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.
Crease Resistance ISO 5628
Bending Moment Standard
Standardised mechanical test protocols define the bending force required to fold a pre-creased paperboard specimen through a specified angular deflection. The procedure measures the maximum bending resistance of both uncreased and creased test pieces folded to a ninety-degree angle under controlled laboratory conditions of temperature and relative humidity. By calculating the ratio between the bending force of the crease and the bending force of the uncreased board, the test derives the crease recovery ratio or crease stiffness reduction percentage.
The standard specifies test span lengths, bending rates, and clamping configurations to ensure reproducible measurement across multi-ply and solid packaging substrates. The scope stops at rigid board materials that undergo plastic or shear deformation rather than elastic flexure.
Packaging Line Runnability
Modern high-speed cartoning machines rely on predictable crease resistance to erect cartons, form square boxes, and close flaps without structural jams. If crease resistance is too high, packaging machinery cannot fold panels cleanly, resulting in carton distortion, skewed glue joints, and machine downtime. Conversely, excessively low resistance indicates ply fracture rather than healthy internal delamination, which produces weak carton corners with reduced top-to-bottom compression strength.
Measuring crease behaviour provides converters with quantitative verification that scoring tooling has properly broken internal fibre bonds without cutting the tensile plies.
Laboratory Procedure
Specimen preparation requires precision conditioning in conformance with standard atmospheric specifications prior to mechanical testing. Clamping jaws secure one end of the creased strip while a motorised loading arm applies force perpendicular to the creased axis at a constant angular velocity. Load cells record the force progression throughout the ninety-degree displacement cycle, capturing peak resistance and residual spring-back force.
Machine direction and cross direction specimens are tested separately, as fibre orientation significantly alters raw bending stiffness and the resulting crease reduction ratio.