Computer aided design of extrusion slit dies

Computer aided design of extrusion slit dies has been presented. The design should ensure the melt to be distributed over the width of the die so as to maintain identical die exit flow rates and uniform physical properties of the melt at the exit. To meet these requirements a method for die dimensioning has been developed, based on the representative viscosity concept. A computer program was developed to rapidly design a slit die for assumed product dimensions, processing parameters and polymer properties: die geometry and essential polymer flow characteristics are calculated. Simulation calculations allowed to study the pressure drop in the die (Delta p), residence time (t) and temperature increase of the material (Delta T) in relation to material temperature (T), mass flow rate (G) and the width (B) and thickness (H) of the product.