Creasing

/kriːsɪŋ/

General Definition

Creasing is a vital preparatory process in the Materials & Print Finishing stage, occurring immediately after printing and before the Folding (physical bending) step. This operation is designed specifically for thick board and substrate materials. Creasing involves the controlled compression of the material using crease rules to create a precise, depressed line on the surface. The main goal is to break or compress the internal fibers of the material along a specific line to prevent cracking, tearing, or damage to surface coatings like laminate or UV during the subsequent folding process.

Real-World Usage

In practical terms, Creasing is essential for any product utilizing thick cardboard that requires a three-dimensional form. This process is typically executed according to the engineered Dieline (the cut and crease pattern) developed by the Structural Design team. The resulting line is known as the Fold Line. Creasing ensures visual quality at the fold point; conversely, thinner papers usually proceed directly to the Folding step, as the risk of fiber breakage is negligible. This process is also critical because Scoring is primarily used to create a simple groove on thinner papers and, unlike creasing, does not create the necessary intentional internal fiber breakage or compression.

This process is also critical because in materials with thick coatings like cellophane or UV, creasing maintains the structural integrity of the packaging by preventing these coatings from detaching at the bend. Creasing directly affects the speed and accuracy of Folding in automatic packaging machines; precise creases ensure quick and easy assembly. If the crease line is weak or incorrect, the factory may incur significant losses, as the packaging will not form correctly on the automatic production line, stopping the filling machines.

Consultant's Note

As a technical consultant, I emphasize that the crease depth must be appropriate for the material type and thickness. Oftentimes in the industry, the creasing process is confused with Scoring. Creasing is the crucial stage situated between Dieline and Folding, and its role is to create the foundation for flawless physical bending. If creasing is omitted, especially on thick board, the Folding operation will inevitably cause breakage and damage along the fold line, harming the print.

The consultant advises that operators use tools like the Creasing Matrix to precisely control the depth and width of the crease line to provide the optimal controlled fiber damage for subsequent Folding. Furthermore, during the Structural Design stage, at least two samples with the crease must always be tested: one in dry conditions and one after exposure to ambient moisture, as moisture absorption can change the material’s stiffness and affect the final folding quality.

Packdemy Council Insight

Kevin Pinto

Strategic Advisor

Creasing creates a controlled channel in the board that allows it to fold smoothly without breaking or distorting. It is one of the most critical steps in paperboard packaging, as a good crease ensures accurate folding, proper squareness, and the correct functioning of flaps and closures. When the crease is well-executed, the board bends predictably along the intended fold line, reducing stress on the printed surface and preventing structural failures.

The quality of a crease depends on correct matching of creasing rule height, rule width, and matrix channel to the exact caliper of the board. Even small mismatches can lead to cracking, weak folds, or spring-back issues during gluing. Operators should maintain clean, consistent make-ready and check crease depth across the sheet to avoid variations that disrupt folding on the gluer. Performing a bend-test sample before full production is essential for validating the setup. A well-prepared crease improves carton performance, speeds up gluer productivity, and reduces waste significantly.

Formula for calculation of creasing matrix and creasing rule height for Board (Duplex, Triplex, Folding Box Board, PE Coated Board, Food Grade Board)

A = c
B = (c x 1.5) + d
g = f-c
A = Creasing Channel Depth
B = Creasing Channel Width
c = Material thickness (for board)
d = Creasing Rule Width (Thickness)
e = Thickness of compressed material for corrugated.
f = 23.80mm (Cutting Rule Height)
g = Creasing Rule Height

Formula for calculation of creasing matrix and creasing rule height for corrugated board.

A = e
B = (e x 2) + d
g = f-e