During Production Inspection in China: How Ecommerce Brands Catch Defects Before Production Finishes (2026)

During production inspection in China—often called DUPRO or an in-process inspection—is a quality check performed after mass production has started but before the order is complete. The inspector checks real production output, materials, workmanship, process controls, quantities, and the factory's correction plan while there is still time to stop defects from spreading across the entire order.

This inspection is useful when the product is new, the production process is complex, an earlier order had defects, delivery timing is tight, or the buyer cannot afford to discover a systematic problem at final inspection. It does not replace a golden sample, first article inspection, or final random inspection. It connects those controls by showing whether the approved requirements are being followed during the actual production run.

What Is During Production Inspection?

During production inspection is an on-site or factory-side quality review conducted while a purchase order is being manufactured. It normally takes place when enough units are available to reveal the production process, but enough work remains for corrections to affect the unfinished balance. Many buyers plan it around 20% to 50% completion, but the correct timing depends on the product, process, lead time, defect risk, and correction window.

The objective is not merely to count defects. A useful DUPRO answers five operational questions:

• Is the factory producing the same product revision, materials, components, colors, labels, and packaging that the buyer approved?
• Are production methods and measurements stable across operators, lines, shifts, cavities, machines, or subcontracted processes?
• Are current defects isolated incidents or evidence of a systematic process problem?
• Can the factory contain affected units and correct unfinished production before the shipping date?
• Does the order remain likely to meet the required quantity, quality, packaging, and delivery plan?

A DUPRO report should therefore combine product inspection with process evidence. Photos of defective units are useful, but the report should also identify the affected production date, line, batch, machine, cavity, operator group, component lot, or subcontracted stage whenever practical.

DUPRO vs Other Quality Inspections

Each inspection stage answers a different question. Treating them as interchangeable creates gaps.

For many ecommerce brands, a practical sequence is: approve the product specification sheet, lock a golden sample, inspect the first production output, conduct DUPRO on higher-risk runs, and finish with an AQL-based final inspection.

When Ecommerce Brands Should Use DUPRO

Not every low-risk repeat order needs an in-process visit. DUPRO is most valuable when the cost of late discovery is higher than the inspection cost.

Strong use cases include:

• A first order from a new factory. The supplier's sales communication may be good, but production discipline is still unproven.
• A new product, material, mold, printing method, assembly process, or packaging design. Early approval does not guarantee stable mass production.
• A long production run. Defects can multiply across thousands of units before final inspection.
• Multiple lines, machines, cavities, shifts, or subcontractors. One approved sample may hide variation between production sources.
• A history of repeated defects. The inspection can verify whether the supplier's corrective action is actually working.
• Products with safety, regulatory, fit, dimensional, electronic, functional, cosmetic, or labeling risk. The check should focus on critical-to-quality characteristics, not a generic checklist.
• A fixed launch or stockout deadline. DUPRO can identify schedule slippage and rework risk before the planned final inspection.
• Expensive rework or destructive assembly. Problems are cheaper to correct before products are sealed, glued, welded, filled, sterilized, packed, or shipped.

DUPRO may be unnecessary for a small, stable repeat order from a proven supplier when materials, process, specifications, and defect history have not changed. In that case, final inspection and supplier performance monitoring may provide better value.

What a During-Production Inspection Should Check

The checklist must come from the purchase order, approved sample, drawings, bill of materials, packaging requirements, test methods, defect definitions, and relevant compliance documents. A generic checklist is not enough.

The inspector should use calibrated or verified measurement equipment where required and record the method, units, tolerance, sample size, and results. A photograph of a caliper without the specification limit or unit identity is weak evidence.

How to Plan a DUPRO Step by Step

1. Define why the inspection is needed

Identify the top risks: material substitution, color variation, dimensional drift, weak assembly, packaging damage, label error, process change, delivery delay, or recurrence of a known defect. This determines the timing and checklist.

2. Set a meaningful inspection window

Do not schedule only by a percentage written in a template. Confirm that critical operations are running, enough finished and in-process units exist, all relevant SKUs or variants are available, and several days remain for containment and correction.

3. Freeze the reference documents

Send the inspector the current purchase order, specifications, approved sample photos, drawings, tolerances, artwork, packaging rules, testing methods, defect classifications, and previous corrective actions. The purchase order quality terms should state inspection access, acceptance criteria, rework responsibility, and shipment-release conditions.

4. Confirm the real production location

Verify the legal supplier, factory address, line, subcontracted stages, and contact person. If printing, coating, electronics, packaging, or assembly happens elsewhere, decide whether those locations or incoming records also need review.

5. Build a risk-based checklist

Prioritize critical-to-quality characteristics and known failure modes. Specify exact test methods and pass criteria. Avoid instructions such as “check quality” or “make sure it is good.”

6. Inspect product and process

Select units from different times, lines, machines, cavities, cartons, workstations, or component lots where possible. Review incoming materials, in-process output, finished output, rejected units, rework areas, packing stations, and production records.

7. Hold a same-day factory review

Separate confirmed facts from assumptions. Agree which units must be quarantined, what production must stop, what can continue, who owns each corrective action, what evidence is required, and when verification will occur.

8. Verify corrections and remaining production

A report alone does not close the issue. Require evidence that affected units were identified, rework was completed, root cause was addressed, new output conforms, and the unfinished balance followed the corrected process. Final inspection should still verify the completed shipment using the agreed AQL inspection levels.

How to Sample Unfinished Production

An in-process inspection often cannot use a standard final-random-inspection plan across the entire order because much of the order does not yet exist. The inspector should record the available quantity and sample separately from unfinished production.

The sampling plan should cover variation sources that matter:

• Different SKUs, sizes, colors, and packaging configurations.
• Different production lines, machines, tools, mold cavities, or assembly cells.
• Different shifts, production dates, operators, and component lots.
• Units before and after a setup change, maintenance event, or corrective action.
• Finished units, in-process units, reworked units, and rejected units.

Do not present an early sample as proof that the whole purchase order passed. State clearly what existed, what was inspected, what had not yet been produced, and what follow-up is required. The final shipment decision should use the completed batch, contractual criteria, and appropriate sampling plan.

What to Do When Defects Are Found

The response should depend on defect severity, recurrence, affected scope, and whether the process can continue safely.

1. Contain the problem. Identify and segregate suspect finished goods, work in progress, components, and packaging. Stop the affected process when critical or systematic risk justifies it.
2. Define the defect precisely. Reference the specification, test method, tolerance, approved sample, photo, and affected unit IDs.
3. Map the affected scope. Trace production dates, lines, shifts, component lots, tools, cavities, and subcontractors.
4. Decide disposition. Rework, repair, sort, replace, downgrade, scrap, or accept only through an authorized written deviation.
5. Correct the process. Fix instructions, settings, fixtures, materials, training, maintenance, incoming checks, or error-proofing—not only the inspected pieces.
6. Verify effectiveness. Inspect new output after correction and confirm the defect rate and critical characteristics have improved.
7. Protect shipment release. Do not release the final balance payment or shipment only because the supplier promises to fix the issue. Require evidence and an independent re-inspection when risk warrants it.

For repeated or systematic problems, use a formal supplier corrective action request. The supplier should provide containment, root cause, permanent action, responsible person, due date, evidence, and effectiveness verification.

Common During-Production Inspection Mistakes

How SourceToDoor Supports In-Process Quality Control

SourceToDoor can coordinate during-production inspection as part of a wider China sourcing and fulfillment workflow:

• Verify the actual supplier, production factory, subcontractors, and production location.
• Convert product requirements, approved samples, and defect history into a practical inspection checklist.
• Coordinate inspection timing against real production progress instead of supplier estimates alone.
• Inspect materials, in-process work, finished units, labeling, packaging, quantity, and schedule risk.
• Escalate critical or systematic defects and track containment, rework, and corrective-action evidence.
• Coordinate follow-up inspection, final random inspection, China warehousing, shipment consolidation, and fulfillment preparation.
• Keep inspection records connected to repeat orders so recurring supplier problems become visible.

This creates a practical control loop: requirements define what should happen, in-process inspection shows what is happening, corrective action fixes deviations, and final inspection confirms the shipment before release. For the wider supplier-selection and production-control workflow, review the SourceToDoor Sourcing Wiki.

Frequently Asked Questions

What does DUPRO mean in quality inspection?

DUPRO means during production inspection. It is performed while a purchase order is being manufactured, after production has started and before it is complete, so defects and process problems can still be contained and corrected.

At what production percentage should DUPRO happen?

Many inspections are planned around 20% to 50% completion, but percentage alone is not enough. Schedule when critical operations and variants are running, representative output is available, and enough time remains for correction and verification.

Does during production inspection replace final inspection?

No. DUPRO evaluates available production and process control while the order is unfinished. Final inspection evaluates the completed, normally packed shipment against the agreed acceptance criteria before release.

How many units should be checked during production?

There is no single correct number. The plan depends on available quantity, order size, product risk, variants, defect history, process variation, contractual requirements, and the inspection objective. Record both the available quantity and the actual sample.

Can a DUPRO prevent delivery delays?

It cannot guarantee on-time delivery, but it can expose material shortages, low output, rework, bottlenecks, subcontracting problems, and quality failures earlier. The factory must then provide a realistic recovery plan that is monitored.

Who should choose the inspection samples?

The inspector should choose samples independently from relevant lines, shifts, machines, cavities, component lots, workstations, and finished or in-process quantities. Factory-selected samples increase staging risk.

What happens if critical defects are found?

Contain affected goods, stop the relevant process when appropriate, trace the affected scope, correct the cause, verify new output, and require follow-up inspection. Shipment and payment release should follow the purchase order and risk-based evidence, not an informal promise.

Is DUPRO worth the cost for a repeat order?

It is usually worthwhile when the supplier, material, process, tool, specification, line, subcontractor, volume, or defect risk changed—or when past problems repeated. Stable low-risk repeat orders may need only targeted process records and final inspection.