Investigation of in-mold textile injection molding method and development of mold design

Keywords: back of fabric injection, mold design, cooling system design, flow analysis Due to the tight competition environment, increase in production costs, quality and reliability expectations, and cycle times, the desire to improve and combine process steps has become a necessity for plastic manufacturers. In-mold back-of-fabric injection molding systems are one of them. With this system, it is possible to obtain products of the desired quality by providing material saving, low cycle times and minimum scrap rate. With the revision of traditional injection molding techniques, the necessary equipment is provided and the complex production steps are completed at single station and the cost expenses are reduced at high rates. In this study, it is aimed to investigate the differences between in-mold back-of-fabric injection molding method and traditional injection molding method. Advantageously, the differences between the two methods were evaluated in the mold design and flow analysis points of view. The part used for the injection mold design and flow analysis study is the passenger vehicles side door panel covered with fabric structure. The parameters that make up the differences that occur during back of fabric injection molding fabric were discussed in detail. With the optimization of these parameters, the most ideal molding conditions were determined and analyzes and calculations were performed. In addition, the results of the flow analysis were compared with the theoretical results. Since the traditional injection mold design system is not applicable to the fabric structure with the inclusion of the fabric structure in the mold, it is deemed appropriate to apply the mold design approach called reverse injection. As a result of the flow analysis evaluations, it was found that back-of-fabric injection molding showed an increase in injection pressure compared to conventional injection molding, which was caused by the desire to push the polymer melt into the mold wall and to compress the fabric structure into the cavity wall. In addition, there was an increase in the warping values in the back of fabric injection molding method. It was calculated that the theoretical pressure loss was higher. The reason for this is that the analysis piece does not have uniform wall thickness and it has a parabolically progressive piece geometry.