Dynamic Fracture Mechanics of Multi Layer Paperboard Creasing under Rapid Shear Loading
Rapid shear creasing requires tailored interply delamination toughness to prevent liner fracturing while reducing folding torque on high-speed lines.
Male Scoring Rule
Creasing Tool
Steel blade inserts are used in die-cutting machines to form controlled crease lines in paperboard substrates. The male scoring rule is a radiused steel blade that pushes the paperboard into a matching female matrix channel. This action creates a precise hinge that allows subsequent folding without erratic surface cracking.
Deformation Mechanism
Delamination within the board occurs during the stroke when the steel edge forces the outer plies into the groove. This concentrated pressure shears the internal bonds of the multi-ply board, creating a localized roll or bead on the inside of the carton. By pre-damaging the fiber matrix in a controlled manner, the male scoring rule ensures the outer printed surface stretches smoothly rather than tearing when the panel is folded.
This deformation is critical to maintaining a clean appearance along the folded edges of cosmetic and pharmaceutical packaging.
Score Dimension
Choosing the correct rule thickness is determined by the caliper and density of the specific paperboard batch. For thick or high-density board, a wider male scoring rule must be paired with a wider female channel to prevent excessive shearing. If the blade is too narrow or sharp, it cuts into the surface fibers of the board rather than forming a rounded crease.