Advanced Melt Rheology Control: A Filling Defects Investigation for Hot Runner Based Injection Molding

Abstract

A novel invention called Rheodrop technology is introduced for hot runner based injection molding. The technology allows control over melt rheology by applying desired shear rate values to the polymer melt during and/or in between injection molding cycles. The shear rate is applied by rotating the valve pin inside the hot drops and it is controlled by adjusting the rotational speed. The main goals are to optimize the process and to enhance the properties of molded parts. The focus on this study was incomplete filling defects which can be eliminated by the introduced technology. Numerical simulation and experimental analysis were performed to investigate the incomplete filling issue for hot runner systems. A four cavity hot runner mold was utilized in this research study and the processed material was Acrylonitrile Butadiene Styrene (ABS). Moldflow simulations was presented at three different temperature levels. The cavities were perfectly filled at the highest melt temperature level with incomplete filling resulting at the lower levels of melt temperature. Experimental results showed that implementing Rheodrop technology produces consistent ideal filling throughout the selected range of melt temperatures.