Pre-dispatch inspection (PDI) is the final inspection of finished goods before they are released for dispatch. Its purpose is to confirm that the shipment matches the order and the agreed requirements: the right parts, in the right quantity, made to the current drawing, identified and packed correctly, with the documents the customer expects.
The basic idea is simple. The details are where PDI either protects the customer or becomes a formality. This article covers what PDI checks, how sampling works, how it differs from stage inspection, how to record it and the mistakes that weaken it.
What PDI is for
- Protecting the customer from receiving nonconforming, damaged, mislabelled or incomplete goods.
- Confirming dispatch readiness: that everything required for this shipment is complete, not just the parts.
- Creating a record of what was shipped and its condition, which matters if questions come up later.
- Giving one last view of the order as a whole, since PDI is often the only time all of it is in one place.
Note what is not on that list: finding the cause of defects. PDI sees the finished result, not how it was made. That job belongs to the inspection that happens during production.
What a PDI usually checks
The exact checklist depends on the part and the customer, but most PDIs cover the same areas:
| Check | What it confirms | How it is usually done |
|---|---|---|
| Identity and quantity | The right part numbers, in the quantity ordered | Count against the order and the packing list |
| Dimensions | Critical features meet the current drawing | Measurement on a sample, focused on critical characteristics |
| Appearance and finish | No damage, corrosion, coating defects or contamination | Visual inspection under good light, against agreed standards |
| Fit or function | The part fits or works, where that can be checked | Gauges, fixtures or functional tests where specified |
| Identification | Marking and labels are correct and legible | Check against the drawing and the customer's labelling requirements |
| Packing | Parts are protected and packed as agreed | Check packing method, quantity per pack and labelling |
| Documents | The paperwork the customer requires is complete | Check inspection reports and any required certificates |
Sampling: how much to inspect
Few factories inspect every part at PDI, and for many products there is no need to. Most PDIs inspect a sample and accept or reject the lot based on what the sample shows.
Sampling plans are often agreed with the customer. Many are based on standard tables, such as those in ISO 2859-1, which set a sample size for a given lot size and an acceptable quality limit (AQL). Whatever the method, it should be written down and applied consistently, so that a lot accepted on Monday would also have been accepted on Friday.
Some characteristics justify checking every part regardless: safety-critical features, features with a history of problems, or anything the customer specifies for full inspection.
PDI vs stage inspection
PDI is sometimes expected to do the job of stage inspection. They are different checks with different purposes:
| Aspect | Stage inspection | Pre-dispatch inspection |
|---|---|---|
| When | After each operation that can introduce defects | After production is complete, before dispatch |
| Question | Did this stage do its job correctly? | Is this order ready to ship to this customer? |
| Scope | One stage, one batch | The whole order, including packing and documents |
| Good at | Catching defects early and finding causes | Confirming the shipment, and catching final damage or mix-ups |
| Poor at | Seeing the order as a whole | Finding root causes or defects hidden by later operations |
Some factories also run a final inspection after the last operation, separate from PDI; in smaller units the two are often the same step. Either way, PDI is most useful as confirmation of an order that was checked along the way. Quality checks before dispatch explains how stage inspection and PDI fit together.
Dispatch readiness: more than the parts
An order can pass dimensional and visual checks and still not be ready to ship. Before release, confirm that:
- Every part in the shipment has passed inspection, and any rejected or held parts have been separated out.
- The quantity matches the order, or a partial shipment has been agreed.
- Labels, packing and paperwork match each other and the order.
- Any customer-specific requirements for this order have been checked.
- Where the customer inspects before dispatch, or sends a third party to do it, that inspection has been arranged and recorded.
Recording a PDI
A PDI that isn't recorded is hard to stand behind. If a customer raises a problem weeks later, the record is what shows what was checked and what was found.
A useful PDI record captures the order and parts inspected, the lot size and sample size, the result for each characteristic checked, any deviations and what was done about them, the drawing and checklist revisions used, who inspected and when, and the decision to release or hold.
The revision matters more than it seems. A PDI carried out against an outdated drawing confirms the wrong thing. Document and revision control on the shop floor covers how to keep inspection criteria current.
When an order fails PDI
- Hold the order and keep it apart from material that is ready to ship.
- Decide whether to sort, rework, scrap or ask the customer for a concession, and record the decision.
- Re-inspect after any rework, against the same criteria.
- Trace the defect back to the stage that produced it, and find out why that stage's check missed it.
The last step is the one most often skipped, and it is the one that stops the same failure recurring. Production tracking by stage shows how stage records make that trace possible.
Common PDI mistakes
- Treating PDI as a signature. A name on a delivery note without a recorded check protects nobody.
- Inspecting what is easy rather than what matters. Measuring overall length is quicker than checking hole positions, but the hole positions are what the customer assembles to.
- Checking against an old drawing or checklist.
- Skipping packing and labelling because the parts themselves passed.
- Sampling that changes with workload instead of following the agreed plan.
- Making PDI the main filter. If PDI regularly rejects orders, the problem lies upstream.
- Rushing at month-end, when dispatch pressure is highest and PDI is the easiest step to compress.
Digital PDI workflows
On paper, a PDI is a form filled in at the end of the line, and its link to the order depends on someone filing it. In a digital production and quality system, PDI is a step in the order's workflow: the checklist for that part is available at inspection, results are recorded against the order, and the order's dispatch status shows whether PDI is complete.
Rules about what must happen before release can be built into the workflow, which is where workflow automation helps. The inspection decision itself stays with the inspector.
PDI in Budve SmartFlow
In Budve SmartFlow, the manufacturing production and quality management system Reinstate Labs designed and built, PDI and dispatch form one of the system's core modules, next to production, quality management and document control. Quality follows a stage-wise workflow through the unit's processes, from pressing and bending through five welding stages to painting, so the final check sits in the same system as the production and quality records that come before it.
Conclusion
PDI is the last point at which a manufacturer can stop a problem reaching the customer, and the record of what was shipped. It is most effective when it is planned, consistent, recorded against the order and made against current documents, and when it confirms an order that was already checked at each stage.
See our manufacturing page for how PDI fits into a wider production and quality system.