Optimizing Creasing Rule Geometry for Coated Paperboard Packaging
Optimizing creasing rule tip radius and channel geometry enables controlled internal board delamination, eliminating coating cracking and springback jams.
Crease Springback Angle
Resistive Force
Angular measurement of folding resistance defines the tendency of a creased paperboard to return to its original flat state. The crease springback angle measures the residual elastic force that acts against a fold after it is made. High values in this property indicate that a carton flap will exert continuous outward pressure against a glued seam during assembly.
This behaviour often leads to adhesive failure on high-speed packaging lines.
Material Composition
Physical properties of the wood fibres determine how well the board retains its folded shape. Long softwood fibres maintain higher elasticity, which contributes to a larger return force. Adjusting moisture during converting helps to reduce this resistance by relaxing cellulose bonds.
Machinery Interaction
Packaging equipment requires precise control over flap forces to ensure reliable carton sealing and gluing. When the return force is too high, cartoning machines fail to hold the flaps in position long enough for the adhesive to set properly. This mismatch causes jammed machines and frequent line stoppages.
Measuring the force at a standardized time interval allows packers to predict runnability and adjust the compression time on the filling line. Operators often increase glue volume or extend compression belts to compensate for uncooperative boards.