Fibre Mechanics
Folding boxboard performance during high-speed converting relies entirely on board runnability, a complex mechanical property profile governing web tension tolerance and bending stiffness across offset lithography and rotary die-cutting machinery. Continuous production lines demand uniform caliper and controlled moisture content within the core fibrous structure to prevent costly web breaks and misregister defects. Interlaminar bond strength directly dictates whether a multi-ply carton board survives high-peel forces exiting printing blanket cylinders without delamination.
Tensile energy absorption provides the measurable threshold for how much dynamic stress a moving paperboard web withstands before catastrophic failure halts automated packaging equipment.
Machine Tolerances
Cylinder mould forming sections and size press applications establish dimensional stability parameters during initial paper machine manufacturing. Moisture gradients transverse to the web direction cause differential shrinkage, which subsequently triggers edge curl and subsequent misfeeding on high-speed carton gluers. Converting plants mitigate these alignment deviations by conditioning substrates within strict relative humidity ranges prior to feeding automated blank feeders.
Rotary tooling clearance must accommodate caliper variations inherent in recycled fibre furnishes without inducing crushing damage to outer linerboard layers.
Line Speed
Output optimization on folding and gluing lines depends heavily on friction coefficients and surface energy characteristics of the coated paperboard exterior. Low surface energy coatings reduce adhesive transfer efficiency during high-speed nozzle application, resulting in structural joint failure under commercial distribution loads. Dynamic coefficient of friction measurements determine whether blanks feed reliably from gravity magazines without double-sheeting or stalling.
Board runnability ultimately dictates maximum operating velocities achievable across combined printing, creasing, and packaging operations without exceeding critical web tension limits.
