Three-dimension Numerical Simulation Of Filling Stage In Micro-Injection Molding

With the development of the micro manufacture technique, micro-injection molding technology which has particular superiority is developed and widely used in the micro-mechanical, micro-electronics, biomedical and many other fields now. However, because the size of mold cavity and the volume of micro-plastic parts are very small, the mechanism of micro-injection molding has many differences compared with that of the traditional injection molding. The mechanism and method of traditional injection molding haven't been completely used in micro injection molding.On the base of traditional injection molding numerical simulation, combini ng micro-injection molding theories, considering the microcosmic factors in mic ro-injection molding, ANSYS CFX was adopted to simulate the filling stage in micro-injection molding, which makes up the traditional injection molding sim ulation software in micro injection molding simulation.This paper uses ANSYS CFX to simulate the filling stage of the micro-injection molding process. The work and achievements are as following:1. The effects of wall slip on the filling stage of the micro-injection molding process. Based on the second development for ANSYS CFX, the effects of wall slip on the filling stage of the micro-injection molding process were investigated. The analysis indicate that wall slip promotes the melt flow in the cavity, makes the resistance of melt flow and the pressure of cavity compared with that of the no wall slip condition.With the decrease of cavity size, wall slip effect becomes obviously. In micro-injection molding process, the effect of wall slip is very obvious, and can't been neglected.2. The effects of gravity on the filling stage of the micro-injection molding process. Based on the second development for ANSYS CFX, the effects of gravity on the filling stage of the micro-injection molding process were investigated. The simulation results indicate that gravity influences the filling stage of the injection molding to a certain extent. When the flow direction of melt in the cavity agrees with the direction of the gravity acceleration, gravity promotes the melt flow in the cavity, oppositely, gravity hinders the melt flow in the cavity. In micro-injection molding process, the effects of gravity can't been neglected.3. The effects of viscosity dissipation on the filling stage of the micro-injection molding process were investigated. The simulation results indicate that viscosity dissipation has hardly effect on melt temperature of cavity in micro-injection molding process and can been neglected.4. The influencing roles of melt temperature, mold temperature, injection velocity on filling results in micro-injection molding. Based on the second development for ANSYS CFX, the effects of processing parameters on the filling stage of the micro-injection molding process were investigated. The simulation results indicate that melt temperature, mold temperature have hardly effect on filling rate of mold cavity at very high injection velocity, however, when injection velocity is increasing, the filling rate of mold cavity is obviously increasing; the pressure field has decreasing tendency with melt temperature or mold temperature increasing, however, pressure field increases with the increasing injection velocity.