Air Coupled Ultrasonic Guided Wave Measurement for Board Crease Integrity
Air-coupled ultrasonic guided waves quantify paperboard crease ply delamination and micro-cracking non-destructively, preventing box compression failure.
Clearance Ratio
Cutting Precision
Distance between the punch and the matrix in a die cutting assembly determines the quality of the sheared edge on paperboard. The clearance ratio describes the horizontal distance between the cutting edge and the die opening expressed as a percentage of the material thickness. It dictates whether the board snaps cleanly or develops a ragged edge with excessive dust.
Optimal settings vary based on board density and moisture content.
Shear Quality
Proper alignment ensures that the fracture starts exactly at the pressure point and travels cleanly through the entire thickness of the substrate without deviation. When the clearance ratio is too low, the cutting tool experiences increased wear and requires higher force to penetrate the surface. This leads to double shearing where two distinct fracture lines appear.
A high ratio causes the board to bend into the die opening before the cut occurs. This creates a burr. Excessive clearance also creates a crushed edge that absorbs more moisture or adhesive than the rest of the board.
The resulting lip interferes with stacking and downstream feeding in automated packaging lines.
Tooling Longevity
Wear patterns on steel rule dies often indicate whether the setup maintains the correct distance during high speed operation. Maintaining the clearance ratio extends the life of the cutting faces by reducing lateral pressure. This prevents damage.
Lubrication and temperature control prevent the steel from expanding and changing the gap. Precise tooling avoids the generation of loose fibres that contaminate print heads or adhesive nozzles.