Cross Direction Crease Stiffness Reduction Ratios for Solid Bleached Sulfate
Cross direction score lines on solid bleached sulfate require a 50 percent crease stiffness reduction ratio achieved via a 1.8 to 2.0 times caliper matrix width.
Liner Bursting
Failure Mechanism
The sudden rupture of the outer flat facing sheet of corrugated board under pressure indicates a major failure of packaging integrity. Occurrences of liner bursting during handling or stacking can lead to complete box failure and product damage. This mechanical failure occurs when the internal hydraulic pressure or external localized impact exceeds the tensile strength of the paperboard fibers.
Pressure Influence
Applying uniform pressure to the board surface distributes the load, but sharp points or focused forces will concentrate stress in a small area. The Mullen burst test measures the resistance of the liner to this type of localized failure by applying hydraulic pressure through a rubber diaphragm. High-quality virgin fibers and optimal fiber bonding are the main factors that increase this resistance.
Converting Consequence
Converting and shipping operations are highly sensitive to this structural failure because ruptured outer liners compromise the compression strength of the entire box. When liner bursting occurs on a cartoning line, it forces an immediate halt to clear the jammed machinery and replace the ruined packaging. Using linerboard with a guaranteed burst rating prevents these failures, ensuring that products are safely protected during transit and warehousing.
This reliability is especially critical for heavy or dense products that exert continuous pressure on the box walls.