Why the factory's own QC isn't enough
A Chinese factory will tell you it has a QC department, and most do. The question is whose interest that department serves. The factory's inspectors are paid by the factory, report to the factory, and are measured on shipping orders on time. When a batch sits on the borderline, the pressure points in one direction. Independent quality control means someone who works for you, not the supplier, checks the goods against your written standard. That is the whole point: you are the importer of record, the goods are your liability the moment they land, and the only QC that protects you is QC you commission yourself.
It starts before production, not at the end
You cannot inspect against a standard that does not exist. Before a single unit is made, two documents do most of the work:
- A spec sheet that pins every measurable detail: dimensions with tolerances, materials and grades, colour as a Pantone or TPX code rather than "navy blue", weight, finish, packaging, labelling, and carton markings.
- A golden sample, also called a sealed or pre-production sample (PPS): one physical unit you and the factory both approve and sign, with a copy kept on each side. It becomes the reference every later inspection measures against.
Skip this and every later argument turns into your word against theirs. With it, "defective" has a definition an inspector can hold a unit up to. This is also why a bulk run so often drifts from the sample you approved, which is its own question worth reading.
The three checkpoints
Run inspections at three points in the build. Each one catches a different failure, at a stage where it is still cheap to fix:
- Incoming and first article (IQC / FAI). Before mass production, the factory makes a small first run on the real line. You confirm it matches the golden sample and spec. This is where a wrong material or a misread drawing surfaces while only a handful of units exist.
- During production (DUPRO). Once 20 to 40 percent of the order is built, an inspector visits the line. Defects that only appear at volume show up here, with enough order remaining to correct the process. DUPRO is the checkpoint importers skip and later regret.
- Pre-shipment inspection (PSI). When the order is 100 percent produced and at least 80 percent packed, an inspector pulls a random sample and checks workmanship, function, measurements, and packaging against your standard. This is the last look before the goods leave the country.
For a large first order you want all three. For a repeat order from a factory you trust, a DUPRO plus a PSI usually does it. The PSI is the one nobody should skip, and whether it earns its cost has a full answer of its own.
What AQL level should you use?
AQL, the Acceptable Quality Limit, is the sampling standard that decides how many units an inspector pulls from the order and how many defects the batch can contain before it fails. It is defined in ANSI/ASQ Z1.4, the same table published internationally as ISO 2859-1. Inspectors sort faults into three classes, critical, major, and minor, and you set a limit for each. A common consumer-goods setting is 0 / 2.5 / 4.0: zero critical defects allowed, up to 2.5 percent major, up to 4.0 percent minor, sampled at General Inspection Level II. Tighten the major limit for products where a fault is costly or unsafe. The value of AQL is that nobody opens all 5,000 units; a statistically chosen sample stands in for the whole batch on maths both sides agreed in advance.
The payment lever that makes QC count
An inspection report only has teeth if it can stop the money. Structure the purchase order so the balance falls due after a passed pre-shipment inspection, rather than on the ship date. The standard split is a 30 percent deposit and a 70 percent balance on a passed PSI. A factory that knows the balance depends on the report fixes the problems before shipping. A factory already paid in full has no reason to reopen a sealed carton. That one clause is what turns quality control from a piece of paper into the thing that actually protects your order, and it sits at the centre of safe payment terms with any Chinese supplier.
Who actually does the inspecting?
You have three options, in rising order of independence:
- The factory's own QC: free, and the weakest, for the reason at the top of this page.
- An independent inspection firm: SGS, QIMA, Bureau Veritas, Intertek, or TÜV Rheinland send a trained inspector to the registered site and report against your spec. Pricing runs roughly 250 to 350 US dollars per man-day. This is the standard for most orders.
- Your own eyes on the ground: a sourcing agent or staff member who knows the spec and sits in the factory's city. Fastest to react when something is off, and the closest thing to standing on the floor yourself.
Where Mila Sourcing fits
This is the three-stage QC we run on every order before goods ship and before your balance moves. A local, bilingual agent locks the spec and golden sample with the factory, runs the incoming, during-production, and pre-shipment checks against an agreed AQL, and films each one inside the same WhatsApp thread you are watching. You see the defects, the corrections, and the passed report in real time. That is the core of Sourcing Activation and Full Production Management.
Related, if you're tightening up quality right now: