Cold Foil Register Drift as the Stack Warms across a Shift
Stack thermal buildup causes substrate shrinkage and mechanical expansion, driving cold foil register drift across continuous production shifts.
Paperboard Hysteresis
Elasticity Retention
Mechanical recovery following the removal of a compressive force defines the behavior of fibrous networks under loading. This paperboard hysteresis characterizes the energy dissipation that occurs when a cellulose matrix experiences cyclic pressure. Material deformation remains path dependent because the internal hydrogen bonds shift during each compression event rather than returning to a perfect baseline state.
Hysteresis Magnitude
Print quality and structural rigidity rely on the precise degree of irreversible energy loss within a substrate. Production lines calculate this value to determine the extent of board recovery after passing through nip points or folding stations. Dense stocks composed of secondary fibers often exhibit higher variance because the shortened fiber lengths resist initial elastic deformation but fail to rebound fully.
Sheet orientation relative to the grain direction dictates the intensity of the recovery, as cross-machine direction properties typically show increased internal friction compared to machine direction stiffness. Variability in the moisture content amplifies this effect by softening the lignin binder and facilitating further fiber slip during the release of pressure. High values indicate a loss of caliper that limits the stacking strength of finished shipping containers.
Load Response
Precise control over fiber refining and sizing agents reduces the gap between loading and unloading curves. Converters specify this property to ensure that folding cartons hold their intended crease profile after die cutting. Rigid substrates maintain dimensions because the internal structure resists excessive creep over time.
Accurate measurement of this loss allows engineers to predict the long-term performance of packaging in automated filling equipment.