Paper cup test method transfer is required when a supplier, factory and customer laboratory need comparable results. Sending only the method title is insufficient when specimen conditioning, fixture geometry, endpoint rules, calculations and reporting differ.
This guide supports a controlled transfer study. It does not accredit either laboratory or create a universal equivalence criterion. Qualified laboratory and statistical personnel must approve the plan.
Diagnostic decision table
| Transfer risk | Control | Interpretation limit |
|---|---|---|
| Samples differ | Matched, traceable specimen allocation | Lab bias explains product variation |
| Procedure versions differ | Clause-by-clause method alignment | Same title means same execution |
| Transfer sample changes | Stability and transport control | Every difference belongs to a laboratory |
| Uncertainty is ignored | Report method capability and uncertainty | Close averages prove equivalence |
Align the intended use and method version
Define the product decision, response, unit and exact procedure revision. Compare sample preparation, conditioning, fixture, instrument range, loading or timing, endpoint, calculation and rounding. Resolve optional clauses before testing.
Document any local adaptation and whether the transfer concerns screening, acceptance or investigation. A method suitable for internal ranking may not support a contractual conformity statement. Do not call two procedures equivalent because their result columns share the same name.
Select stable and representative transfer samples
Choose material spanning the intended operating range, including normal variation without using unsafe or unidentified defects. Preserve cup construction, production time, forming position and handling. Allocate matched samples to laboratories using a randomized or balanced plan.
For destructive tests, use defensible homogeneous groups because the same cup cannot be measured twice. For non-destructive tests, determine whether repeated handling changes the specimen. Protect samples in transit and document condition on receipt.
Qualify equipment and operator readiness
Each laboratory should verify calibration, fixtures, software and environmental monitoring before comparison. Train operators from the controlled procedure and record deviations. A shared demonstration can reveal wording interpreted differently.
Run preliminary samples to identify execution failures without using those results to force agreement. Do not adjust one laboratory’s calculation after viewing the desired outcome unless the method is formally corrected and the comparison restarts under the revised version.
Compare differences and uncertainty
Retain individual results, replicate structure, invalid tests and sample identities. Plot paired or grouped differences and check whether disagreement changes across the range. Review repeatability within each laboratory as well as between-laboratory bias.
NIST notes that interlaboratory comparisons depend on design, stable transfer artefacts and appropriate treatment of uncertainty. A large uncertainty can make a simple pass statistic inconclusive. Use competent analysis and predefined acceptance rules rather than comparing rounded averages alone.
Control release and ongoing comparability
Approve the transfer only for the demonstrated products, range and procedure. Define periodic comparison, change notification and retransfer triggers such as equipment, fixture, software or method revisions. Preserve reference samples where stable and appropriate.
Send HANNAI both procedures, sample allocation and result differences when tests are being used to diagnose machine performance. This distinguishes product behavior from laboratory method differences without claiming accreditation or universal interchangeability.
Related equipment and next checks
Review the HN-S120 paper cup making machine and the related guide to destructive test measurement system study. The Engineering Notes archive connects these checks with wider machine planning.
Technical reference
- NIST: interlaboratory comparisons — general reference; confirm applicability to the installed equipment.
Frequently asked questions
Does the same method name guarantee comparable results?
No. Align the full procedure, equipment and calculations.
Can one destructive cup be measured by two labs?
No. Use justified comparable specimens and a suitable design.
Are close averages enough?
Review individual differences, range behavior and uncertainty.
When should a method be transferred again?
After relevant method, equipment, fixture or software changes.
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.