Injection Moulding Simulation and Validation of Thin Wall Components for Precision Applications

This paper presents the results of the Moldex3D simulations and experimental validations carried on a complex 3D thin wall part, it critically analyzes the capability of Moldex3D and provides the guideline for more accurate simulation with the commercial softwareMoldex3D. The Boundary Layer Meshing (BLM) mode was adopted in this work to simulate the injection molding process of a hearing aid shell made of Polybutylene Terephthalate (PBT) with 30% glass fiber.

Injection molding experiment was conducted to validate the prediction from Moldex3D. Injection time, injection pressure; pressure loss and warpage were treated as the main comparison criteria. Different parameters setting in Moldex3D were investigated to research their influence on the accuracy of the simulation.

Results showed that the injection molding process prediction from the simulation was relatively precise when the nozzle geometry and the pressure effect on the material viscosity in the simulation model are considered. The determination of a proper heat transfer coefficient (HTC) is also vital for the simulation accuracy.

The agreement between the warpage of the experiment molded parts and simulated parts was not good. Warpage was dominated by the fiber orientation. Predicted warpage was found to be extremely dependent on the filling HTC (Heat Transfer Coefficient) and the fiber orientation model used in Moldex3D, both of which had a significant influence on the fiber orientation.