CNC machining: tolerances, roughness and lead times
The complete reference table for CNC milling, turning and 5-axis machining at FormHub. These are the same values our automatic DFM check applies.
- CNC machining at FormHub works to ISO 2768-m by default. With fine machining we hold ±0.05 mm in milling and ±0.025 mm in turning, and ±0.01 mm is achievable after engineering review. Minimum wall thickness is 0.8 mm, the smallest hole 1.0 mm, and surface roughness ranges from Ra 0.2 to 3.2 µm.
Key specifications
- CNC Milling (3-axis) — tolerantie
- ISO 2768-m · fijn ±0.05 mm (fijnbewerking)
- CNC Milling (3-axis) — min wall / hole
- 0.8 / 1 mm
- CNC Turning — tolerantie
- ISO 2768-m · fijn ±0.025 mm (fijnbewerking)
- CNC Turning — min wall / hole
- 0.8 / 1 mm
- 5-Axis CNC Machining — tolerantie
- ISO 2768-m · fijn ±0.03 mm (fijnbewerking)
- 5-Axis CNC Machining — min wall / hole
- 0.8 / 1 mm
Frequently asked questions
- What does ISO 2768-m mean in practice?
- ISO 2768-m is the medium class for general tolerances. In practice it means roughly ±0.1 mm on dimensions up to 30 mm and ±0.2 mm up to 120 mm, plus the associated angular and form tolerances. You therefore do not need to individually tolerance those dimensions.
- When should I specify a tighter tolerance?
- Only on functional surfaces: bearing and shaft fits, sealing faces, alignment and datum holes. Every tighter tolerance adds machine time and inspection — ±0.05 mm adds about 30%, ±0.01 mm about 80%.
- How fast can a rush order be delivered?
- The table above shows our normal turnaround. For rush work we switch to a partner with free capacity; 3 working days for a small batch is usually achievable. State your deadline in the request and we confirm feasibility before you order.