Paperboard Middle Ply Furnish Compression Mechanics under Static Bench Conditions
Middle ply CTMP bulk provides structural moment of inertia, while short-span compression bench testing quantifies network collapse risks under load.
Board Bulk
Structural Volume
Paperboard grade classification and structural yield calculations rely on a quotient representing the ratio of sheet thickness to basis weight. In technical specifications, board bulk is expressed in cubic centimetres per gram, indicating how much space a given mass of paperboard occupies. High values for this ratio mean that the sheet is thick and contains more air pockets than a highly compressed, dense sheet.
The property dictates how many sheets can be produced from a ton of pulp.
Stiffness Contribution
Flexural rigidity in folding cartons rises exponentially with sheet thickness. Consequently, board bulk determines the resistance to bulging under the weight of packed goods when a carton sits on a retail shelf. High density grades usually have lower values for this property but offer greater surface smoothness, whereas high volume sheets provide stiffness at a lower weight.
Minimizing material costs while maintaining carton integrity is the primary objective of this optimization. Mills manage the refining and pressing stages of the paper machine to preserve the internal pore structure of the sheet, thereby maximizing the thickness per unit of weight.
Converting Utility
Production machinery in a packaging plant operates within narrow tolerances for sheet height. Changes in board bulk affect the creasing behavior, scoring depth, and feeding reliability during the carton-forming process. When the volume deviates from the specification, the creasing matrix fails to deform the board correctly, leading to cracked scores or misaligned panels.