2 mm) on Xometry's sheet cutting page, 0.152 to 1 mm on SendCutSend's fibre lasers depending on thickness, 0.1 to 0.3 mm on fibre lasers (TAUPITZ), 0.1 to 0.3 mm for thin sheet and up to 0.5 mm for thicker material (MEILLER), 0.1 to 0.8 mm for laser oxygen cutting depending on thickness (German Wikipedia), and as small as 0.10 mm depending on thickness (English Wikipedia).
Shops disagree on who compensates. SendCutSend offsets the path on the machine and warns that if you compensate yourself, the part is likely to end up outside your tolerances; Xometry states that its typical tolerance of ± 0.010 in includes compensation for kerf. MEILLER writes that the kerf must be taken into account in the design to ensure an exact fit, and TAUPITZ asks designers of slot-and-tab fits to include it in the tolerance calculation and to ask the shop for the exact value, because a clearance of zero does not work in practice.
Worked example: kerf and cut length
The analyzer's example plate: 100 × 50 mm with one hole of 20 mm. CutMeter measures 362.83 mm of cut and 2 pierces: the length of the drawn contours.
With a kerf of 0.2 mm the beam's centre runs 0.1 mm outside the outer contour and 0.1 mm inside the hole. Offsetting with round corners makes the outer path 0.63 mm longer (π × kerf) and the hole's path 0.63 mm shorter.
For this plate the two changes cancel out: the path is as long as the drawing. In general each outer contour adds π × kerf and each hole subtracts it, a fraction of a millimetre per contour, so the drawn length is the honest basis for a price.
Published kerf ranges
| Source | Kerf |
|---|---|
| Xometry, laser cutting rules | 0.1 to 1.0 mm |
| Xometry, sheet cutting | about 0.008 in (0.2 mm) |
| SendCutSend, fibre laser | 0.006 to 0.040 in (0.152 to 1 mm) depending on thickness |
| TAUPITZ, fibre laser | 0.1 to 0.3 mm |
| MEILLER | 0.1 to 0.3 mm for thin sheet, up to 0.5 mm for thicker material |
| Wikipedia (de), laser oxygen cutting | about 0.1 to 0.8 mm |
| Wikipedia (en), laser cutting | as small as 0.10 mm |
| TRUMPF | barely wider than the focused beam, often under 0.5 mm in diameter |
Measure the cut length of a DXF
Questions
What is kerf?
The width of the material the beam removes: the slot left between the part and the sheet.
Should I compensate for kerf in my drawing?
Ask your shop first. SendCutSend and Xometry compensate in the cutting program and expect the nominal geometry; MEILLER asks to take the kerf into account in the design. Never compensate twice: once in the drawing and again on the machine.
How do I design a slot-and-tab fit?
Plan a clearance, ask the shop for its kerf value in your material and thickness, and include it in the tolerance calculation. A clearance of zero does not work in practice (TAUPITZ).
Does kerf change the cut length in my quote?
Hardly. With round corners each outer contour gets π × kerf longer and each hole π × kerf shorter, a fraction of a millimetre per contour. CutMeter prices the drawn length.
Is the kerf wider in thick sheet?
The published ranges grow with thickness: German Wikipedia gives about 0.1 to 0.8 mm for laser oxygen cutting depending on sheet thickness. Material, laser power, cutting speed and gas change it too (Xometry).
Sources
- Xometry: Laser Cutting and Designing: Guidelines, Rules, and Safety Tips xometry.com
- Xometry: Custom Sheet Cutting Service xometry.com
- SendCutSend: What Is Kerf in Laser Cutting? sendcutsend.com
- TAUPITZ: Schlitz-Steck-Verbindungen ohne Spannvorrichtung konstruieren (German) taupitz.com
- MEILLER: Ratgeber zu Lasertoleranzen (German) meiller-lasertechnik.de
- Wikipedia: Laserschneiden (German) de.wikipedia.org
- Wikipedia: Laser cutting en.wikipedia.org
- TRUMPF: Laser cutting trumpf.com