Creasing Rule Selection for Coated Folding Boxboard Conversion
Selecting steel creasing rules and matrix channels for coated FBB requires matching board caliper and CTMP core shear limits to prevent surface cracking.
Crease Moment Ratio
Folding Resistance
Folding resistance defines the mechanical torque required to form a permanent hinge in paperboard during high speed packaging conversion. Crease moment ratio quantifies this physical property by dividing the bending force of the scored channel by the resistance of the uncreased substrate. Rotary die cutting equipment relies on this proportional value to predict carton opening angles on automated filling lines.
Packaging engineers test sample blanks on pendulum stiffness instruments to establish baseline acceptance limits before production runs begin.
Torque Balance
Material stiffness directly opposes the hinge formation required for efficient carton erection. Substrate thickness and internal fibre bonding dictate how much pressure the scoring rule exerts against the anvil. Excessive bending resistance fractures the outer linerboard during the conversion stage.
Lower values prevent structural cracking while maintaining adequate box compression strength after gluing.
Conversion Limits
High grammage folding boxboard demands precise depth adjustments on platen presses to maintain the correct angular proportion. Fibre orientation across the machine direction alters the torque measurements during laboratory evaluation. Converting plants reject substrate lots that fall outside established tolerance thresholds to avoid jamming high output packaging machinery.
Proper control over this mechanical ratio ensures smooth production speeds on commercial manufacturing floors.