Helical flow of polymer melts in extruders, part II: Model simulation and validation

Abstract

This paper is a sequel to the development of the mathematical model carried out in Part I of this work. The model describes the flow of a polymer melt inside the helical channel of an injection-molding machine. In this initiative, we develop an iterative computational algorithm based on shooting Newton-Raphson method to simulate the mathematical model. The simulation results are validated against experimental data obtained from 10 different runs of an industrial injection molding machine processing two different polymershigh-density polyethylene and polyethylene terephthalate. It is observed that the simulation results are in good agreement with experimental data. This outcome demonstrates the utility of the developed mathematical model and simulation approach. From the standpoint of industrial practice, the direct benefit of this work is the ability to effectively calculate adequate shot size, recovery rate, and various state variables throughout the extent of the machine. C

Understanding the Dynamics of Polymer Extrusion: Simulation of Thermoplastics Processing with Planetary Roller Extruders

“…By varying the test parameters and recording the aforementioned sensor values in the roller cylinder, the measured data allow a validation of the simulation. Sanjabi et al have previously applied a similar validation approach based on pressure and temperature values for a single screw extruder [ 32 , 33 ].…”

Melt Conveying in Single-Screw Extruders: Modeling and Simulation

“…Several coordinate systems can be used to describe the flow along the helical screw channel. Calculations in helical coordinates have only been presented by a limited number of authors [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]; the main reason is that the governing flow equations in these coordinates are not very well established (see Section 7 ). …”

“…Several studies have used a helical coordinate system to analyze the flow of polymer melts in deep, curved screw channels [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 ]. Equivalent definitions of a non-orthogonal helical coordinate system were presented by Zamodits [ 27 ] and Tung and Lawrence [ 28 ]; while the former was applied to model curved extruder screws, the latter was used for static mixers.…”

“…Introducing further physical simplifications, Sanjabi et al [ 34 , 35 ] mathematically described the three-dimensional helical flow of a temperature-dependent power-law fluid in extruders. The governing flow equations, which additionally account for tapered screw sections, were first developed in cylindrical polar coordinates, and then transformed into a helical system.…”

Modeling of Plasticating Injection Molding – Experimental Assessment

“…In the literature is possible to find some computer models for simulation of polymer plasticating during extrusion (Tadmor andKlein, 1968, 1970;Chung, 1971;Tadmor, 1974;Torner, 1977;Tadmor and Gogos, 1979;Agur and Vlachopulos, 1982;Zawadzky and Karnis, 1985, Rao, 1986, Das and Ghoshdastidar, 2002, Béreaux et al, 2004, Khalifeh and Clermont, 2005and Sanjabi et al, 2010. The present work consists of different modifications of the extrusion model formulated by Tadmor and Klein (1968).…”