Calculating Female Cavity Depth and Counter Clearance from Measured Paperboard Bulk
Female cavity depth equal to compressed bulk caliper and counter clearance matching substrate compressed thickness prevent fiber shear during embossing.
Paperboard Bulk
Material Efficiency
Volumetric efficiency in paper manufacturing represents the ratio of a material’s thickness to its weight per unit area. This paperboard bulk acts as a primary indicator of the stiffness and cushioning properties of a packaging grade. High bulk materials provide greater structural strength for a given weight, allowing for the production of lightweight containers that do not sacrifice protection.
Structural Measurement
Measuring this property involves dividing the caliper of the sheet by its grammage to determine the specific volume. While two different grades might have the same weight, the paperboard bulk will vary depending on the fibre type and the level of refining used in the pulp mill. Mechanical pulps often yield higher bulk than chemical pulps because the fibres are more rigid and do not pack as tightly.
Performance Selection
Carton manufacturers select high bulk grades to achieve the necessary bulge resistance in larger boxes without increasing material costs. This characteristic also influences the tactile feel of the finished product and its performance during the die cutting and creasing stages. If the paperboard bulk is too low, the resulting package may appear flimsy or fail to maintain its shape when stacked in a retail environment.
Maintaining the target thickness ensures that the board runs consistently through high speed automatic filling lines.