Paper cup board lot sampling determines which reels, pallets or sheets provide the specimens used for incoming decisions. Testing many pieces from one convenient unit does not necessarily represent the delivered lot. The lot, accessible population and selection procedure must be defined before packages are opened.
This guide supports planning with the material supplier and quality team. Apply the current purchased sampling standard and contract requirements. It does not reproduce a paid standard or provide a universal sample count for every delivery and test.
Diagnostic decision table
| Sampling question | Record required | Common error |
|---|---|---|
| What constitutes the lot? | Supplier lot, delivery units and contract identity | Mixing several productions into one decision |
| How much is accessible? | Available units and inaccessible portion | Ignoring selection limitations |
| Where were units selected? | Random or systematic selection record | Choosing only the outside or easiest reel |
| What will tests decide? | Property, method and specification | Using an average sample to describe variability |
Define the lot before choosing specimens
Use purchase, supplier and delivery records to identify the material population covered by the decision. Record grade, coating construction, dimensions, production identity and number of reels or pallets. Do not combine different suppliers, revisions or visibly separate deliveries merely to simplify the receiving form.
State whether the objective is to determine average quality, investigate within-lot variability or diagnose damage. These objectives can require different designs. ISO 186 describes representative sampling for determining average quality and explicitly notes that the method is unsuitable for determining variability within a lot.
Document accessibility and selection limits
Record which units are physically available when sampling occurs and any portion that cannot be selected. Avoid treating the front row of a warehouse stack as the complete delivery without documenting the limitation. If the purchased standard requires a minimum accessible proportion or a different agreement, follow that rule.
Prepare the selection method before seeing test results or choosing attractive material. Use randomization or the applicable systematic procedure under quality control. Preserve the unit numbers selected and replacements for damaged or inaccessible selections. Convenience substitution after inspection can bias the sample toward preferred material.
Take specimens without changing their identity
Follow the applicable standard and supplier instructions for opening, discarding protective outer layers where required, specimen location and rewrapping. Protect food-contact surfaces and avoid contamination. Keep every specimen linked to its reel, pallet or sheet group throughout conditioning and testing.
Separate sample preparation damage from delivered defects. Photograph crushed edges, wet wrapping or other incoming conditions before cutting material. Do not trim away the complaint and then report that the sampled board was satisfactory. Maintain a chain of custody for dispute or supplier-review samples.
Match the sample to each test method
Different properties can require different conditioning, specimen orientation and dimensions. Coordinate the gross sample and test-piece preparation with the laboratory. Preserve machine and cross direction where relevant. Do not use leftover pieces from one destructive test for another method if the first preparation changed them.
Record the current test standard, instrument and laboratory. Keep results by selected unit as well as the combined estimate. An overall average can meet a purchase limit while an important unit-to-unit pattern remains visible; whether that pattern affects acceptance depends on the contract and the purpose of sampling.
Make a scoped receiving decision
Compare results with the agreed specification and sampling decision rule. Record uncertainty, invalid results and any deviations from the planned selection. If the sample cannot represent the intended lot, state the limitation and obtain agreement before extending the conclusion to unsampled material.
Retain supplier and production links when releasing material to the cup line. Send HANNAI the relevant board identities, selected-unit record and forming outcomes when a machine issue is suspected. Representative incoming evidence helps separate a material-lot condition from feeding or tooling behavior without claiming that one reel describes the shipment.
Related equipment and next checks
Review the 850 roll die cutting machine and the related guide to incoming paper and coating inspection. The Engineering Notes archive connects these checks with wider machine planning.
Technical reference
- ISO 186: paper and board sampling to determine average quality — general reference; confirm applicability to the installed equipment.
Frequently asked questions
Can many sheets from one reel represent the whole delivery?
Not automatically. Select units according to the applicable lot-sampling plan.
Does ISO 186 describe within-lot variability?
Its ISO abstract states that the method is unsuitable for that purpose.
Should sampling start before defining the lot?
No. The covered population and decision objective come first.
Can inaccessible units be ignored silently?
Record accessibility limits and follow the applicable agreement or standard.
Review the evidence with HANNAI
Send your machine model, component identification and the observations described in this guide. Include the drawing or material reference and any before-and-after measurements so the required next check can be identified.