Acceptance Quality Limit Calculations for Corrugated Carton Lot Inspection
Acceptance Quality Limit carton inspection pairs ISO 2859-1 sampling math with physical flute and joint testing to validate lots before paper release.
Pin Adhesion
Bond Integrity
Mechanical resistance of the adhesive bond between the flute tips and the liners of corrugated board is measured by the force required to separate them. This property is evaluated through pin adhesion testing to ensure that the board does not delaminate during conversion or use. A strong bond is essential for the structural performance of the finished box.
Testing Procedure
Metal pins are inserted into the flutes of a sample and then pulled in opposite directions using a compression tester equipped with specialized fixtures. The test identifies whether the failure occurs in the adhesive layer or within the fibres of the paper itself. High pin adhesion values indicate that the starch adhesive has penetrated the liner and formed a deep mechanical anchor.
If the bond is too weak, the flutes will peel away from the liner when the board is folded or subjected to shear forces.
Production Variable
Heat transfer at the corrugator is the primary factor that determines the quality of the bond formed at high speeds. Proper gelatinization of the starch requires a specific temperature range and a consistent application of glue across the width of the web. Variations in the moisture content of the paper can interfere with the drying process and lead to localized areas of low adhesion.