Laser cutting does not have one universal tolerance. Material, thickness, geometry, thermal behavior, machine condition and inspection method all affect the finished part.
Kerf compensation is not a tolerance guarantee
Kerf is material removed along the cut. CAM offsets the path to account for its expected width, but variation in kerf, focus, motion and thermal conditions remains. A correct nominal offset can still produce out-of-tolerance features.
A hole and an outside contour require opposite offset senses. If a nominal 10 mm hole measures 9.8 mm, first verify whether the discrepancy comes from path compensation, taper, dross or measurement location. Increasing an offset blindly may hide a different process problem.
| Feature / measurement | Useful inspection definition |
|---|---|
| Hole diameter | Top, bottom or specified section; burr treatment |
| Edge-to-edge size | Datums and measurement temperature |
| Hole position | Defined coordinate system / datum references |
| Cut-edge taper | Difference between sections through thickness |
| Flatness | Free-state or restrained condition |
| Small slot | Minimum opening and allowed corner shape |
Separate size, position and edge quality
A circular hole can have acceptable average diameter but incorrect position. A profile can meet its top-surface dimensions while having unacceptable edge taper. Burrs and dross can interfere with assembly even if the cut path was located correctly. Specify the characteristics that affect function rather than asking only for “high precision.”
For a tab-and-slot assembly, evaluate both tab width and slot width, including their tolerances and any coating. A nominal 0.2 mm gap is not guaranteed if the two feature tolerances can consume it.
Agree on capability for the actual job
Provide material grade, thickness, CAD revision, critical features and required edge condition. Ask the selected supplier for capability under those conditions, and approve a representative first article where appropriate. Supplier tolerance guides are scoped to their equipment and processes.
Use measured results to refine compensation and process settings, with controlled revisions. Do not publish a single tolerance as a promise for every material and thickness. The kerf calculator illustrates geometry, while process qualification establishes actual capability.
Example: a tab fits at the top but binds below
Consider a hypothetical drawing with a tab width of 10.00 ±0.10 mm and a mating slot of 10.30 ±0.10 mm. Before coatings, minimum width clearance is 10.20 − 10.10 = 0.10 mm; maximum is 10.40 − 9.90 = 0.50 mm. Those are specified design limits, not laser-process capability claims.
If both tab edges and both slot walls receive a uniform 0.02 mm coating, the tab widens by 0.04 mm and the slot narrows by 0.04 mm. Minimum clearance falls to 0.02 mm. A burr or local taper may consume that remainder. A nominal 0.30 mm CAD gap is therefore not the complete fit analysis.
| First-article check | Record |
|---|---|
| Tab width | Maximum retained width at the functional section |
| Slot opening | Minimum opening through the engagement depth |
| Cut-edge taper | Top and bottom readings with location identified |
| Burr treatment | As-cut, deburred or coated condition |
| Assembly | Actual mating part and defined insertion requirement |
Record repeated measurements across the nest rather than only one convenient edge. A nearly uniform size offset may justify investigating compensation; variation by location or through thickness calls for a process investigation. Do not adjust kerf to conceal taper, dross or measuring over a burr.
Supplier capability must be quoted for the actual job. For context, Protolabs separates same-surface and formed-feature tolerances by sheet thickness; these are its service guidelines, not a universal laser specification. Ask the chosen supplier which limits apply to your drawing and final surface condition.
Content updated October 8, 2026. Sources and numerical examples are explained above; examples are not production test results. Editorial method · Report a correction.
References and verification
Original explanations and worked examples by MfgWorkbench. Sources below support the stated concepts or selected reference data; they do not certify every example or a production application.
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