Counter Matrix Geometry Optimization in High Speed Paperboard Die Cutting
Counter matrix channel width equals creasing rule thickness plus 1.5 to 1.7 times board caliper under ISO 534 conditioning to optimize delamination.
Dynamic Strain Hardening
Material Response
Mechanical strengthening behavior observed in polymer films and paperboard layers under rapid mechanical deformation increases resistance to further plastic deformation during converting operations. High-speed blanking and rotary die-cutting induce dynamic strain hardening as structural fibres or polymer chains rearrange under rapid loading velocities. Measurement relies on high-rate tensile testing under ISO 1924 guidelines at strain rates exceeding industrial packaging speeds.
The phenomenon ceases to govern material behavior under static loading conditions or thermal annealing.
Deformation Process
Rapid mechanical displacement reorients cellulose fibre networks along the principal axis of applied stress. Microstructural friction between bonded pulp fibres generates localized resistance, raising the instantaneous yield stress of the substrate. Dynamic strain hardening prevents localized necking during high-speed carton erecting and deep-drawing tray forming.
Polymer-coated paperboards experience alignment of molecular chains in the synthetic barrier layer under sudden impact. This structural response absorbs impact energy during package dropping and transit impacts. Converts must adjust press tooling clearances to accommodate increased peak forces caused by rapid strain rate changes during web feeding.
Rate Limit
Excessive deformation velocities cause brittle fracture when strain rates surpass internal structural relaxation rates. Low ambient temperatures reduce polymer chain mobility and accelerate fibre bond failure.