Web Mechanics
Mechanical stress applied across the transverse direction removes the internal memory of heavy linerboard by fracturing the adhesive bonds within the fibre matrix. An anti-curl breaker bar forces the travelling web around a sharp radius immediately following the drying section of a corrugating machine. High tension combined with a small diameter roll yields permanent deformation of the paper structure, eliminating the natural tendency of coated duplex boards to roll toward the print face under ambient humidity shifts.
Tension settings on the roll stand dictate the degree of mechanical yield, where excessive force fractures internal bonds and drops the burst strength of the material below folding carton specifications.
Operation Parameters
Cylinder positioning relative to the main web path governs the depth of the wrap angle during high speed converting runs. Operators adjust the mechanical offset of the assembly to counteract varying moisture profiles across the sheet width before the die-cutting stage. Paper thickness dictates the required bar radius, ranging from small diameters for lightweight folding boxboard to larger profiles for heavy corrugated containers.
Thermal expansion across the machine width alters the effective pressure distribution, demanding precise alignment to prevent localized tearing during continuous production shifts.
Surface Effects
Residual curl reduction prevents sheet jams inside automated packaging lines by maintaining a flat plane through high speed feeding mechanisms. Smooth feeding relies on this mechanical conditioning step to ensure consistent registration during multi-pass offset lithography and subsequent foil stamping operations. Caliper retention remains stable because the induced stress concentrates solely on internal fibre relaxation rather than bulk crushing.
Finished packaging blanks processed through this mechanical stage retain dimensional stability through subsequent gluing and folding sequences.
