I often hear purchasing managers complain that Vietnamese factories “look great on paper, but never deliver what was promised.” I’ve had the same experience. Some factories looked solid in their brochures, but during a visit, their machines or processes didn’t match the capabilities they claimed.
To find a reliable manufacturer for custom metal parts in Vietnam, you need a structured vetting process—from technical specifications to audits, from sample orders to long-term tracking. I’ll break it down below. 1
This guide will help you skip the painful trial-and-error phase and focus on real, verifiable capability.
What are the best methods to vet suppliers in Vietnam?
In my early sourcing work, the biggest mistake I made was assuming a supplier “understood what I wanted.” Once I began documenting specs clearly and evaluating each factory in a structured way, things changed.
The best vetting method is to evaluate factories across multiple dimensions—equipment, experience, certifications, communication, and trial results—not just based on paperwork. 2
Dive deeper
Here’s the structured vetting checklist I follow when evaluating a Vietnamese metal parts manufacturer:
| Evaluation Category | What to Check | Why It Matters |
|---|---|---|
| Equipment & Tech Capabilities | CNC machines, stamping presses, welding tools, finishing stations, CMMs | Equipment defines what tolerances and finishes they can truly achieve |
| Raw Material Traceability | Can they provide MTCs 3? Batch tracking? Non-destructive testing? | No matter how skilled, bad raw material = bad parts |
| Certifications | ISO 9001 4, IATF 16949 5, RoHS 6, export licenses | These indicate quality systems and export experience |
| Similar Part Experience | Ask for photos of parts with similar tolerances or finishes | A real sign of hands-on knowledge |
| Pilot Orders | Run a small batch to test dimensions, finish, packaging | It’s cheaper to discover issues at this stage |
| Factory Audits | Virtual or onsite audits 7—inspect machines, QC stations, floor workflow | What’s “claimed” vs. “real” often doesn’t match |
| Communication Skills | Quotation turnaround, understanding of drawings, ability to flag issues | Clear answers = less risk down the line |
Should you work with sourcing agents in Vietnam?
Early on, I avoided sourcing agents because I thought they were just middlemen adding costs. But I’ve learned that in many cases, a good agent can save far more than they cost—if chosen wisely.
Yes, it’s worth working with sourcing agents in Vietnam 8 if they bring strong factory networks, technical vetting ability, and local management. But pick them wisely and define roles clearly.
Dive deeper
Here’s a balanced breakdown of the pros and cons of working with sourcing agents in Vietnam:
| Pros | Cons |
|---|---|
| Shorten supplier search with pre-vetted networks | Adds cost (service fee or commission) |
| Local presence allows in-person audits and live production tracking | May reduce transparency—communication may get filtered |
| Familiar with local business culture, compliance, labor laws | Some agents push “convenient” suppliers instead of the best fit |
| Help with logistics, customs, QC coordination, language barriers | Not all agents are technically trained—they might not understand your specs fully |
Use a sourcing agent when:
- You’re handling complex, multi-part projects
- You can’t visit factories yourself
- Quality standards are strict (automotive, aerospace, etc.)
- You plan to build a long-term supply chain in Vietnam
Go direct when:
- Parts are simple and easy to describe
- You have previous experience in Vietnam
- Quantities are low (sample batches)
- Cost control is a top concern
How do you validate a manufacturer’s capabilities?
In the early days, I was impressed by brochures and fast emails. But what really matters is whether they can make your parts—consistently and accurately. Capability isn’t claimed, it’s proven.
Validate a manufacturer’s ability by testing—not asking. Specs, samples, process flows, and first-article inspections 9 give you the real answers.
Dive deeper
Here’s the full validation framework I use:
1. Technical Specification Review
Send your full drawings and spec sheets. Ask how they would machine or assemble your part. Request process flowcharts, quality plans, and inspection reports.
2. Machine and Facility Check
Either visit in person or ask for a live video tour. See if they have relevant equipment (e.g., CNC for your required tolerance) and whether it’s operational—not sitting idle.
3. Pilot Run / First Article
Ask for a small batch based on your full drawing. Check all critical dimensions. Run corrosion or fatigue tests if needed. Use third-party inspectors 10 for an unbiased report.
4. QC System
Review their inspection steps: incoming material check, in-process control, and final inspection. Ask how they handle rework and what their internal defect rate is.
5. Audit Their Certifications
Confirm ISO and other certificates are real and not expired. Ask if they’ve been audited by third parties (like SGS or BV). Check if they’ve exported to your market before.
6. On-Time Delivery & Logistics
Ask for past lead time records. Do they send production progress updates? Do they have logistics partnerships for DDP or DDU shipping?
7. Packaging & Export Readiness
Is the packaging export-compliant (e.g., IPPC pallets 11, rust prevention)? Can they generate proper commercial invoices, packing lists, and certificates of origin?
What red flags should you avoid when choosing a factory?
I’ve seen many buyers ignore early warning signs—then regret it when parts fail inspections or shipments get delayed. It’s easier to avoid the wrong factory than to fix the mess later.
There are clear red flags when choosing a factory. If you see these, it’s best to pause—or walk away.
Dive deeper
Here are common red flags and why you should act on them:
| Red Flag | What It Means | What To Do |
|---|---|---|
| Generic responses, vague answers, stock photos | They might be a trading company, not a factory | Ask for real, timestamped factory photos or videos |
| No export experience | May not understand compliance, shipping documents, customs codes | Ask who their current export clients are and if they can ship under your Incoterms 12 |
| Slow or unclear communication | Often leads to delays, misunderstandings, or poor execution | Test them with technical questions early on |
| Old machines, broken equipment, messy floor | Indicates low precision and poor maintenance | Request video of operations; check calibration certificates |
| No internal QC team | Likely to deliver inconsistent or out-of-spec parts | Ask for an organizational chart and QC protocols |
| Very high MOQs but no relevant project experience | They may want your business but aren’t equipped to deliver | Always test with a small trial run first |
| Too-good-to-be-true price or unrealistic delivery times | They’re probably cutting corners or will later renegotiate | Ask for detailed cost breakdown and penalty clauses |
Conclusion
If you follow this process—from defining specs to vetting, from testing parts to ongoing QC—you’ll avoid 80% of sourcing problems and find real, capable partners in Vietnam.
Footnotes
1. Guide to reliable supplier sourcing in Vietnam. ↩︎
2. Why multi-dimensional supplier vetting reduces sourcing risks. ↩︎
3. Explanation of Mill Test Certificates (MTCs) in manufacturing. ↩︎
4. ISO 9001 quality management certification details. ↩︎
5. IATF 16949 standard for automotive manufacturing. ↩︎
6. EU RoHS directive for restricted hazardous substances. ↩︎
7. Supplier audit services overview by SGS. ↩︎
8. Overview of sourcing agents in Vietnam. ↩︎
9. First Article Inspection (FAI) explained by ASQ. ↩︎
10. Bureau Veritas inspection services for manufacturers. ↩︎
11. IPPC wood packaging standards for international shipping. ↩︎
12. ICC guide to international trade Incoterms. ↩︎
