Calculating Substrate Compression Ratios in Embossing Operations
Substrate compression ratio measures z-axis compaction, balancing tool impression depth against fiber strain limits to maximize embossing height without shearing.
Platen Nip Force
Operational Pressure
Vertical load applied across the contact area between two flat surfaces in a die-cutting or embossing press determines the crispness of the finish. Platen nip force is the total tonnage exerted when the moving plate reaches the end of its stroke against the stationary bed. Applied pressure must be sufficient to drive the steel rules through the board or to deform the fibers into the shape of an embossing die.
If the force is insufficient, the waste material will not strip cleanly from the carton blanks.
Leveling the Press
Leveling the press through the use of thin paper shims, a process known as make-ready, ensures that the pressure is uniform across the entire sheet. Variations in the leveling can cause some areas of the die to cut too deep, damaging the cutting plate, while other areas fail to cut through the linerboard. Modern presses use electronic load cells to monitor the total pressure and prevent the machine from exceeding its mechanical limits.
The hardness of the anvil or the thickness of the cutting blanket also affects how the energy is transferred into the substrate. Excessive force often leads to the premature wear of the cutting rules or the localized crushing of the board structure.
High-density Boards
High-density boards require more energy to shear than lightweight recycled grades. The choice of force level depends on the total length of the cutting rule and the complexity of the design. Proper calibration prevents the structural failure of the folding carton during the assembly phase.