The useful question about quality control is not “do you inspect?” Every factory says yes. It is “at which points, measured how, and what happens when the number is outside the limit?” Here is how a run works at our plant, gate by gate.
Gate one: incoming material
Board arrives with a mill certificate stating grade and grammage. We check grammage with a cutter and a balance, check the batch against the approved material, and check caliper on greyboard. A wrong grammage does not fail immediately — it fails in the customer's hands, when the box is thinner than the one they approved.
Roll and sheet stock is also checked for moisture and for visible surface damage. Damp board creases badly and no amount of press skill will fix it.
Gate two: first-off
Before the run proceeds, the first sheet off the press and the first piece off the die are measured against the approved specification, not against each other. This is the gate that decides whether the run happens at all.
| Characteristic | Method | Tolerance |
|---|---|---|
| Print register | Registration marks under loupe | ±0.1 mm offset |
| Colour | Matches approved proof or Pantone drawdown | Visual with densitometer reading |
| Cut and crease position | Caliper and steel rule | ±0.2 mm cut / ±0.3 mm crease |
| Foil and emboss position | Overlay on the dieline | ±0.15 mm |
| Window patch | Measure to cavity edge | ±0.5 mm |
| Wrap alignment (rigid) | Hand check at the seam and corners | ±0.5 mm |
| Formed cavity depth (blister) | Depth gauge on first shell | ±0.3 mm |
If first-off fails, the run stops. Setting up again costs an hour. Shipping out of tolerance costs a container.
Gate three: in-process
Every machine has a known failure mode, so sampling is aimed at that mode rather than spread evenly. On the press it is colour drift and hickies. On the die-cutter it is nicks, crease cracking and cutting into the sheet. On the gluers it is glue positioning and flap squareness. On hand assembly it is wrap alignment and corner quality.
Sampling frequency is set per job: typically every few hundred impressions on print, and a continuous check at the assembly table. Any finding outside tolerance triggers a hold on the pallet, a root cause, and a decision — rework, downgrade or reject — recorded before production resumes.
Gate four: final inspection at AQL 2.5
Finished cartons are sampled by lot according to the general inspection level in use, and defects are classified before anything is counted. A minor defect is cosmetic and does not affect function or the customer's perception at arm's length. A major defect affects function, print legibility, or is visible on the shelf. A critical defect is safety, regulatory or wrong-product.
- Acceptance at AQL 2.5 applies to major and minor defects combined, on the sampling plan agreed in the order.
- Critical defects are zero-tolerance regardless of lot size.
- The AQL is stated on the order, not negotiated after a rejection. If your buyer requires a different level, say so at quotation.
What in-house inspection cannot do
We do not hold an accredited laboratory. Tests we run ourselves — drop, compression, carton burst — are recorded against a protocol and can be shown to you, but a report bearing an accreditation mark has to be commissioned from a third party. Migration testing for food contact is in the same category, and it must be planned against the actual material set.
Ask any supplier two questions: what is your AQL, and who measured it. The second one separates a process from a claim.
Third-party inspection
If your program requires an external inspector at final random inspection, we will support the visit and provide the lot breakdown, the sampling plan and the retained samples. Please tell us at order confirmation rather than the week of shipment — booking an inspector takes time, and a pre-shipment window is not movable once the container is scheduled.
Need the inspection plan in writing?
Tell us the product and the market. We will put the AQL level, the sampling points and the test list into the quotation rather than leaving them to chance.
Request a quote