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Precision CNC parts, tolerance stated before the cut
3-, 4- and 5-axis milling plus turning for metals and engineering plastics, held to ±0.005 mm where the drawing allows — with a FAI report and material certificate on every batch.
What tolerance can CNC machining hold?
The table below is how we answer that question in writing. Match your drawing to a row and you know which operation and which inspection method applies.
| Feature | Tolerance | How it is achieved | How it is verified |
|---|---|---|---|
| General dimension | ±0.05 mm | 3-axis milling, standard setup | Caliper and micrometer |
| Critical dimension | ±0.01 mm | 4-axis, single fixturing | CMM, 5 points per feature |
| Precision fit / bore | ±0.005 mm | 5-axis or jig bore, climate-controlled room | CMM and pin gauge |
| Flatness / parallelism | 0.01 mm | Ground after milling | Surface plate and indicator |
| Position (true position) | ⌀ 0.02 mm | Single datum, no re-chuck | CMM with stated datum scheme |
| Surface roughness | Ra 0.4 µm | Fine finishing pass or grinding | Profilometer, sampled per batch |
Tighter than ±0.005 mm is possible on request. It means grinding, a dedicated fixture and a longer lead time — we quote it as a separate line so the cost is visible.
Machine envelope and materials
| Processes | 3-axis, 4-axis, 5-axis milling; CNC turning; surface and cylindrical grinding; wire EDM |
|---|---|
| Max part size (milling) | 1,000 × 600 × 500 mm |
| Max turned diameter | ⌀ 320 × 600 mm |
| Metals | Aluminium 6061 / 7075, 45# carbon steel, 304 / 316 stainless, 718H, brass, copper, titanium (on request) |
| Plastics | POM, ABS, PC, PA6 / PA66, PEEK, PTFE, PMMA |
| Batch size | 1 part to 5,000 parts |
| Lead time | 5–12 days for typical batches |
Surface finish options
| Finish | Effect | Typical use |
|---|---|---|
| As machined | Visible tool marks, Ra 1.6–3.2 | Internal parts, fixtures |
| Fine machined | Smooth, Ra 0.8–1.6 | Mold inserts before polish |
| Anodised | Hard oxide layer, colour options | Aluminium housings, visible brackets |
| Bead blast | Matte, uniform texture | Cosmetic parts, tooling |
| Passivation | Corrosion resistance on stainless | Medical and food-contact parts |
| Heat treatment | Hardening to 48–52 HRC | Wear parts, mold inserts |
Production flow for a machined batch
- Drawing reviewDay 1
We check datum scheme, tolerance stack and whether the stated tolerance is reachable on the stated geometry.
- Programming and fixtureDay 1–2
CAM program plus a soft jaw or plate fixture so critical features are cut in one setup.
- First articleDay 2–4
One part cut, measured in full and sent to you with photos before the batch runs.
- Batch machiningDay 4–9
In-process checks at a fixed interval per operation, logged against the batch number.
- Inspection and packingDay 9–12
FAI report, CMM report for critical features, material certificate, then individually packed parts.
Records that ship with every batch
- Mill certificate for the stock used, matched to the batch number
- First article inspection report against your drawing
- CMM report with the datum scheme stated, where critical features are called out
- Surface roughness reading for cosmetic or sealing surfaces
- Photos of the finished parts before packing
CNC machining FAQ
What tolerance can CNC machining hold?
On a milled or turned metal part we hold ±0.005 mm on critical features and ±0.05 mm on general features as an ISO 2768-m default. Anything tighter than 0.005 mm needs a grinding operation and a stated datum scheme, which we quote as a separate line item.
How many parts can you machine per order?
Production runs typically sit between 1 and 5,000 parts. A single prototype is fine; above roughly 5,000 parts we will tell you when injection molding or casting becomes the cheaper route.
Do you provide material certificates for machined parts?
Yes. Every batch ships with the mill certificate for the stock used and a first article inspection report, plus a CMM dimensional report when the drawing calls out critical features.
Can you machine parts from our own stock material?
Yes. Send the material or arrange delivery to our Dongguan address and we will machine to your drawing. We photograph the incoming stock and record its condition before cutting.
What file formats do you accept?
STEP, IGES, X_T and Parasolid for 3D; PDF for 2D drawings. A native drawing with datums and tolerance callouts removes the guesswork that causes rework.
Send a drawing, get tolerance confirmation and a price
We reply within one business day with a feasibility note, a line-item quote and a batch lead time.
Request a quote