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.
Board Grammage
Mass Definition
Mass per unit area expresses the physical mass of paper board measured in grams per square metre under standard atmospheric conditions. A standard conditioning environment of twenty-three degrees Celsius and fifty percent relative humidity stabilizes sample moisture before precision balance weighing takes place. In commercial folding boxboard transactions, board grammage establishes the primary billing metric and sets structural baseline values for bending stiffness and box compression strength.
Target values govern production parameters at the paper machine, where stock jet velocity and wire speed adjustments dictate sheet mass uniformity across the machine direction.
Measurement Protocol
Precision die cutters isolate exact surface areas from sample rolls to calculate unit mass across the web profile. Technicians weigh multiple specimen strips across cross-machine directions, recording mass variations against mill specification sheets. Density variations alter bulk yield without changing overall weight, making caliper cross-checks necessary during quality verification.
Automated scanners mounted on paper machines monitor mass profiles continuously, applying air-knife dampening or stock valve corrections whenever profile deviations exceed two percent of nominal target values.
Tolerance Boundary
Permissible deviation limits define the commercial trade acceptance window for raw material consignments. Mills deliver rolls within strict percentage bands around nominal mass targets, typically maintaining tolerances between plus or minus three percent for solid bleached sulphate grades. Exceeding lower grammage thresholds reduces structural carton integrity, causing creasing failure on high-speed filling lines.
Exceeding upper grammage limits increases transport costs and mill raw material consumption without adding proportional commercial value to converted packaging units.
Verification of Paperboard Chain of Custody Public Scope Schedules
Public scope schedule verification requires matching board product categories and claim systems on official registers to downstream delivery notes.