Creasing Geometry
Steel dies press into a substrate to create a defined line of structural weakness for folding. During the conversion of heavy cartons, male rule penetration refers to the depth at which the raised metal rule enters the female matrix or channel. Correct adjustment of this depth ensures the board delaminates internally without rupturing the outer liner.
If the rule sits too high, the crease remains shallow and the carton resists folding or exhibits spring back.
Operational Tolerance
Setting the height of the cutting and creasing plate requires precision to within a few microns. When male rule penetration is too aggressive, the tool cuts through the top layer of the board, leading to a cracked fold that ruins the shelf appearance. The width of the female channel must be calculated based on the thickness of the board and the width of the male rule to allow space for the displaced material.
For a board of 400 microns, the channel width is typically the rule width plus 1.5 times the board thickness. Proper alignment prevents the rule from striking the edges of the channel, which would dull the tool and create uneven pressure across the sheet.
Failure Mode
Insufficient pressure results in a rounded fold that interferes with the performance of high speed filling machines.
