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.
Rule Height Determination
Die Calibration
Precision in the die cutting process depends on the vertical distance between the base of the tool and the edge of the creasing rule. Rule height determination is the process of selecting the correct metal strip height to ensure that the crease is formed without cutting through the board. This measurement must account for the thickness of the cutting blades and the thickness of any make ready tape applied to the press.
Material Thickness
Thicker boards require shorter creasing rules to prevent excessive pressure on the material. The rule height determination must be adjusted for every change in board weight or grade to maintain a consistent folding force. If the rule is too high, it will burst the liner of the board, while a rule that is too short will produce a weak crease that fails on the packing line.
Creasing Precision
Achieving a perfect ninety degree fold without any visible cracks is the goal of this technical setup. The rule height determination process is often done using a micrometer or a specialized gauge to ensure that every rule in a multi cavity die is identical. This uniformity is essential for high volume production where even small variations can lead to significant waste during the conversion process.