Influence of injection molding parameters on the quality of structured surfaces

Abstract

The influence of injection molding parameters such as melt temperature, mold temperature and holding pressure on the look and feel of structured plastic surfaces are investigated. Therefore, an automated test stand measuring the gloss and color of the surface was developed at Institut fur Kunststofftechnik of the University of Stuttgart. The topography of the surface was analyzed by a digital light microscopy. Test results on structured acrylonitrile butadiene styrene/polycarbonate (ABS/PC) test panels show, that the examined process parameters melt and mold temperature have a higher influence on the color, gloss and topography than the holding pressure. By increasing the melt and mold temperature, the color, gloss and roughness is significantly influenced. The color difference and gloss decreases with increasing melt temperature, mold temperature and holding pressure, whereas the roughness increases. The melt temperature shows the highest influence on the surface properties. Besides the variation of processing parameters, the structure of the mold surface was modified to adapt the molded surface properties of two different plastic types applying standard injection molding process parameters. Furthermore, the screening of the surface made it possible to detect surface defects in terms of color and gloss and the influences of process parameters on the defects.