Virgin Solid Bleached Sulfate versus Recycled Board Sourcing
Virgin solid bleached sulfate delivers superior score integrity and brightness, while recycled board reduces raw material expenditure when stiffness targets allow.
Crease Penetration
Rule Indentation
Physical displacement of the creasing rule into the paperboard thickness establishes the baseline geometry of the folding hinge. The crease penetration defines how far the male creasing rule sinks into the substrate and the female groove during the die-cutting process. It is measured as a percentage of the total sheet caliper or as a direct depth value.
Proper execution of this indentation facilitates clean, low-resistance folding on automated carton-erecting lines, and prevents the carton from bursting under pressure. In high-speed packaging, the precision of this process determines whether the machinery can form and fill the boxes without stopping.
Substrate Integrity
Excessive depth during the scoring process leads to shearing of the internal fibre plies and surface rupture. When the crease penetration exceeds the elasticity limit of the paperboard, the top or bottom liner cracks, which exposes the grey or brown middle plies and spoils the printed surface. In contrast, insufficient penetration yields a shallow crease that fails to guide the fold, causing the carton to bow or bulge.
Maintaining a balanced indentation depth is therefore necessary for high-performance packaging.
Quality Assessment
Direct measurement using cross-sectional microscopy or digital micrometers verifies the consistency of the scored channel. Technicians examine the groove profile to ensure the depth conforms to the board manufacturer recommendation, which typically falls between forty and sixty percent of the board thickness. Adjusting the backing make-ready or the rule height allows fine calibration of the crease penetration on the press.