Optimizing Counter Matrix Geometry for Coated Paperboard Score Performance
Matching counter matrix channel width to rule thickness plus 1.5 to 1.7 times board caliper prevents clay coating rupture and stabilizes carton score stiffness.
Ejection Rubber
Mechanical Component
Die-cutting plates that stamp out folding carton blanks require a mechanism to release the cut paperboard from the steel cutting rules. The ejection rubber is a compressible elastomeric strip or profile glued adjacent to the steel rules on a cutting die. This material compresses as the die descends to make the cut, then expands as the die rises to lift the sheet away from the sharp metal edges.
It prevents the paperboard from sticking to the die, which would otherwise cause machine jams or torn blanks. Selecting the correct density ensures that the sheet is pushed away cleanly without marking the printed surface.
Elastomeric Property
The performance of the die depends on the hardness, elasticity and rebound speed of the compound. Too much hardness can crush the edges of the carton board and damage the delicate creasing matrix. Conversely, soft materials may fail to rise quickly enough at high press speeds, which leads to incomplete release and sheet tearing.
Modern converting lines use profiled shapes that distribute the force evenly to avoid marking the stock while maintaining high throughput.
Process Durability
Repeated compression over millions of cycles causes the material to lose its resilience and permanently deform. Printers must inspect and replace these strips periodically to prevent production stoppages on high-speed folder-gluers.