The US-based extrusion equipment manufacturer Nordson EDI has produced a 9-manifold flat die for producing 9-layer film from various resins, an innovation which the company claims is “the first of its kind”. Nordson EDI’s chief technologist, Sam Iuliiano says that, while the degree of improvement will vary with the application, in general its 9-manifold die technology promises to reduce variation in individual layer thickness from the +/- 15% tolerance often encountered with comparably advanced feedblock systems to +/- 5%.

“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. “Engineering a 9-manifold die was a big challenge for us, since 10 major die body segments had to be adequately fastened and heated. In addition, the nine flow channels were each custom designed for the specific layer that they were distributing, meaning that we had to accommodate flow channels of varying sizes and layouts in the design.”

The multi-manifold method provides greater layer uniformity and thickness accuracy because 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.

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