Determining Matrix Channel Width for Heavyweight Folding Boxboard Grades
Determining matrix channel width requires adding steel rule thickness to board caliper multiplied by 1.5 for machine direction or 1.7 for cross direction scores.
Matrix Channel Width Calculation
Geometric Determination
Mathematical formula used to select the correct size of the creasing channel ensures that paperboard folds without cracking or delaminating. The process of matrix channel width calculation relies on the thickness of the substrate and the width of the creasing rule. It provides the precise clearance needed for the material to bulge into the female die.
Formulaic Application
Standard industry practice involves multiplying the board thickness by a factor and then adding the thickness of the steel rule. For most solid bleached boards, matrix channel width calculation follows the sum of the rule thickness plus 1.5 times the board thickness. When working with corrugated materials, the multiplier increases to accommodate the flute height and the liner weight.
Choosing a channel that is too narrow results in excessive pressure and surface rupture on the outside of the fold. Conversely, a channel that is too wide produces a loose and poorly defined crease that complicates the high speed folding and gluing operations.
Production Outcome
Accurate measurements prevent the formation of surface cracks or uneven score lines during the converting run. Matrix channel width calculation remains the main tool for die makers to ensure consistent box geometry across different production batches.