Interply Delamination Energy Thresholds during High Speed Converting of Recycled Paperboard Grades
Matching dynamic Scott Bond energy above 120 J/m² prevents high-speed folder-gluer delamination and reduces net carton cost through lower line scrap.
Dynamic Fracture Energy
Impact Limit
Measurement of the kinetic work required to propagate an existing crack through a running paper web or board substrate under rapid loading provides a critical index of structural integrity. This dynamic fracture energy determines the vulnerability of paper to sudden web breaks under high tension. The property is quantified in joules per square metre, representing the energy absorbed as a fracture lines across the fibres.
It establishes the operational threshold above which high-speed web presses and folder-gluers cannot run without risking catastrophic material failure, separating stable runs from those plagued by frequent stops. It is tested using specialized pendulum testers that strike the material at velocities mimicking actual press runs, providing a realistic measure of how the paper behaves under sudden shock.
Stress Propagation
Elastic deformation precedes the actual structural separation when a moving paper web experiences localized tension spikes. Under rapid loading, dynamic fracture energy reflects how the fibre network distributes localized strain before the crack tip advances. High-yielding chemical pulp fibres increase the value by establishing dense hydrogen bonding, whereas mechanical pulp or mineral fillers reduce the network elasticity.
This molecular response dictates whether a minor edge nick remains stable or spreads instantly into a complete break.
Conversion Performance
Modern rotogravure and flexographic printing presses run at speeds that demand tight control over web tension to maintain register accuracy. In these environments, monitoring dynamic fracture energy ensures that reels can withstand sudden accelerations without tearing. Low energy values correlate directly with web breaks during reel changes or rapid speed adjustments.