Investigation of the effect of molding variables on sink marks of plastic injection molded parts using taguchi DOE technique

The quality of an injection molded part is affected by material properties, mold geometry, process conditions etc. Obtaining optimum process conditions and mold design is the key problem to improve the part quality. Sink mark is one of several important flaws of injection molded parts. In this article, numerical simulation is combined with Taguchi design-of-experiment (DOE) technique to investigate the influence of process conditions and cavity geometry on sink mark of the injection molded part and optimize process conditions and cavity geometry. An L18(3(7)) orthogonal array based on the Taguchi method was conducted to minimize the sink marks of injection molded parts, and the significance of each factors on sink mark was investigated. For the factors selected in the main experiments, part thickness, holding pressure, melt temperature and mold temperature were found to be the principal factors affecting the sink marks of the injection molded parts.