Varying transition zone manifold

An extrusion die comprising a flow channel providing fluid communication from a flow channel entrance to a flow channel exit orifice, wherein said flow channel comprises a multi-stage transverse flow-providing manifold, and a downstream channel portion including said exit orifice, and wherein said multi-stage manifold spans a width;

• wherein along the manifold width, said multi-stage manifold comprises a first manifold portion comprising opposing transition surfaces having an angular relationship to each other and forming a transition zone comprising a varying included angle, and coterminous with said first manifold portion, a second manifold portion comprising opposing transition surfaces having an angular relationship to each other and forming a transition zone comprising a constant included angle.

An extrusion die comprising a flow channel having a width and a length, wherein said flow channel further comprises a transverse flow-providing manifold having a back line and a downstream channel portion including an exit orifice terminating in an exit edge;

• wherein along the flow channel width, said manifold comprises opposing transition surfaces having an angular relationship to each other and forming a transition zone, wherein one of said opposing transition surfaces intersects a surface of said downstream channel portion to form a common boundary curve;
• and
• wherein along a portion of said flow channel width, said transition zone comprises a varying included angle related to flow channel geometry, and said varying included angle prescribes a parallel or generally parallel relationship of said common boundary curve to said exit edge, or prescribes a flow channel length ratio of, or about 1:1 substantially along the flow channel width.