# How to Source CNC Machined Parts From China Without Surprises

Published 2026-09-16 by the Axisform engineering team. URL: https://www.machined-parts-factory.com/blog/source-cnc-machined-parts-from-china/

## Key takeaways
- Send a STEP model plus a toleranced PDF drawing with material grade, finish, quantities and inspection requirements.
- Approve a first article with a ballooned drawing and full measurement report before production, and keep a golden sample.
- Require dimensional reports, material certificates (often EN 10204 3.1) and a certificate of conformance as appropriate to the risk.
- FOB and CIF are sea-freight terms; for express and air shipments, FCA, DAP or DDP fit better.
- Agree packaging, revision control and non-conformance handling in writing before the first order.

To source CNC machined parts from China without quality surprises, send a complete RFQ package (3D model, toleranced 2D drawing, material, finish, quantities and inspection requirements), approve a first article with a dimensional report before production, require inspection reports and material certificates with each shipment, and agree on Incoterms and packaging in writing. Most quality problems come from information that was never written down, not from machine capability. The steps below make expectations explicit at each stage.

## Why do quality surprises happen with overseas suppliers?

Quality issues on imported machined parts usually trace back to a small number of causes:

- **Ambiguous drawings.** Missing tolerances, unclear finish specs or no note on whether dimensions apply before or after coating.
- **Assumptions about material.** "Aluminum" or "stainless" without a grade and temper.
- **No agreed inspection method.** The buyer measures with a CMM; the supplier measured with calipers.
- **Cosmetic expectations not defined.** Scratches, tool marks and color shifts that one side considers acceptable and the other does not.
- **Changes after approval.** A revision that never reached the shop floor, or a process change that was not communicated.

Each of these is preventable with documentation and a clear approval process.

## What should a complete RFQ package include?

A complete request for quotation gets you an accurate quote faster and prevents errors later.

1. **3D CAD model** in a neutral format such as STEP (preferred), IGES or Parasolid (X_T).
2. **2D drawing (PDF)** with tolerances, datums, GD&T, surface roughness, thread specifications and a general tolerance note such as ISO 2768-mK. The drawing, not the model, should be the controlling document for tolerances.
3. **Revision level** on every file, matching between model and drawing.
4. **Material** with grade and temper (for example "6061-T6," "304 stainless," "C36000 brass") and any required standard.
5. **Finish specification** with type, color, thickness and masking (for example "Anodize Type II Class 2, black, 10–15 µm, mask threads").
6. **Quantities**, ideally several tiers (for example prototype, pilot and production), so you understand how price scales.
7. **Critical-to-function dimensions** flagged on the drawing.
8. **Inspection and documentation requirements:** first article report, CMM report, material certificates, certificate of conformance.
9. **Cosmetic standard:** which surfaces are cosmetic, what defects are acceptable and at what viewing distance.
10. **Packaging and labeling requirements.**
11. **Target delivery date and preferred Incoterm.**

If your design is confidential, send a non-disclosure agreement before or with the RFQ.

### What questions should the supplier ask back?

A good supplier will return engineering questions (sometimes called an EQ or DFM review) before quoting or before production: conflicting dimensions, unachievable tolerances, finish allowances, thread callouts and material availability. Treat these questions as a sign of diligence. A supplier that quotes a complex drawing with no questions at all may not have read it closely.

## What is a first article inspection (FAI) and why does it matter?

A first article inspection is a full dimensional and documentation check of the first part(s) produced with the production process. It verifies that the process can make the part to the drawing before the full batch is run.

A useful FAI package contains:

- **A ballooned drawing** — every dimension and note numbered.
- **A measurement report** listing each balloon, the nominal, the tolerance, the measured value and pass/fail.
- **Material certificate** for the raw material lot.
- **Finish verification** — coating thickness, color comparison, salt spray or other test results if required.
- **Photos** of cosmetic surfaces.

Aerospace suppliers often use the AS9102 format, and automotive programs may require PPAP. For most industrial parts, a ballooned drawing with a complete measurement report is sufficient.

### Should you order samples before production?

For new parts, new suppliers or critical assemblies, yes. Order a small quantity of samples, test them in your assembly, and approve them in writing. Keep at least one approved sample as a "golden sample" for future reference, especially for cosmetic finishes and color.

## What inspection reports should you require?

Match the documentation to the risk of the part:

| Document | What it shows | When to require it |
|---|---|---|
| Dimensional inspection report | Measured values of critical or all dimensions | Every production shipment |
| CMM report | Coordinate measurement of complex features and GD&T | Tight positional tolerances, complex geometry |
| First article inspection (FAI) | Full report on first parts from a new or changed process | New parts, revisions, new suppliers |
| Material certificate (mill cert) | Chemical composition and mechanical properties of the raw material lot | Structural, safety-critical or regulated parts |
| Certificate of conformance (CoC) | Supplier statement that parts meet the drawing and PO | Most shipments |
| Finish/coating report | Coating thickness, adhesion or salt spray results | Functional coatings, outdoor parts |

Material certificates are often issued to EN 10204 type 3.1, which certifies test results for the specific lot.

### How do you sample a production lot?

For production lots, critical dimensions should be checked at 100% where practical, and other dimensions sampled. ISO 2859-1 (equivalent to ANSI/ASQ Z1.4) defines AQL sampling plans that let you inspect a statistically based sample size for a given lot size. State the AQL level in your purchase order or quality agreement if you need it. For high-risk parts, a third-party pre-shipment inspection is another option.

## Which Incoterms should you use?

Incoterms 2020 define who pays for transport, insurance and duties and where risk transfers from seller to buyer. The most common options for machined parts:

| Incoterm | Seller's responsibility | Buyer's responsibility | Notes |
|---|---|---|---|
| EXW (Ex Works) | Makes goods available at the factory | Everything from pickup, including export clearance | Most work for the buyer |
| FCA (Free Carrier) | Delivers to buyer's carrier, export-cleared | Main transport, import | Suits air freight and express |
| FOB (Free On Board) | Delivers onto the vessel at the port, export-cleared | Ocean freight, insurance, import | Sea freight only |
| CIF (Cost, Insurance and Freight) | Pays freight and minimum insurance to destination port | Import clearance, duties, delivery | Sea freight only; risk passes at loading |
| DAP (Delivered at Place) | Delivers to named destination | Import clearance and duties | Common for express |
| DDP (Delivered Duty Paid) | Delivers to destination including duties and import clearance | Unloading | Least work for the buyer |

FOB and CIF are designed for sea and inland waterway transport. For air freight and express courier shipments, FCA, CPT, CIP, DAP or DDP are more appropriate, although FOB is still used informally.

## How should machined parts be shipped from China?

- **Express courier** (DHL, FedEx, UPS) is the usual choice for prototypes, samples and small production lots. It is fast and door-to-door.
- **Air freight** suits larger, urgent production shipments.
- **Sea freight** is the most economical for heavy or high-volume shipments, with longer transit times.

### What about customs and duties?

The importer is responsible for classifying parts with the correct HS (Harmonized System) code and paying applicable duties. Tariff rates depend on the product classification, the destination country and current trade measures, and they change. Check current rates with your customs broker before committing to a landed cost. Provide the supplier with any specific invoice or labeling requirements in advance.

### How should parts be packed?

- Anodized and cosmetic parts: individual bags or foam separation to prevent rubbing.
- Steel parts: anti-rust oil or VCI (volatile corrosion inhibitor) packaging.
- Precision features: protective caps on threads and bores.
- Labels with part number, revision, quantity and lot number on each inner pack.
- Strong outer cartons, palletized for freight.

## How do you manage communication and revisions?

- **Name one engineering contact on each side.** This prevents conflicting instructions.
- **Control revisions.** Every drawing change gets a new revision letter, and the purchase order references the revision.
- **Write down approvals.** Email confirmation of sample approval, deviations and changes.
- **Agree on non-conformance handling** — how rejected parts are reported, with photos and measurements, and how rework or replacement is handled.
- **Allow for time zones.** A clear question sent at the end of your day can be answered by the start of your next working day.

## How does Axisform handle this process?

Axisform works under an ISO 9001 quality management system from its production base in Dongguan, Guangdong. Quotes are usually returned within 24 hours on business days. Each order typically includes first-article inspection, in-process checks and 100% inspection of critical dimensions before shipment; inspection reports and material certificates are available on request. Shipping is by DHL, FedEx, UPS, air or sea freight, with EXW, FOB, CIF or DDP terms by agreement. See [about us](/about/), our [projects](/projects/), or send your RFQ package through [contact](/contact/).

Before sending the RFQ, it is worth checking your design against our [DFM rules](/blog/dfm-rules-reduce-cnc-machining-cost/) and [tolerance guide](/blog/cnc-machining-tolerances-cost-guide/).

## Frequently asked questions

### What files should I send to get a CNC machining quote?

Send a 3D model in STEP format and a 2D PDF drawing with tolerances, material, finish and quantities. The 3D model defines geometry, while the drawing defines tolerances, threads, surface finish and inspection requirements.

### What is the difference between FAI and pre-shipment inspection?

A first article inspection checks the first parts from a new process against every drawing requirement before production. A pre-shipment inspection checks a finished production lot, usually by sampling, before it leaves the factory.

### Which Incoterm is best when buying from China?

It depends on how much logistics you want to manage. EXW and FOB give the buyer more control over freight; DDP gives the simplest delivery with duties included. For express and air shipments, FCA, DAP or DDP fit better than FOB or CIF.

### How can I verify the material used in my parts?

Request a material certificate (mill certificate) for the raw material lot, often to EN 10204 3.1. For critical parts, you can also have a sample tested independently, for example by spectrometer analysis.