Piezoelectric Stress Wave Analysis in Rotary Die Scoring Operations
Piezoelectric stress wave monitoring detects cartonboard score cracking in real time by capturing high-frequency elastic strain transients at rotary die nips.
Female Groove Geometry
Channel Specification Profile
Physical dimensions and the cross sectional shape of the channel in a creasing matrix determine how a paperboard substrate deforms under the pressure of a rule. Proper female groove geometry ensures that the board fibers are stretched and compressed into a controlled hinge without rupturing the surface liners. The width and depth of the groove must be matched precisely to the board thickness and the width of the creasing rule.
This geometric relationship is the primary factor in determining the folding force required for a carton.
Width Calculation
Industrial standards typically set the groove width at one point four times the board thickness plus the rule width. This formula creates enough space for the board to bend into the channel without being pinched or sheared.
Depth Impact
Shallow channels fail to create a distinct hinge, while excessive depth can lead to a lack of support for the shoulders of the crease. Most matrix systems use a depth equal to the board thickness to ensure a clean result. Material choice for the groove walls, such as presspahn or plastic, affects the durability of the shape over millions of impressions.
Worn edges on the groove result in rounded creases that cause the carton to lose its structural rigidity.