Creasing Rule Geometry

Production Parameter

Die makers calculate clearance between the steel rule and the female matrix based on the thickness of the material in process. This adjustment compensates for the volume of compressed pulp that must displace into the groove during the initial strike. Precision in the angle of the shoulder ensures that the board enters the opening without resistance or bunching at the edges.

Small discrepancies in the width of the tip lead to uneven folding forces, which prevents the final package from squaring correctly on high speed filling lines. Operators adjust these variables to maintain high registration accuracy during long runs of corrugated or solid board. Consistency across the entire die layout relies on uniform height tolerances within the steel rule set.

Performance Constraint

Material strain capacity dictates the limit of how sharp a fold line becomes before the surface tension exceeds the bond strength of the fibers. Excessive force at the tip causes internal delamination, which weakens the box integrity long after it leaves the converting line. Tension distributions remain fixed when the mechanical pressure remains within the elastic range of the cellulose matrix.

Correct geometry minimizes the stress concentration at the hinge by distributing the fold force across a wider contact patch. Effective score lines provide enough flexibility to fold flat while maintaining enough structural memory to resist accidental collapse under load.