Analytical and Numerical Methods for the Design of Maddock Mixers in Single Screw Plasticizing Technology

Abstract

Summary: In single screw plasticizing technology dispersive mixing elements, i.e., axial and spiral Maddock shear heads, are often used to improve the melt quality. Mathematical models are necessary to efficiently design the mixing section. An analytical model for the design of Maddock mixers is presented in this work. In addition, a CFD‐software package is employed to determine the flow and pressure field for different geometries and processing conditions. For the design and process analysis of fluted dispersive mixers the validity and potential of simplified analytical solutions are compared to more versatile and detailed CFD‐simulations.

A Global Model for Starve-Fed Nonconventional Single-Screw Extrusion of Thermoplastics

“…Rectangular channels were assumed in the calculations, and the mesh density was very low. Simplified analytical solutions and detailed computational fluid dynamics CFD simulations were recently compared by Olbrich et al 31 In this paper, ANSYS-Polyflow CFD software 32 has been used for modeling of the melt flow in the mixing screw to develop screw pumping characteristics, which were implemented into the global model of the starve-fed extrusion process. A real geometry of the mixing element has been modeled including entrance and exit regions.…”

“…Rectangular channels were assumed in the calculations, and the mesh density was very low. Simplified analytical solutions and detailed computational fluid dynamics CFD simulations were recently compared by Olbrich et al …”

Three-dimensional finite element method simulation study of fusion screw geometry

“…Therefore, it is not surprising that considerable effort is spent to study mixing and different types of mixing elements. [1][2][3][4][5][6][7][8][9][10][11][12] In principle, there are two main mixing mechanisms. The first one, so called dispersive mixing, is based on lowering of the size of mixture components.…”

“…The second one is distributive mixing, which redistributes the particles through the volume. 1 Distributive mixing is very useful for blending of polymers with similar viscosities. Distributive mixing is typically caused by any change or interruption of velocity in the screw channel.…”