Nordson Extrusion Dies Industries will showcase a new generation of the contour cast film die which now incorporates an internal deckle that is said to enable extrusion processors to achieve the speed and precision without incurring downtime for changing product width.
According to the company, there are two major advantages of the Contour Die over traditional dies with "coathanger" manifolds: firstly less time needed to achieve on-spec product and to purge between product runs; and secondly up to 25% improvement in cross-directional product uniformity, along with a reduction in gel formation. The new-generation Contour Die is said to retain these advantages while saving up to two days of downtime for width changes because it incorporates an internal deckle for making changes in product width.
In developing the original Contour Die, Nordson Edi designed a coathanger-shaped manifold, which produces a streamlined melt flow. Unlike the block-like shape of traditional coathanger dies, the Contour Die has a "sculpted" configuration that is smaller and tapered at the ends. This unique shape offsets the differences in die-body deflection across the width of the die that are caused by the great pressure of the molten polymer that the extruder continuously charges into the manifold — differences that in traditional coathanger dies cause gauge variations and the product deformation known as "clamshelling".
Because it exhibits uniform die-body deflection, the original Contour Die can be adjusted to achieve on-specification film more quickly than the traditional coathanger die while still yielding a streamlined flow. In addition, it produces a more uniform cross-directional gauge profile and a more uniform layer structure in coextrusion.
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Contour die (photo: Nordson Extrusion Dies Industries)
