Optimum design of runner system balancing in injection molding

The runner-system design is of great importance to achieve a successful injection molding process of a family mold with multiple cavities. Using a Galerkin finite element method to simulate the flow of a one-dimensional tube runner-system including phase change in detail we present a power law model. The difference between the pressure and temperature at the gate entrance of all cavities can be taken as the objective function to be minimized because if all cavities are filled simultaneously, these pressure and temperature variations should be a minimum. The purpose is to fill all cavities at the same instant under the same conditions in order to prevent flashing of the mold and to produce parts of improved and uniform quality. In this paper we present a feasible means to optimize the runner design automatically by integrating optimization theory with a flow/thermo-simulation program.