Simulation of Non-Isothermal Non-Newtonian Flow Behavior of PP for Various Injection Molding Screws and Comparison with Experimental Results

Abstract

Reducing injection molding cycle time is very important for improving productivity. In the cooling phase of injection molding, resin plasticization must be completed in the screw. This study examined the plasticization and flow behavior of polypropylene in injection molding screws using non-isothermal simulation. A standard screw and two types of barrier screws, the open-type, in which the barrier flight is open, and the closed-type, in which it is closed, were used. The geometry used in this simulation was wound using a channel model for a full three-dimensional flow simulation. Through non-isothermal simulation, the pressure distribution, melt flow, and temperature distribution were compared in terms of screw design. The experimental study revealed that in the open-type of the barrier screw, the solid bed and melt pool were well separated by the barrier flight, allowing for better melting than in the standard screw and the closed-type barrier screw. Simulation verified that resin melted better in the open-type barrier screw due to its easy inflow in the barrier flight and high temperature generation in the screw channel. The simulation results proved that the study of simulated flow and plasticization of resin in a screw is very useful for estimating screw performance.