Should I do during-production inspection (DPI)?

Question

Accepted Answer

Short Answer: Yes for New Suppliers and Custom Products - Catching a Fault at 15% Beats Finding It at 100%

Direct Answer

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

An inspector observing products on a running production line — DPI checks the process while faults are still cheap to correct.

When DPI Is Clearly Worth It

A supplier you have not used beforeYou have no production history to rely on, so verify the process rather than the outcome.

Anything custom or tooledA tooling fault repeats across every unit and is the single most expensive defect class.

A long production runThe longer the run, the more units are at risk before anyone looks.

A product with a critical safety featureErrors here are not commercially recoverable.

A repeat order from a stable supplierHere a final PSI alone is often proportionate.

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.

28%Inspections finding major defectsQIMA Q1 2026, China factories

~$198Typical DUPRO costRun at 15-30% completion

~$12,400Average cost of skipping DUPROOn custom tooling orders

10-15%Defect reductionFrom regular scheduled inspection

A technician adjusting an injection mould in a workshop — Tooling faults repeat across every unit, which is why timing matters.

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.

Consumer electronics35% first-pass failure

Children's toys31%

Silicone and plastics24%

Apparel22%

Furniture and home19%

Commodity and bulk11%

Timing the Visit

1

Target 15-30% completion

Early enough to correct, late enough that the process is genuinely running.

2

Confirm the real production start

Factories often report starting earlier than they did; verify before booking.

3

Send the checklist and golden sample in advance

The inspector needs the reference before they arrive, not after.

4

Ask for photographs of the line, not only the product

Process evidence is what makes DPI worth more than an early PSI.

5

Agree the corrective-action window in writing

A finding with no agreed response date is only an observation.

Two product units placed side by side for comparison on a bench — The inspector needs your approved reference before they arrive.

Case: A Tooling Fault Caught at 18%

Buyer: US kitchen-gadget brand, 12,000 units, custom mould

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.

OutcomeA $198 inspection prevented a full-run scrap the client's own estimate put near $26,000.

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 check

RND SOURCING — Yiwu, Zhejiang, China. Written by our sourcing desk from first-hand market work.