New melt modulation system with multiple control valves was successfully developed to facilitate melt control in cold runner based injection molding. The entire valve mechanism and port geometry were significantly improved. The new valve gave better control characteristic and can be made inexpensively. Valve driving mechanism was also redesigned to be more compact and easy to be installed in a limited mold space. It allows four control valves to be placed in the same mold in which only two original valves were able to fit. The four valve melt modulation performed on a runner system that the effect of melt flow from each valve was influenced by all other valves. The interaction between four valves caused complicated behavior and also a difficulty to establish valve control parameters. A reciprocal search method was utilized and able to determine valve control variables within a reasonable number of trials. Experimentation was done on a potential case study that included both family molding and weld line positioning problems. As a part of the outcome, a simple gain modification was developed and able to find an optimum solution. The technique was carried out in both traditional fixed angle and new developed Bang-Bang control methods. The results shows that melt modulation system with multiple control valves was able to effectively control melt behavior and enhanced filling process.

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