Applicator Roll
Mechanically engraved steel cylinders transfer precise, measured volumes of liquid coating or adhesive directly onto continuous rolls of paper or polymer film. A gravure coating cylinder features a pattern of microscopic cells, chemical-etched or electromechanical-cut, which carry the liquid from a reservoir to the moving web. The volume of adhesive delivered to the substrate depends on the cell depth, shape, and count per linear inch.
This configuration allows converters to achieve highly consistent, uniform layer weights during high-speed packaging runs.
Doctoring Mechanism
Continuous removal of excess liquid from the rotating surface of the cylinder ensures that only the material inside the cells is transferred to the substrate. A thin steel doctor blade wipes the gravure coating cylinder clean as it turns, establishing a uniform coating thickness. Wear on either the blade or the cylinder cells alters the transfer volume, resulting in coat-weight variation across the web.
Regular inspection of the cylinder surface maintains the required barrier performance of the laminate.
Pattern Selection
Choosing the correct cell geometry is essential for matching the viscosity and rheology of the coating liquid. Quadrangular or tri-helical patterns are preferred for thick barrier polymers, while fine screen rolls are used for low-viscosity primers.
