Key criteria
The right finishing subcontractor cuts scrap, lowers cost and keeps delivery on time. Check five things: a quality standard (ISO 9001), a test certificate on every lot, capacity that matches your volume, lot-to-lot consistency, and clear communication / language.
For exports, watch restricted substances too — zinc plating should be Cr3+ (Cr6-free) with RoHS/REACH documentation.
What foreign factories (Japanese/Chinese/Korean) should ask
Do they support your language (Japanese/Chinese/Korean/English) so specs are clear? Do they have experience with automotive/electronics maker standards? Can they hold a hardness (HRC) band and a salt-spray rating to your spec?
Ask about logistics too: do they pick up and deliver to your industrial estate, and on what cycle?
Red flags to avoid
No test certificates, no in-house lab, refusal to accept a sample, or dodging questions about Cr3+/RoHS.
Best practice: send a sample to be processed and tested first, and review the real report before committing to a large lot.
FAQ
How do I choose a plating subcontractor?+
ISO 9001, a certificate per lot, capacity for your volume, lot-to-lot consistency, and language plus export documentation (Cr3+/RoHS).
What languages can you handle for foreign factories?+
V.S. Heat Treatment supports Thai, English, Japanese, Chinese and Korean — so specs are communicated precisely.
Can I test before a full order?+
Yes — send a sample, we harden or plate it, run lab tests and return it with a report.
Free Engineering Tools
- Hardness Converter HRC ↔ HV ↔ HB
- Which Steel Grades Harden — and How Far
- Fastener Weight: pcs ↔ kg
- Finishing Specification Builder for Purchasing and QC
- Salt Spray Test Plan Builder
- Coating thickness → thread fit (GO/NO-GO)
- Hydrogen Embrittlement — is baking required?
- Bolt Tightening Torque & Proof Load
- Thread Engagement Length
- Bolt Size Estimator (from load)
- Bolt Property Class — Mechanical Properties (ISO 898-1)
What this article covers at our plant
Related comparison guides
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- Black oxide vs PhosphateBlack oxide vs phosphate: which finish for screws, nuts and bolts?
- Electroplated zinc vs Hot-dip galvanizingZinc plating vs hot-dip galvanizing: which one does your fastener need?
- Zinc plating vs Zinc-nickelZinc plating vs zinc-nickel: when is the upgrade worth paying for?
- Barrel plating vs Rack platingBarrel plating vs rack plating: how small fasteners are actually plated
- Zinc phosphate vs Manganese phosphateZinc phosphate vs manganese phosphate: match the coating to the job it does
Technical content review
Reviewed by the V.S. Heat Treatment QA and production team—heat-treatment and finishing operations since 1994 under an ISO 9001:2015 quality system.
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