Influence of rapid mold temperature variation on weld lines strength and appearance of injection-molded parts

In this work an innovative technology for rapid heating and cooling of injection molds has been developed and used to analyze the effect of fast variations of the mold temperature on the improvement of weld lines strength and moldings appearance. The obtained numerical and experimental results show that, by rapidly heating the mold cavity, the polymer melt can develop stronger weld lines. Furthermore, the mold cavity heating combined with the fast cooling of the molded part significantly contributes to contrast the development of surface defects, such as weld lines marks, which are due to stress relaxation.