Co-Extrusion Dies

For the coextrusion of two polymers through a single manifold die, the thickness uniformity in the layers across the exit of the die depends on the viscosity and flow rate ratios of the polymers as well as the geometry of the die. The objective in single manifold coextrusion die design, is to determine a die geometry which compensates for polymer flow rate and viscosity effects in order to maintain uniform layer thicknesses exiting the die. An example of the coextrusion of a symmetrical A/B/A structure in a single manifold die is demonstrated below.