Sizing Female Matrix Channels for Uncoated Folding Boxboard Grades
Uncoated folding boxboard requires matrix channel width equal to creasing rule thickness plus 1.8 times caliper to prevent top liner cracking during folding.
Matrix Channel Sizing
Channel Selection
Die-cutting tooling parameters govern the precise width and depth of synthetic creasing channels used on cutting platens to form score lines in folding boxboard. Proper matrix channel sizing ensures that creasing rules push paperboard fibres into a channel of exact dimensions to create clean delamination without rupturing surface liners. This calculation applies exclusively to flatbed and rotary die-cutting systems using counter-creasing matrices or steel counter-plates.
Score Formation
Calculating channel width requires adding the creasing rule thickness to 1.5 times the board caliper for solid bleached board, or 1.7 times the board caliper for recycled folding boxboard. Selecting an overly narrow channel forces excessive board compression, causing surface cracking along the creasing line and increasing force required for panel folding. Conversely, an oversized channel produces a loose score line with ill-defined crease shoulders, leading to irregular carton geometry during automatic folding.
Matrix depth must match board caliper as closely as possible to provide a firm floor that stops rule travel without cutting through the bottom liner. Precision depth selection prevents score variation across wide sheet layouts during high-speed die-cutting runs.
Fit Boundary
Channel alignment tolerance restricts lateral shifting to less than zero point zero five millimetres across the creasing plate. Extreme caliper fluctuations across a mill roll compromise crease accuracy regardless of matrix selection. Mathematical channel rules fail when converting double-wall corrugated boards that require specialized press configurations.