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Optimal extrusion die design for production of polymer tensile test specimen

Abstract:

This work aims to present the design of an extrusion die for the production of polymeric tensile test specimens. Computational Fluid Dynamics is used during the optimization process to minimize the overall pressure drop across the die, achieve uniform exit velocity, low energy consumption, high throughput, and excellent properties of the extruded specimens. A three-dimensional incompressible viscous flow is considered and the Cross model is employed for taking into account the non-Newtonian behavior of the flow. Several geometries are analyzed before devising an optimum shape. The final design includes, in the beginning, a conical flow profile and then it gradually transitions into the rectangular cross-section of the slab. The die land is an elongated flow restriction channel of smaller cross-section, where the material experiences graduallydecreasing pressures along the length of the land and finally converging the molten polymer into a melt laminate at the exit.