OPTIMIZATION OF COAT-HANGER DIE USING 2-WAY FSI AND ADJOINT METHOD

Abstract

The coat-hanger dies are extensively utilized in the plastic film and sheet extrusion sector. The product's quality and the extrusion machine's power requirements are contingent upon the flow uniformity at the die exit and the amount of pressure drop, respectively. Designing a die that can provide uniform flow at the die exit and minimize pressure drop is challenging for die manufacturers. This study investigated the die utilized by a local polypropylene sheet manufacturer. It enhanced the die's design regarding deflection at the exit, uniformity of outlet velocity, uniformity of shear rate at the walls, and pressure drop. This was achieved by employing Scheme Programming Language and the licensed CFD package, Ansys FLUENT Workbench 2020 R2, based on the finite element method. The rheological characteristics of the polypropylene were characterized using the Power law, Cross law, and Carreau-Yasuda viscosity model. The FSI analysis results indicate that by raising the die body thickness to 100mm and reducing the number of supports to 4, the deflection at the exit is reduced to 1.03%. Furthermore, the analysis of the simulation results acquired using the adjoint optimization method showed that the optimized die design outperforms all three aspects by ensuring uniform exit velocity, wall shear rates, and reduced pressure drop.