Deformation Energy
Irreversible work done during mechanical flexure dissipates localized stress within paperboard layers without causing immediate structural fracturing. Material characterization procedures analyze plastic bending strain dissipation to determine how folding boxboard absorbs mechanical energy along score lines during carton assembly. Controlled plastic deformation converts strain energy into heat and localized fiber displacement.
High plastic strain capacity enables crisp carton scoring and clean ninety-degree corner folds.
Yield Mechanics
Tensile and compressive strain behavior across outer and inner linerboard plies dictates how folding boxboard accommodates bending moments. Compression yielding on the inside fold face generates micro-delamination and localized fiber buckling, reducing outer liner tension. Long softwood kraft fibers increase plastic deformation capacity, preventing surface cracking on the outer tension side of the fold.
Mills optimize furnish layering and moisture content to enhance plastic strain capacity across machine and cross directions.
Crease Performance
High speed cartoning machines subject paperboard blanks to rapid folding operations where un-dissipated strain causes score line bursting or panel bowing. Controlled yielding within internal board layers allows sharp creasing without rupturing surface printable coatings or functional barrier films. Material exhibiting high plastic bending strain dissipation exhibits low spring-back angles after folding, ensuring square box geometry on filling lines.
Paperboard manufacturers tune multi-ply structural properties to maximize strain dissipation during high speed converting and automated packaging operations. Superior strain dissipation protects brand graphics and barrier layers from cracking during automatic flap folding.
