Standard Crease Depth and Rule Height Calculation for Multi-Ply Boxboard
Calculate crease rule height by subtracting compressed board caliper from cutting rule baseline, sizing matrix width to rule thickness plus 1.5 to 1.8 times board thickness.
Crease Depth Calculation
Geometric Assessment
Predicting the quality of a fold in corrugated or solid board requires a mathematical analysis of the depression made by the creasing tool. A crease depth calculation determines the distance the creasing rule must travel into the substrate to create a reliable hinge without fracturing the liner. This value is derived from the total thickness of the board and the specific density of the material.
A shallow crease leads to high folding resistance and potential spring back on the packaging line.
Tooling Specification
Engineers use these figures to select the correct height of the creasing rules relative to the cutting blades in a die. The crease depth calculation accounts for the compression of the fluting and the displacement of the fibres into the female matrix. If the depth is too great, the material suffers from internal shear which weakens the finished box.
Precise settings ensure that the board delaminates internally to form a bulb, which is the necessary structural change for a clean bend.
Structural Integrity
Achieving the correct ratio between depth and width is essential for the durability of the container. A calculation that ignores the moisture content of the board will often produce inaccurate results, as dry fibres are more brittle and prone to cracking. Correct depth ensures that the packaging can withstand the mechanical stress of palletisation and transport.