A Semi-Empirical Approach for Developing a Profile Extrusion Die Design Methodology

Abstract A semi-empirical approach has been adopted for developing a profile extrusion die design methodology, which uses both computer analyses and experimental data to address two critical elements in profile die design: die swell and flow balance. Advanced computer modeling software including both viscoelastic and viscous flows has been developed and analyses have been extensively conducted during this effort. Computer modeling assists in the following efforts: developing a fundamental understanding of the viscoelastic behavior in profile extrusion, i.e., the significant die swell phenomenon that occurs at the die exit; quantifying the land length or memory effect requirement; and providing quantitative information on the flow balance inside the die. Three different levels of viscous flow models have been developed for analyzing the flow balance inside the die, 1D, 2-1/2D, and 3D, providing different levels of detail regarding die design. However, there are limitations on using viscoelastic modeling to predict 3D die swells with today’s technology, which makes the experimental approach effective for measuring die swells in both the thickness and the width directions under different processing conditions. This is ideal for generating the extensive die swell information that is required in the design charts for various flow rates (shear rates) and draw speeds. The experimental die swell information and the 1D flow balance model have been fully integrated and have been implemented on a PC for use by the tooling designer in conducting quick profile die design synthesis. The complementary nature of the computer modeling and the experiments has resulted in the rapid development of this die design technology.