Quality does not always stay consistent throughout a production run. A factory may start with good workmanship and then cut corners as deadlines approach. A component supplier might deliver a second batch of substandard parts halfway through production. Workers may get faster but sloppier as they become more comfortable with the process. A During Production Inspection (DUPRO) is designed to catch these mid-production issues before they affect the entire order.

What Is During Production Inspection?

DUPRO — also called In-Process Inspection or Mid-Production Check — is an on-site quality inspection performed while production is underway, typically when 20 to 80 percent of the order has been completed. The inspector examines finished and semi-finished products, observes the production process, and assesses whether quality remains consistent with your specifications and the approved sample.

Unlike a pre-shipment inspection that gives you a snapshot of finished quality, a DUPRO gives you a window into the production process itself. It can identify quality trends that are developing, process issues that are causing defects, and progress problems that threaten your delivery date.

What Does a DUPRO Cover?

A during production inspection typically includes:

• Finished product inspection: Drawing samples from completed units and checking workmanship, function, and dimensions against your specifications
• Semi-finished product evaluation: Inspecting products at various stages of assembly to identify at which point defects are being introduced
• Production process observation: Watching the production line in action to spot bad practices, poor workstation setup, or process control gaps
• Production progress assessment: Counting completed units and comparing against the production schedule to determine whether the order is on track
• In-line testing verification: Checking that the factory's own in-line testing procedures are being followed correctly and consistently
• Raw material check: Verifying that materials being used in current production still match the approved specification (substitutions sometimes happen between batches)
• Packaging evaluation: If packaging has started, verifying that packaging materials and methods are correct

The key advantage of DUPRO is that you get information while there is still time to act. If a defect is identified, the factory can correct the process for the remaining units rather than having to rework the entire order.

When DUPRO Adds the Most Value

DUPRO is not necessary for every order, but it is particularly valuable in these situations:

• Large production runs: For orders with tens of thousands of units, catching a problem at 30% completion means 70% of the order can be saved.
• Continuous or long production runs: Products that are produced over many weeks are more likely to experience quality drift.
• Products with many hand-assembly steps: Handwork is more prone to inconsistency than automated processes.
• Factories with inconsistent quality records: If a supplier has had quality issues in the past, DUPRO helps you catch problems early.
• Time-sensitive orders: When you cannot afford post-production rework delays, identifying and fixing issues during production is critical.
• Orders with multiple components or sub-assemblies: Problems in sub-assemblies can be hard to detect in finished products but easy to see during production.

Common Pitfall: Only Checking Finished Units

A common mistake is treating a DUPRO like an early pre-shipment inspection — only checking finished products and not observing the production process. This misses the whole point of DUPRO.

The real value of a during production inspection is understanding why defects are happening and whether the process is set up to produce good quality consistently. If you only check finished units, you know there are defects but you may not know where in the process they originate or how to fix them.

Best practice: Ensure your DUPRO includes process observation, not just finished product checking. The inspector should walk the production line, observe in-line testing, and identify the specific process step where each defect type is introduced. This diagnostic information is what allows you and the factory to implement corrective actions that prevent the remaining units from having the same problems.

DUPRO vs. IPC vs. PSI: What's the Difference?

It can be helpful to think of these three inspection types as a timeline:

• IPC (Initial Production Check): 5-20% complete — verifies that production started correctly, with the right materials and setup
• DUPRO (During Production Inspection): 20-80% complete — checks that quality is holding and production is on track; identifies process issues mid-run
• PSI (Pre-Shipment Inspection): 100% complete, 80% packed — final quality verification before shipment

Many buyers use all three for critical orders: IPC to validate the start, DUPRO to monitor the middle, and PSI for final sign-off. For less critical orders, one or two of these may suffice.

Production Monitoring vs. DUPRO

DUPRO is a one-time snapshot of the production process. For very high-value or high-risk orders, some buyers opt for production monitoring — having an inspector on-site every day, or several days a week, throughout the production run.

Production monitoring provides much more comprehensive oversight but is significantly more expensive. It is typically used for:

• Very large or high-value orders where the cost of quality failure is extreme
• New factories where the buyer has no established trust
• Products with complex assembly processes and high defect risk
• Situations where the buyer has reason to suspect the factory may cut corners

For most orders, a well-executed DUPRO provides excellent value at a fraction of the cost of full production monitoring.

Conclusion

During production inspection fills the gap between initial production checks and final pre-shipment inspection. It is the only inspection type that gives you visibility into the production process mid-run and allows you to correct issues before they affect the entire order.

If you have a large order, a tight deadline, or a factory with inconsistent quality, adding a DUPRO to your quality plan can prevent costly surprises. Contact QCANT at cs@QCANT.com to discuss how during production inspection can fit into your quality control strategy.