Reference Chart
CNC Machining Tolerance Chart and Review Levels
Use this chart for early quotation screening, not as a universal production guarantee. The following screening general metal tolerance is approximately ±0.10 mm, suitable precision features may be around ±0.05 mm, and qualified dimensions may reach approximately ±0.01 mm after geometry, material and measurement review.
Provisional Tolerance Levels
| Level | Screening value | Typical use | Required action |
|---|---|---|---|
| Unspecified dimensions | ISO 2768-m | Noncritical dimensions | Confirm internal standard before launch |
| General metal | Approx. ±0.10 mm | Suitable common features | Check size and geometry |
| General plastic | Approx. ±0.10–0.20 mm | Stable conditioned features | Define material and state |
| Precision | Approx. ±0.05 mm | Selected functional features | Process/inspection review |
| Tight qualified | Down to approx. ±0.01 mm | Specific dimensions only | Engineering/metrology approval |
| Beyond standard | Tighter than ±0.01 mm | Specialized requirement | No promise without study |
Factors That Change Capability
- Overall and feature size
- Material, hardness and stock condition
- Thin walls and distortion
- Heat treatment and coating
- Datum and setup relationships
- Measurement method and uncertainty
Geometric Tolerances Need Separate Review
Flatness, position, profile, runout, parallelism and perpendicularity cannot be inferred from a plus/minus chart. They require functional datums and suitable inspection.
Do Not Copy One Number Across the Drawing
Concentrate tight tolerances on interfaces that control fit or function. Use general tolerances elsewhere to reduce process and inspection cost.
Plastic and Flexible Parts
State free, restrained or assembled measurement, temperature and conditioning. A flexible part can change after unclamping or moisture exposure.
Standards and Regulatory Sources Used on This Page
For CNC Machining Tolerance Chart and Review Levels, these primary sources define the scope of cited standards or regulations. They do not prove Formexi certification, a customer approval or project compliance; those require current, scope-matched records.
How We Reduce Sourcing and Manufacturing Risk for CNC Machining Tolerance Chart and Review Levels
The purchasing issue behind CNC Machining Tolerance Chart and Review Levels is that ambiguous datums or blanket tight tolerances make machining and inspection plans disagree; as a result, the buyer can pay for unnecessary precision yet still receive results that do not predict fit, seal or motion. Our response is to maps each critical characteristic to a manufacturable datum scheme, process stage and accessible measurement method with suitable uncertainty. The objective is to protect assembly and validation schedules while reducing preventable scrap, rework and supplier-change risk.
For the CNC Machining Tolerance Chart and Review Levels buying decision, before we confirm price or delivery, the buyer should send the controlled 2D drawing, datum sequence, functional interfaces, tolerance standard, measurement condition and required report. If a requirement cannot yet be verified, we keep it as an open condition instead of presenting it as a guaranteed result.