Stress Response
High-speed mechanical stress applied to paperboard during converting causes immediate changes in its dimensional stability and thickness. When a sheet undergoes dynamic deformation under the pressure of a creasing matrix or a printing cylinder, its internal fiber bonds yield to the stress. This behavior determines whether the board will fold cleanly or crack along the crease line during automated assembly.
Press Behavior
Rapid compression in the nip of a flexographic or offset press subjects the substrate to forces that act within milliseconds. Under these conditions, the paperboard must absorb the compression and rebound quickly to its original caliper. If the material suffers from permanent dynamic deformation, the print image loses definition due to uneven pressure distribution.
This recovery capacity depends on the elasticity of the fiber network and the presence of mineral fillers. Modern presses operate at speeds that demand instant recovery, meaning that slower-reacting fibers will cause continuous registration problems during multi-color runs.
Structural Failure
Excessive pressure causes delamination between the plies of a multi-ply board, destroying its structural integrity. When the elastic limit of the fiber bonds is exceeded, the internal structure ruptures. This localized collapse weakens the board, leading to fluted edges or failed corners in the finished carton.
Proper control of the press settings prevents these defects by keeping the forces within the material’s elastic boundary.
