In global manufacturing, the most expensive defect is the one found too late. A defect found on the production line costs pennies to fix; finding the same defect in your warehouse can cost your entire margin in returns and reputation damage.
During Production Inspection (DPI), also known as DUPRO, is your “early warning system.” Unlike a Pre-Shipment Inspection (PSI), which is a final pass/fail exam, DPI allows you to intervene while the factory is still running. It answers the critical question: “Is the factory building my product correctly, or are they making 5,000 units of trash?”
This guide provides a definitive operational framework for conducting DPIs, from timing your visit to a printable checklist for your inspector.
What Is During Production Inspection (DPI / DUPRO Inspection)?
During Production Inspection (DPI) is an on-site quality control check performed when 20–50% of the order is completed.
Where DPI Sits in the Timeline
- IPC (Initial Production Check): Checks the first 1–5% to verify materials and setup.
- DPI (During Production): Checks the first 20–50% to verify consistency and average quality.
- PSI (Pre-Shipment): Checks the final 100% produced / 80% packed lot for acceptance.
Why It’s Different from Pre-Shipment Inspection
PSI is a “gatekeeper” (stop bad goods). DPI is a “corrector” (fix the process). If a PSI fails, you have a disaster (shipment delay, rework costs). If a DPI fails, you have time to fix the remaining 50–80% of production.
What DPI Can and Cannot Guarantee
| DPI Can… | DPI Cannot… |
|---|---|
| Catch systemic defects (e.g., wrong logo color on all units). | Guarantee the final 50% will be perfect (factory might change workers). |
| Force the factory to adjust the machine/process immediately. | Verify final packaging (since most goods aren’t packed yet). |
| Verify the production schedule (are they really on time?). | Check total quantity (since production is unfinished). |
When Should DPI Be Conducted? (Timing + Readiness)
Timing is everything. If you go too early, you see “Golden Samples.” If you go too late, it’s just a Pre-Shipment Inspection.
- Ideal Timing: When 20–50% of goods are finished.
- Readiness Criteria:
- Mass production line is fully running (not just a pilot run).
- Raw materials for the full order are in the warehouse.
- Packaging materials are at least partially available.
Inspection Timeline Comparison
| Inspection Type | Timing | Purpose | Outcome |
|---|---|---|---|
| Initial Production Check (IPC) | 1–5% produced | Verify materials & setup. | Approve start of mass production. |
| DPI / DUPRO | 20–50% produced | Catch ongoing defects & check schedule. | Corrective Action Plan (CAP). |
| Pre-Shipment Inspection (PSI) | 100% produced / 80% packed | Final acceptance. | Pass/Fail for shipment release. |
| Container Loading (CLS) | Loading day | Verify qty & carton condition. | Seal number verification. |
Objectives of DPI (Why Brands Use Production Inspections)
- Early Detection: Finding a wrong color code on unit #500 saves you from re-making unit #5,000.
- Align Factory Output: Factories often “drift” from the Golden Sample after the first few days. DPI pulls them back to the spec.
- Reduce Rework: Fixing a glued part before the glue sets is easy. Fixing it after it’s packed in a retail box is expensive.
- Schedule Verification: Factories lie about progress. A DPI inspector counts the actual pile on the floor to tell you the real finish date.
DPI Inspection Process (Step-by-Step)
1. Planning & Scope
- Send the Golden Sample to the factory (if not already there).
- Define the AQL (Acceptable Quality Limit). Usually Level II, Major 2.5 / Minor 4.0.
2. Document Review
The inspector reviews your PO, Spec Sheet, and Packaging Artwork on-site.
3. Production Status Check
- Count semi-finished goods.
- Count finished goods.
- Check daily output rate to forecast completion date.
4. Sampling
Since goods aren’t packed, the inspector pulls samples from:
- The end of the assembly line.
- The “finished goods” pile.
- The “semi-finished” baskets (to check internal components).
5. On-Site Checks
- Visual: Workmanship check (scratches, stains, assembly gaps).
- Dimensional: Measure size/weight against the spec.
- Functional: Turn it on, pull it, twist it.
6. Reporting & Corrective Actions
The inspector shows the defects to the Factory Manager immediately. They agree on a plan: “We will adjust the machine pressure to stop the cracking.”
What Does DPI Check For? (Complete Checklist)
1. Production Organization
- Are work instructions visible at each station?
- Is there a dedicated “Rework Area”? (Or are bad units mixed with good ones?)
- Are raw materials stored off the floor?
2. Materials & Components
- Do incoming components match the BOM (Bill of Materials)?
- Check for unauthorized substitutions (e.g., cheaper plastic).
3. Workmanship (Visual)
- Appearance: Color, finish, cleanliness.
- Assembly: Gaps, alignment, glue residue.
- Defects: Scratches, dents, flash (excess plastic).
4. Measurements
- Product Dimensions vs. Tolerance (+/-).
- Product Weight.
5. Functionality
- Full function test (On/Off, modes).
- Abuse test (drop test, pull test).
6. Packaging & Labeling (If Available)
- Barcode scan check.
- Label placement and spelling.
Defect Classification & Acceptance Rules (Practical)
DPI is rarely a hard “Fail” like PSI. It’s usually “Pass,” “Pending,” or “Hold.”
- Critical (Safety/Regulatory): Sharp edge, mold, wrong compliance mark. -> STOP PRODUCTION.
- Major (Functional/Visual): Crack, wrong color, doesn’t turn on. -> HOLD & REWORK.
- Minor (Cosmetic): Small scratch, untrimmed thread. -> IMPROVE PROCESS.
“Pass with Corrective Actions”: The most common DPI result. It means “Keep producing, but fix X, Y, and Z immediately.”
DPI Report: What It Should Include
A professional DPI report is not just a checklist; it’s a status update.
- Production Status: “25% Finished, 40% Semi-Finished. Estimated delay: 3 days.”
- Defect List: “Found 5 units with cracked casing (Major). Factory adjusted clamp pressure to fix.”
- Photos: High-res photos of defects, production line, and warehouse storage.
- Measurement Table: Actual vs. Spec.
- Inspector’s Opinion: “Factory is messy and disorganized” or “Process is controlled.”
How to Prepare for a Successful DPI
Buyer Preparation
- Golden Sample: Essential. The inspector needs a physical reference.
- Defect Catalog: A PDF showing “This scratch is OK” vs. “This scratch is a Defect.”
- Authority: Tell the factory, “The inspector has the right to pull samples from ANYWHERE on the line.”
Factory Preparation
- Transparency: Don’t hide the “bad pile.”
- Staff: Have QC staff available to discuss findings.
- Access: Allow the inspector to see raw materials storage.
Common Findings & How to Fix Them Fast
| Finding | Immediate Action (Containment) | Long-Term Action (Prevention) |
|---|---|---|
| Color Mismatch | Sort all finished units. Remove bad ones. | Check masterbatch mixing ratio. |
| Measurement Drift | Stop the machine. Re-calibrate. | Update tooling maintenance schedule. |
| Dirty/Stained | Add cleaning station at end of line. | Workers must wear gloves/finger cots. |
| Wrong Label | Reprint labels. Rework packed units. | Update “Approved Sample” at packaging station. |
DPI vs PSI: Which One Do You Need?
- High Risk (New Supplier / Complex Product): Do DPI + PSI. (DPI to fix process, PSI to verify result).
- Medium Risk (Stable Supplier): PSI only.
- Time Critical (Cannot afford delay): DPI only. (Fix issues early so PSI doesn’t fail 1 day before shipping).
How to Choose an Inspection Service
- Inspector Competence: Do they know your product category? (Don’t send a textile inspector to check electronics).
- Reporting Speed: You need the report same-day to make decisions while the line is running.
- Local Coverage: Do they have inspectors near the factory to minimize travel costs?
- Escalation: Can you talk to a technical manager if the report is unclear?
FAQ
What is DPI in manufacturing?
A quality inspection performed when 20-50% of the production is complete, focusing on catching defects early in the process.
What’s the difference between DPI and pre-shipment inspection?
DPI happens during production to fix the process. PSI happens after production to accept/reject the shipment.
When should DPI be scheduled?
Ideally when 20-50% of the goods are produced.
What is included in a DPI checklist?
Production status, raw materials check, visual inspection, dimensional check, and functional testing.
What if defects are found?
You issue a Corrective Action Request (CAR). The factory must fix the process for the remaining production and rework the defective units already made.
Can DPI replace PSI?
Generally no. DPI doesn’t verify the final order quantity or packaging. However, for trusted suppliers, some brands skip PSI if DPI is perfect.
Printable During Production Inspection Checklist (Short Version)
- Schedule: Is production on track to meet ship date?
- Materials: Are correct raw materials being used?
- Process: Is there a “Golden Sample” visible to workers?
- Visual: Inspect 30-50 random units. Defect rate acceptable?
- Dims: Measure 5 units. Within tolerance?
- Function: Test 5 units. All pass?
- Action: Did factory agree to fix identified issues?