Ultrasonic Wave Attenuation Basics for Paperboard Creasing Quality
Non-destructive ultrasonic wave attenuation evaluates paperboard crease quality by measuring acoustic energy loss caused by internal shear delamination.
Crease Depth Ratio
Metric Definition
Die-cutting and scoring tolerances define the relative penetration of a creasing rule into a paperboard substrate against the uncompressed caliper of the sheet. In carton converting, crease depth ratio quantifies the relationship between rule penetration depth and total board thickness. The calculation establishes whether the internal fibre plies have undergone sufficient shear separation without rupturing the surface liner.
Proper execution creates an internal hinge mechanism while maintaining the visual integrity of outer printed coatings on high-speed folding boxboard lines.
Tooling Setup
Tooling geometry directly controls this relationship during the platen or rotary converting pass. Machine operators set the crease depth ratio by balancing rule height, counter-die channel depth, and channel width against the measured board caliper and grain direction. Values between forty and sixty percent of board caliper represent the operational standard for multi-ply solid bleached sulphate and coated recycled board.
Inadequate rule penetration leaves internal plies intact, generating excessive opening resistance on automatic carton gluers. Excessive penetration cuts directly into the tension liner, producing cracked print surfaces and aesthetic rejection at retail display.
Mechanical Function
Internal ply delamination during scoring lowers bending force without sacrificing carton panel squareness. When paperboard folds along a properly proportioned score line, the inner plies delaminate cleanly in shear, collapsing inwards to form an intact roll that cushions tensile strain on the exterior print surface. High-speed cartoning machines running above six hundred packs per minute rely on this mechanical yield to guarantee jam-free erection and consistent closing flap alignment.