Injection Molding Weld Line Performance Of The Experimental Study And Numerical Simulation

Injection molding is one of the most important processing methods for producing plastic parts, However, there are still several unresolved problems that confound the overall success of the injection molding process . The forming of weldline wherever polymer flow front meet is one of them. Weldlines form because of the presence of inserts, cores, abrupt change in geometry along the flow path and multiple gates that divide the polymer melt during flow in the mold. It has been observed that the presence of weldlines significantly reduces the mechanical property of injection molded parts . Therefore, in recent years, the analysis on injection molded parts with weldline obtains global concerns, this is. on the one hand , due to large-scale complex parts gradually manifold , on the other hand, the people desires on the appearance and internal performance of parts are increasing high , how to enhance the performance on the weldlind area becomes investigative emphasis . on the basis of the experiments and the numerical simulations , the paper optimized the mechanical property in the weldline area of injection molded parts , the details of paper are as following :(1) Theoretically, I analysed the forming cause. forming mechanism .morphological structure of weldline and its effect on the mechanical property of injection molded parts; discussed the different kinds of factor that affect weldline. such as material, processing condition (melt temperature, mould temperature, injection pressure, packing pressure, packing time, injection speed ), and the measures for enhancing the mechanical property of injection molded parts with weldline;(2) By experiment, that the change of melt temperature affects the Zytel 70G33L parts with weldline and non-weldline has been studied. Experiment shows: along with melt temperature increasing, the tensile strength of parts with weldline and non-weldline both enhance, whereas the stretching strain of ones both fall, on the condition of the parts without weldline, the variance of tensile strength is at a very slow speed, but it is intensify ten times on the parts with weldline, the difference is mostly decided by the fiber orientation structure and the molecular motion.(3) Using Taguchi method ,respectively experimented and the combination of different kinds of processing condition (melt temperature , injection pressure ,packing pressure, injection speed) on Zytel 70G33L and ABS , by analysis of variance, obtained the optimal processing condition combination of parts with weldline and non-weldline , and the affecting level of each factor, found out the one that affect maximally ; simulated the flowing process on ABS by using CAE technology.(4) By experiments, studied that the different flow patters(the inserts in parts have different sizes, namely, the diameters of circular inserts are different and the shape of inserts are circle, square, diamond) of Zytel 70G33L affecting the mechanical property of injection molded parts with weldline. Experiment shows: the samller insert size is, the lighter the damage of weldline is ; on the condition of the diamond insert ,the damage is least; and simulated the melt process of different kinds flowing pattens by using CAE technology .(5) Aiming at Zytel 70G33L and ABS , compared the different effect of weldline on the parts of both at the cold melt and at the hot melto...