During Production Inspection: Catch a Bad Batch Early
A during production inspection catches a repeating defect while the factory can still fix it cheaply. By the time the goods reach the port the same defect is yours, and every option left costs money.
| Where You Catch It | What It Costs You |
|---|---|
| During production | A fix, a few days |
| Before shipment | Rework, delayed sailing |
| At your warehouse | Rework, duty, storage |
| At the customer | Returns, bad reviews, replacements |
The same defect gets more expensive at every step it travels from the factory floor.
What a During Production Inspection Is
A During Production Inspection (DUPRO) is an independent visit to the factory while your order is still being built. The inspector pulls finished units off the line, checks them against your approved sample and specs, and reports what has slipped early enough to stop it spreading through the rest of the order.
The right moment is not a fixed percentage. Inspection companies book it anywhere from 20% to 80% complete, but what matters is that enough units are finished to sample and enough are still unbuilt for a fix to reach them.
Not every order earns one. How much checking a batch deserves comes down to what can go wrong in it, and that judgment is the core quality control in China decision.
The Water Bottle Case: Same Defect, Two Outcomes
One repeating defect can ruin an order or cost almost nothing, and the only variable is when somebody looks. Take a worked example: an importer orders 3,000 water bottles and plans to inspect only before shipment. By then every lid carries the same undersized seal, invisible from the outside, and the choices are rework 3,000 units, discount the lot, or reject it.
Run the same order with a visit at 20% complete and the story turns around. About 600 units are done when the inspector finds the seal. Production stops, the supplier corrects the spec, the remaining 2,400 are built right, and the delay is roughly 5 days.
What the Inspector Looks At
A good visit tests whether the order is on track to be right, not just whether today’s units pass. The inspector works to a written standard, which is why an approved sample and an inspection checklist do more for the result than the inspector’s own judgment.
Setup: the approved materials and components are the ones actually in use.
Workmanship: finished units match the sample, and a flaw is either a one-off or repeating.
Function and measurement: the product works, and dimensions and weight are in range.
Packaging and labels: barcodes, language, and carton marks, before the whole order is packed.
A flaw shared by several units is a signal about the process, not bad luck. A sample shows the trend rather than the state of every carton, and the trend is enough to act on while whatever caused it is still running.
What to Do With the Report
A report changes nothing until it becomes an instruction the factory has to answer. Three moves turn a finding into a fix, and all three are easier while the line still moves.
Count what is already built. That tells you how big the problem is, not what to do about it.
Let the severity pick the option. A cosmetic fault can be reworked, held, or taken at a discount, while a safety, legal, or function fault leaves only rework or rejection, whatever the quantity.
Get the fix in writing, then re-check. What changed and who verified it, followed by a short second visit on corrected units before the balance goes out.
When the Check Earns Its Keep
Five situations pay for the visit on their own. What decides it is the risk in this batch, not how many orders you have placed.
A new supplier: a 50-unit sample says nothing about how a factory performs at 2,000.
A complex product: more parts and more steps mean more places for one error to repeat.
A long run: if the order takes 3 weeks, a visit in week 2 still leaves room to act.
A change: new material, new subcontractor, moved line, or a promised fix the factory has not proved.
A large order: a small defect rate across 10,000 units is still hundreds of bad pieces.
One inspector day sits far below the cost of reworking a finished batch. The practical question is which of the inspection companies in China can get someone there on the day your output reaches a useful level.
Where It Sits Between the Other Two Checks
Buyers see three stages on an inspection quote, and each buys a different kind of room to act. Which of the three you book follows the product and the batch: a simple mature item may need only the last, while a changed material, process, or subcontractor can justify all three on a repeat order.
| Stage | When It Happens | What You Can Still Change |
|---|---|---|
| Initial production check | Start of production | Materials and line setup |
| During production inspection | Order partly built | Most of the batch |
| Pre-shipment inspection | Production done, mostly packed | Little, rework is costly |
An initial production check looks at materials, components, and setup. The during production visit looks at what the line is turning out, and a pre-shipment inspection confirms whether the finished batch is fit to pay for. None of the three replaces another.
Production monitoring is a different service. It keeps someone in the factory continuously with repeated reports, which suits a high-risk line rather than a normal order.
What It Cannot Do
The visit checks a sample, not every unit. Sample size follows AQL sampling, so a clean result is strong evidence rather than a promise about every piece in the carton.
It does not certify compliance. An inspector can confirm the specified materials, markings, and workmanship are the ones you approved, but a formal safety judgment needs laboratory testing.
And it cannot fix a factory that will not cooperate. A supplier that turns defensive or stalls access is telling you something worth knowing, and a supplier quality audit tests whether the controls exist at all.
FAQ
Q1: Can the factory not just check its own production?
It should, and its team still answers to the factory, not to you. An outside inspector gives you evidence you can use when the factory says the batch is fine and your customer says otherwise.
Q2: Who arranges the visit, me or the factory?
You book and pay for it, and the factory grants access. Write that access into the purchase order, so a check at agreed stages is a term of the deal rather than a favor.
Q3: The factory subcontracts part of the work. Does the visit cover that workshop?
Only if you say so up front, since an inspector sent to the main plant will not travel to a plating shop down the road. Ask which processes leave the building before you book.
Q4: Can I arrange this without flying to China?
Yes, and most buyers do. A local inspection company visits and sends the report and photographs wherever you are, which is how a small importer holds a standard remotely.
Q5: Does the inspection slow my production down?
A routine visit does not stop the line, since the inspector samples finished units while production continues. It only causes a halt when there is a problem worth halting for.
Q6: How fast do I need the report back?
Same day or next day, which matters more here than at any other stage. A report three days late describes a batch that has already moved on.
Q7: The inspector finds a repeating defect partway through. Stop the line or let it finish?
Stop by default, since a wrong part keeps flowing into everything built after it just as a wrong process does. Let the line run only where the faulty step can be isolated and the fix is already verified, never where safety or function is involved.
Q8: I have several orders running at once. Can one visit cover more than one factory?
No, each factory needs its own visit, though an inspection company can schedule them in the same week to cut travel cost. One report format across suppliers is what makes the results comparable.
Conclusion
The value of going early is not the defect you find, it is how much of the order is still unmade when you find it. In the worked example the order failed on timing, not on anything the factory could not build correctly.
The hard part is booking each visit at the right moment and chasing the fix afterward, which is what manufacturing control support handles.
