When sourcing metal parts from China for the first time – or switching suppliers – the qualification process matters as much as the price. A factory that looks competitive on paper can cause expensive problems if you skip the verification steps.
Step 1: Confirm It Is a Factory, Not a Trader
The most fundamental distinction: are you dealing with a factory (direct manufacturer) or a trading company (middleman)? Trading companies add 10-30% cost and remove your visibility into actual production quality. How to verify: ask for photos of production equipment with a current date on a whiteboard. A business license listing “manufacturing” (Chinese: zhizao) confirms factory status; “trading” (maoy) means a middleman. A video call walkthrough of the shop floor is the most reliable verification for remote buyers.
Step 2: Request a Quality Documentation Sample
A factory with a proper QMS should provide without hesitation: a sample dimensional inspection report for a recently shipped part, a material certificate for a material they commonly use, and a completed Certificate of Conformance for a past shipment. If a supplier hesitates or sends templated documents that look freshly generated – treat it as a red flag.
Step 3: Run a Prototype Order First
Never place a production order with a new supplier before running a prototype or small batch. A capable supplier will always support this – they know it is the correct qualification sequence. A supplier who pushes back on samples and insists on production-level MOQ for first orders should raise concerns. For the prototype: measure every critical dimension, test fit with mating parts, and document your findings. This data becomes your production acceptance baseline.
Step 4: Evaluate Communication Quality During RFQ
Response time, technical competence, and language quality during the RFQ stage predict your experience during production. A supplier who responds within 24 hours with specific technical questions about your drawing is showing engineering competence. A supplier who ignores technical specifications and just sends a price is not reading your drawing carefully. At Conwhole Hardware, every RFQ gets a drawing review and DFM feedback before quoting – because an ambiguous spec at the quote stage becomes a non-conformance at delivery. Send us your drawings to experience this process.