Standard Laboratory Test Methods for Paperboard Physical Property Verification
Paperboard physical property verification requires strict ISO 187 conditioning and standardized test methods to ensure compliance and prevent customs holds.
Crease Factor
Folding Resistance Ratio
Packaging board converting performance depends on the ratio of uncreased bending stiffness to creased bending force required to form a ninety degree fold. High quality folding boxboard relies on crease factor measurements to verify that creasing matrix setup properly breaks internal fibre bonds without fracturing top liners. Values above standard operational baselines indicate clean hinge formation that prevents carton bowing on high speed automated packaging lines.
Lower ratios signal insufficient internal delamination, which forces converting equipment to push against residual board memory and causes side wall bulging in finished cartons.
Board Deformation Behavior
Matrix depth and rule thickness establish the delamination plane within multi-ply paperboard structures. When male creasing rules compress substrate layers into female channels, shear stresses sever internal hydrogen bonds across middle plies. This engineered structural failure reduces the force necessary to maintain folded panels at right angles during gluing.
Variations in moisture content or furnish composition alter how effectively creasing tools induce shear, directly impacting crease factor consistency across paper machine reels.
Packaging Line Threshold
Automated cartoning machinery encounters operational jams when folding resistance exceeds mechanical actuator limits. Excessively high forces spring open glued end flaps before cold adhesive or hot melt sets completely. Correctly calibrated creasing operations maintain structural integrity without sacrificing line efficiency.