Why does every Chinese factory say yes?
Send the same drawing to ten Chinese suppliers and count the yeses. You will usually get ten, and several of those companies have never made anything like your product. The salesperson answering is paid on closed orders, and in Chinese business culture a flat no is impolite, so a fast yes often signals interest in your order, whatever their line can do. A trading company says yes and then goes looking for a factory. A factory with the wrong equipment says yes and plans to subcontract the part it cannot make.
The wrong yes is expensive. It shows up weeks later as a sample that misses your spec, or as a production batch quietly farmed out to a workshop nobody audited. So stop asking suppliers whether they can make your product; that question always returns yes. Check what their line makes today instead.
What does the factory already make today?
The strongest proof of capability is a close sibling of your product already in production. Ask which of their current products is nearest to yours in process and material, and ask for photos or video of it coming off the line. A factory proud of a product close to yours will show it without hesitation. Vague talk about a big catalogue, with nothing specific on the table, means the sibling does not exist.
Then spend a little money before you spend a lot: order a sample of that existing product. A stock sample costs $20 to $150 plus courier and shows you their real output quality with zero custom work involved. While it ships, check the paper. The registered business scope (经营范围) on the license should name your process family, such as plastic products manufacturing, metal fabrication or electronic assembly, and it should match the record on China's official registry at gsxt.gov.cn. A supplier whose scope reads wholesale and import-export is a trader, whatever the website says. That check has its own page: how to tell a real factory from a trading company.
Do their machines match your product?
Every product implies a process list, so write yours down before you talk to anyone. A plastic housing means injection moulding with enough clamping force for the part; if your part needs a 600 tonne press and their biggest machine is 250, no amount of goodwill closes that gap. A stainless bottle needs deep drawing, welding and polishing. An electronic device adds an SMT line for the boards and test rigs at the end of assembly.
Then ask for the machine list. Real factories keep one and share it without drama: machine types, tonnage, counts, sometimes photos. Match it to your process list and ask directly about the steps that are missing. Anodising, plating and silk-screen printing are often outsourced even by good factories. You want to know which steps leave the building, because subcontracted steps are where quality drifts first and where your audit never went.
Close the loop with a live video walk of the exact stations on your list. Ask them to walk from the gate to the machine that would run your part and show it running. A capable factory does this on a normal Tuesday; a trader stalls, sends a pre-recorded clip, or shows a partner site.
What questions do they ask you back?
A factory that can make your product reads the drawing and comes back with questions. Which grade of ABS, virgin or regrind. Whether the ±0.05 mm tolerance on one bore is real or a CAD default that would double the reject rate. Engineers call this DFM feedback (design for manufacturability), and it is the cheapest capability test you will ever run, because it happens in week one, before any money moves.
Silence is the warning. A supplier who takes a complex spec and answers only with a price and a lead time has not read it. Plant one deliberate tripwire: a single tight tolerance or a named material certificate buried in the spec. If nobody asks about it, you have your answer.
Is the sample made on the real line?
The paid sample is the exam. Ask for a pre-production sample made with the materials and processes that will run your order, and put it in writing: a sample off their line, on their tooling where tooling exists. A hand-finished unit from the sales office tells you nothing about the line.
Judge the process as much as the part: whether the first sample hit the spec you sent, and what happened when something missed. A factory that explains a miss and fixes it in one round is showing you how production will go. One that argues with your own drawing is also showing you how production will go.
When you approve a unit, sign and date two copies and seal them; that is your golden sample, the reference every later inspection compares against. Keep one caution in mind: the sample is the factory's best work, while the run is its average work. For a tooled or complex product, a pilot run of 100 to 500 units before the full order tells you whether the average holds. The gap between sample and run has its own page: why the production run comes out different from the sample.
When should you pay for a capability audit?
When the first order is worth serious money, put a third party on the floor before the deposit moves. A standard factory audit from SGS, QIMA, Bureau Veritas, Intertek or TÜV Rheinland costs roughly $300 to $600 for one auditor day and records what is physically there: the machine inventory against your process list, real production capacity, workforce, the QC lab and its records, and whether the name on the gate matches the license you verified. When capability is the question, ask for the manufacturing or technical audit rather than the basic supplier check.
Treat one certificate with suspicion: ISO 9001. It certifies a quality management system, a trading company can legally hold one, and borrowed or forged copies circulate. An audit report that names the site and lists the machines is worth a wall of framed certificates.
Where Mila Sourcing fits
This page is the checklist we run before an importer wires a deposit. Every supplier match in Sourcing Activation starts with the license and registry check, then a GPS-stamped video audit of the specific line that would run your product. A sample plan with a sealed golden sample follows before production money moves, and on Full Production Management orders we stay on the floor through tooling, pilot run and pre-shipment QC, inside a WhatsApp thread you watch in real time.
Related, if you are vetting a factory right now: