中国 CNC 加工サプライヤーの選び方（インサイダーガイド 2026）

When sourcing from China makes sense — and when it doesn’t

Real factory vs. broker — the telltale signs

About 60% of suppliers presenting themselves as “Chinese CNC factories” on Alibaba, Made-in-China, and similar platforms are actually trading companies (brokers) who outsource the work. They aren’t evil — many add real value — but the markup is 20–40% and you lose direct technical communication.

The 4-point verification framework

Before placing a meaningful order, verify each of these four things against independent evidence — not just the supplier’s claims:

1. 1

   1. Certifications with auditable IDs

   Ask for ISO 9001, AS9100, ISO 13485, IATF 16949 certificate copies including the certificate number. Verify each on the issuing body’s public database (e.g. SGS, BV, TÜV, DNV). A real cert lists the audited site address and scope. Mismatches = walk.

2. 2

   2. Equipment list with make, model and year

   A real factory can list specific machines: “Mazak Variaxis i-700 (2022), Haas VF-2 (2019), DMG Mori NLX 2500 (2021)”. Vague answers (“5-axis machining centres”) suggest they don’t actually own the equipment. Ask for serial numbers if quality is critical.

3. 3

   3. Capacity — floor space, headcount, current utilisation

   Reasonable answer: “3,200 m² floor, 65 staff including 8 engineers and 24 machinists, currently running 70% capacity.” Round-number bragging (“1000+ employees, 100,000 m²”) is usually a red flag — that scale of factory doesn’t do small-batch precision work.

4. 4

   4. References from previous customers in your industry

   Real factories have customers willing to talk. Ask for 2–3 reference customers, ideally in your industry, who have placed orders in the last 12 months. Call them or LinkedIn-message them directly — don’t rely on the supplier-provided testimonial PDF.

The 15-minute video walkthrough script

A 15-minute live video walkthrough beats any marketing deck. Schedule one before any meaningful order. Insist on live, not pre-recorded — and request specific things. Use this script:

1. Show the front gate with the company name visible. Confirms the address matches the certificate.
2. Walk through the production floor. Count machines. Look for tidiness, lighting, organisation. A messy shop produces messy parts.
3. Stop at 2-3 machines and read off the make/model on the nameplate. Cross-check with the equipment list provided earlier.
4. Show the metrology room. Real factories have a temperature-controlled CMM room. If they don’t have CMM, they can’t hold tight tolerances.
5. Show raw material storage with labels. Tags should reference Material Test Reports (MTRs) traceable to bar stock heat lots.
6. Show the QC area and any inspection in progress. Operators should be doing first-piece inspection on actual customer parts.
7. Ask to see a recent inspection report. Even if for a different customer (with sensitive data redacted). Confirms QC is actually documented.
8. Walk through the packing/shipping area. Should look like an outbound logistics zone, not a few boxes in a corner.
9. Ask to meet the engineer who would handle your job. If they hesitate or only the salesperson is available, that’s a flag.

How to read an RFQ response

The response to your RFQ tells you more than the price. Compare the responses you get against this checklist:

Protecting your IP and drawings

• Sign an NDA before sending detailed drawings. Use a basic mutual NDA — your supplier should have one, or use a template. Insist on a signed copy before sending STEP files.
• Watermark every drawing with your company name, date, and a confidentiality notice. Discourages casual leaks.
• Use generic feature names in CAD files rather than internal model numbers when possible. “Bracket-A” not “Sensor-Module-XR-2026”.
• Don’t share assemblies if you only need one part. Send only the file you need quoted, not the parent assembly with surrounding context.
• Register critical IP in China. If your part has a patentable design, register it in China — Chinese courts respect Chinese-registered IP, less so foreign-only registrations.
• Build a long-term relationship. Reputation matters in China. A factory with repeat customers is unlikely to risk that for one part’s IP.
• Split critical parts across two suppliers where possible. Prevents any single supplier from having the complete picture.

Payment terms that protect both sides

Standard Chinese CNC supplier terms vary by relationship maturity:

• Use a Letter of Credit (LC) for large orders. Bank guarantees both sides. Costs 1–3% but worth it for orders >$50k.
• Pay via wire transfer (TT) to a corporate account. Never to a personal account. Account name should match the supplier company name on invoice.
• Avoid PayPal or Western Union. Used by scammers because of irreversibility and informal nature. A real factory takes wire transfer.
• Hold final payment until quality acceptance. Specify acceptance criteria in the PO so “final QC” isn’t ambiguous.
• Hedge currency for large multi-month orders. RMB-USD can swing 5% in 6 months. For orders >$25k, consider a currency forward contract.

Red flags — when to walk away

• Refuses live video walkthrough. The single biggest red flag. Real factories with nothing to hide will accommodate.
• Won’t name specific equipment. “CNC machining centres” without makes/models = doesn’t own them.
• Wire transfer to personal account. Always to corporate account matching the company name on the invoice.
• Pricing 30%+ below other quotes. Either margin sacrifice they can’t sustain (you’ll get rushed work) or they don’t understand the spec.
• Lead time always “1 week” regardless of complexity. They’re telling you what you want to hear, not the truth.
• No certificates or only photocopies of expired ones. Verify on the issuing body’s database — current certs only.
• Pressure to sign the same day. Real factories accommodate proper due diligence; pushy ones are usually brokers worried you’ll find a better deal.
• Inconsistent details across emails. Address says one thing, certificate says another, equipment list contradicts. Likely multiple people pretending to be one factory.
• Won’t share customer references. Either no real customers or those customers wouldn’t recommend them.
• Sample part quality dramatically better than the production order. Classic bait-and-switch. Always specify in PO that production parts must match approved sample to within stated tolerances.

How to run a pilot order before scaling

1. 1

   Order 5-25 sample parts

   Enough to test multiple use cases and inspect dimensional consistency. Cost: usually $200–$1,000 depending on complexity.

2. 2

   Specify acceptance criteria explicitly in the PO

   “All parts must measure within ±0.05 mm of CAD nominal, surface finish ≤ Ra 1.6 µm on faces marked X, with full dimensional inspection report.”

3. 3

   Insist on First Article Inspection (FAI)

   A documented inspection of part #1 against every dimension on the drawing. Reveals systematic issues before the batch is finished.

4. 4

   Inspect on receipt

   Check 100% of pilot parts. Document non-conformances with photos. Use these in the next quote conversation.

5. 5

   If accepted, lock in commercial terms

   After successful pilot, scale to production with the volume discount, blanket order release schedule and longer payment terms.

6. 6

   If rejected, decide pivot or re-pilot

   Either give the supplier a corrective-action chance (with deadline) or switch suppliers. Don’t scale a supplier who failed the pilot.