How to vet a fastener supplier in China: 12 checks before the first order
Most bad fastener purchases are not caused by an outright dishonest supplier. They are caused by a supplier who was never asked the questions that would have revealed they could not do the job. This checklist is the one we would use ourselves.
A. Material and production
1. Ask which mill produced the steel, and require the melt route
Not the trading company, not the drawing plant — the mill. A supplier who can name the mill and produce a mill certificate with a matching heat number has a traceable supply chain. One who cannot, does not.
2. Confirm the heat-treatment arrangement
Class 8.8 and above requires controlled heat treatment. Ask whether it is in-house or subcontracted, whether furnaces are calibrated, and what records are kept per heat number. Property class is not a claim you can verify by looking at a bolt.
3. Ask what happens when the material is wrong
The answer tells you whether incoming material is actually inspected. A supplier with a spectrometry check and a rejection procedure will describe it specifically; one who does not will describe the parts arriving.
B. Coating and surface
4. Require a coating thickness figure in microns, not a coating name
"Galvanized" could mean 5 µm or 85 µm. State the minimum thickness, cite ISO 1461 where relevant, and require a coating thickness report with each batch.
5. For class 10.9 and 12.9, ask about de-embrittlement
Electroplating high-strength parts without a controlled bake risks delayed fracture. Ask when the bake happens relative to plating, and for how long. A supplier who has never been asked will hesitate — and that hesitation is the answer.
6. Check the passivation type on zinc plating
Trivalent passivation is the norm for REACH compliance. Hexavalent chromium should not appear in a modern supply chain at all.
C. Inspection and documentation
7. Ask for a sample inspection report before you order
Not a certificate template — an actual report from a real batch, showing measured values against tolerances. Reports with only "pass" ticks are not inspection reports.
8. Establish who pays for third-party inspection
SGS, BV or TUV inspection is a normal condition for a first order. A supplier who resists an inspection window is a supplier who expects the result to be inconvenient.
9. Confirm the failure procedure in writing
What happens if the pre-shipment report shows a non-conformance? The answer should be: the batch does not ship, a non-conformance report is issued, and rework or replacement is confirmed before re-inspection. Get it in writing before the first order, not during the first dispute.
10. Ask about change control
If the producing factory, material source or coating process changes between orders, are you told? Undisclosed supplier switching is one of the most common causes of unexplained quality drift in ongoing programmes.
D. Commercial and practical
11. Test the MOQ claim with a trial order
A supplier who says "flexible MOQ" and then quotes a container is not flexible. Place a genuine trial order, small enough to be cheap, and judge the whole process: response speed, packing quality, documentation completeness and whether the parts match the specification.
12. Assess who answers when something goes wrong
This is the decisive question. A trading intermediary who forwards your complaint to an unseen factory is not accountable. Ask directly: "if the shipment is non-conforming, who investigates and who pays?" The answer separates a supply partner from a middleman.
Red flags, in short
- "CE certificate" offered instantly for a product that is not in scope of a harmonised standard
- Mill certificate with no heat number, or a heat number that does not match the packing list
- Inspection report containing no measured values
- Price well below the market range for the stated grade — usually the grade is not the stated grade
- Reluctance to accept third-party inspection
- No answer to "which mill?", or an answer that changes between conversations
- Payment terms demanding full prepayment with no trading history
What a good first order looks like
- A written specification confirmed back to you, with any ambiguity flagged before quoting
- A trial or sample quantity, with a first-article or pre-shipment inspection report
- Mill certificate, dimensional report and coating report travelling with the goods
- Packing labelled by part number, quantity, heat number and coating
- 30% deposit and 70% against the bill of lading for a first order — not full prepayment
- A named person on the supplier side who owns your account and answers within 24 hours
If a supplier passes those six, the relationship is worth scaling. If any of them is resisted, the resistance is the information you needed.