Resiliency Rating
Resistance of folded paperboard to remaining in a bent state determines how well a carton blank can be formed and glued. The crease recovery ratio measures the force exerted by a folded crease as it attempts to spring back to its original flat position. This value determines the efficiency of high-speed folder-gluer operations and the integrity of the finished carton.
Folding Dynamic
Correct creasing weakens the paperboard along a defined line to permit easy folding without fracturing the outer liner. A low recovery ratio indicates a crease that offers little resistance, allowing the packaging line to fold the carton easily. If the recovery ratio is too high, the carton flaps will press outward against the adhesive bond, potentially popping open before the glue has fully set.
This spring back action can disrupt the sensor tracking on automatic packing lines, leading to machine jams and wasted material.
Carton Performance
Testing is conducted by holding a creased specimen at a ninety-degree angle for fifteen seconds and recording the residual force. Board stiffness, moisture content, and the depth of the creasing rule affect this return force. Setting the correct creasing depth during the die-making process ensures that the ratio falls within the narrow window required by automated packing machines.
