Should I do during-production inspection (DPI)?
Short Answer: Yes for New Suppliers and Custom Products - Catching a Fault at 15% Beats Finding It at 100%
A during-production inspection runs when roughly 15-30% of the order is complete. Its entire value is timing: a wrong material, a tooling error or a specification misread costs almost nothing to correct at that point, and can mean scrapping the whole run if it surfaces at pre-shipment instead.
What DPI Catches That PSI Cannot
A pre-shipment inspection tells you whether finished goods are acceptable. A during-production inspection tells you whether the process is going to produce acceptable goods, which is a different and much cheaper question to answer.
| Fault type | Caught at DPI | Caught at PSI |
|---|---|---|
| Wrong material grade | Change the material, minimal loss | Scrap the entire run |
| Tooling or mould error | Correct the tool before volume | Every unit carries the defect |
| Specification misread | Clarify and restart cheaply | Rework or reject |
| Colour or finish drift | Adjust the process | Sort and rework by hand |
| Assembly sequence fault | Retrain the line | Disassemble and rebuild |
When DPI Is Clearly Worth It
The Numbers Behind the Recommendation
This is not a theoretical preference. Inspection data across China factory visits in 2026 shows how often production diverges from the approved sample, and category-level first-pass failure rates make the risk concrete.
First-Pass Failure Rates by Category
Where your product sits in this table should shape how strongly you weight a during-production check. The high-failure categories are high-failure for structural reasons, not because of dishonest suppliers.
Timing the Visit
Target 15-30% completion
Early enough to correct, late enough that the process is genuinely running.
Confirm the real production start
Factories often report starting earlier than they did; verify before booking.
Send the checklist and golden sample in advance
The inspector needs the reference before they arrive, not after.
Ask for photographs of the line, not only the product
Process evidence is what makes DPI worth more than an early PSI.
Agree the corrective-action window in writing
A finding with no agreed response date is only an observation.
Case: A Tooling Fault Caught at 18%
The DPI at roughly 18% completion found consistent mould flash along one seam on every unit sampled - a tooling defect, not a workmanship issue. The factory reworked the mould over four days and reran the affected units. At PSI the same fault would have meant 12,000 defective pieces with no cheap remedy.
How RND SOURCING Schedules DPI
We push for a during-production check on every first order with a new supplier and on anything involving custom tooling, because that is where the money is. Our desk confirms the true production start with the factory rather than accepting the reported date, so the inspection lands in the right window. Findings come back to the client with photographs and an agreed corrective-action deadline before production continues. For orders where an independent inspector is warranted we book one; we are not an accredited inspection body ourselves.
Schedule a during-production checkRelated Questions
- What does a PSI checklist include?
- How much does a third-party inspection in China cost?
- What is a 'golden sample' and why send it to the inspector?
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