Delamination Shear

Mechanical Property

Planar shear resistance within multi-ply paperboard defines the internal structural capacity of the material to resist ply separation under transverse tearing forces. Standardized laboratory testing measures delamination shear as the peak force required to fracture fibers or inter-ply bonds parallel to the sheet surfaces. The property governs how solid bleached sulphate, folding boxboard, and coated recycled boards behave during high-speed scoring, folding, and gluing operations.

Resistance fails completely when individual plys shear apart under mechanical stress, causing blister formation or open carton seams.

Converting Impact

Converting equipment exerts localized rotational shear across creases when cartons travel through modern folder-gluers at rates exceeding four hundred meters per minute. High delamination shear prevents board layers from separating internally during ninety-degree and one-hundred-and-eighty-degree pre-breaks, preserving clean score integrity. Inadequate shear strength causes uncontrolled delamination across the creasing bead, yielding soft carton corners, poor stack strength, and line jams on automated retail cartoning machines.

Testing Parameter

Dynamic internal bond testing applies an accelerated pendulum or falling weight to split a sample adhered between two metal fixtures. Measured values appear in joules per square meter. A low reading signals weak wet-end ply adhesion, improper starch spray application, or excessive refining of outer plys at the board machine.

A series of grey composite and wooden test blocks rests on a concrete bench in an industrial quality assurance facility.

Carton Opening Force Surface Slope Sdq Springback Angle

Quantifying Surface Elevation Variance along Score Lines Using Optical Profilometry

Optical profilometry quantifies score elevation variance down to sub-micron resolution, identifying die wear and coating micro-fractures before carton assembly.

Machined steel doctor blade segments rest on a folded dark substrate within a pool of high viscosity black aqueous coating.

Shear Viscosity Flexural Stiffness Surface Tension

Dynamic Surface Tension and Extensional Viscosity Interdependence in High Speed Creased Paperboard Converting

Balancing dynamic surface tension sub-10ms wetting with high extensional viscosity prevents droplet rebound and glue stringing on creased paperboard.

Digital render displays several white folding paperboard cartons arranged on a dark surface alongside an open box revealing fibrous padding.

Moisture Equilibrium Tensile Strength Bending Stiffness

Optimizing Folding Boxboard Structural Stiffness for High Speed Retail Packaging

Optimizing folding boxboard stiffness requires balancing BCTMP core bulk with chemical pulp outer layers to maximize moment of inertia at target carton speeds.

Two blank substrates stand between testing apparatus alongside piles of polymer resin pellets and stacked sheet goods.

Strain Hardening Barrier Coatings Cross Direction Elongation

Polymer Film Micro Fracture Mechanisms under High Strain Shear in Folding Boxboard Creases

High strain shear during boxboard creasing causes polymer film micro fractures when local elongation exceeds film yield capacity along the outer bend radius.

An industrial render features a vernier caliper measuring a rigid material slab alongside rolled paperboard substrates and a white fiber block.

Crease Resistance ISO 5628 Polyolefin Skin Layer Score Line Cracking

Matrix Channel Width Calibration for Matte Co-Extruded Film Converting

Calibrating matrix channel width to rule thickness plus 1.6 times composite caliper prevents matte skin fracture on co-extruded film laminated paperboard.

A hydraulic press applies extreme vertical pressure to a dense stack of grey paper sheets and square cut waste fragments.

Recycling Loops Length Weighted Average Length Matrix Channel

Fibre Length Loss across Recycling Loops and Score Cracking

Recycled fibre shortening and hornification limit bending strain, requiring wider matrix channels and virgin top layers to prevent score cracking.

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