Calibrating Crease Channel Width for Matte Laminated Folding Cartonboard
Matte laminated boxboard demands channel width expansion of twelve to eighteen percent over raw stock formulas to absorb film strain and prevent score rupture.
Folding Torque Measurement
Torque Evaluation
Rotational resistance testing on creased paperboard scores evaluates the mechanical force needed to fold package panels into rectangular shapes. The protocol folding torque measurement quantifies the dynamic resistance torque generated when a creased blank bends through a ninety-degree arc. Lower torque values allow high-speed cartoning machines to fold carton flaps without jamming or misaligning panels.
The test boundary covers unsealed creased samples evaluated under controlled laboratory temperature and humidity.
Test Instrumentation
Electronic bending stiffness testers clamp one side of a creased sample while a motorized arm rotates the opposite panel at a fixed angular velocity. Load cells measure resistance force continuously across angles from zero to ninety degrees. Plotting torque against bending angle reveals the peak folding resistance and the residual springback torque.
High initial resistance forces cartoning machine fingers to exert excess pressure, causing panel bowing or glue line shear. Moisture content directly alters folding torque measurement results because dry fibers exhibit higher bending resistance and brittle fracture. Optimizing matrix depth and crease rule geometry lowers folding resistance while preserving corner squareness.
Erection Stability
Uncontrolled torque variations lead to erect carton distortion and line stoppages. Consistent folding torque measurement ensures smooth running on high-speed filling lines.