OBSERVATION OF THE POLYMER MELT FLOW IN INJECTION-MOLDING PROCESS USING COINJECTION MOLDING TECHNIQUE

Studies of the polymer melt flow in injection molding process have bee n carried out by co-injection molding technique using alternating sequ ence of transparent and colored PMMA resin. Simulations are also devel oped to predict the melt front advancements for both skin and core mel ts. Fountain flow effect is evident in all case studies. During the pa cking process, the polymer melt flows significantly with the increased packing pressure due to the compressible nature of the melt and the f low concentrates around cavity location near gate area. That the polym er melt flows across the weld line around the gap center in the packin g stage was also observed. Although numerical simulations show fair co nsistence with experimental results in both skin and core material dis tribution, edge effect remains to be taken into account to improve the simulation accuracy.