Three-dimensional transient finite element cooling simulation for injection molding tools

Plastic injection molding is one of the most popular manufacturing processes for mass production, and optimizing the mold cooling system is critical for reducing the cycle time and improving the final part quality. This paper develops a three-dimensional transient cooling simulation model based on the finite element method. Comparing with the conventional cycle-averaged cooling model that uses boundary element method, this method has two major advantages: First, the transient mold temperature is more accurate than the cycle-averaged mold temperature. Second, this method allows performing cooling simulation directly on the real-world mold models without the simplifications that required by the boundary element method. To speed up the transient cooling simulation, this method uses the cycle-averaged cooling model as initial condition and applies the heat flux conservation equations at the discontinuous mesh boundaries to eliminate the interface iterations. It is shown that this method finishes the transient cooling analysis in 478 s on the real-world injection molding mold with more than 6.9 million tetrahedral elements, which is a satisfactory time for practical usages. The simulation result is validated by the actual molding experiment. It is found that the maximum temperature error is less than 4% and the average temperature error is less than 1%. The validation proves the accuracy of this simulation method.