Reduced variation in individual layer thickness

A Nordson EDI nine-manifold flat die, the first of its kind, has been successfully commissioned, producing nine-layer film from various resins. While the degree of improvement will vary with the application, in general Nordson EDI’s nine-manifold die technology promises to reduce variation in individual layer thickness from the ±15% tolerance often encountered with comparably advanced feedblock systems to ±5%, according to Sam G. Iuliano, chief technologist for Nordson EDI. “This greater accuracy achievable with multi-manifold dies enables processors to run thinner layers of the costly specialty materials often required for high-performance packaging films, while at the same time enhancing product quality and consistency,” said Iuliano.

A manifold is a flow distribution channel inside the die whose complex internal geometry, engineered for a specific polymer, is designed to develop a uniform, streamlined flow and distribute the material to its full width. In a multi-manifold die, each polymer flow stream has its own manifold, and the layers are combined into a single structure only after each layer has been individually spread to its full width. By comparison, a feedblock combines multiple polymer streams into a narrow multi-layer “sandwich” that is subsequently distributed to full width in a single-manifold die. A chief reason why the multi-manifold method provides greater layer uniformity and thickness accuracy is that it avoids much of the layer-interface deformation that occurs when multiple layers pre-assembled in a feedblock are then spread simultaneously through the die.