Introduction to Plastic Injection Analyses

An analysis in the Plastic Injection app can include a Fill simulation, a Pack simulation, and a Mold simulation. The simplest analysis includes a Fill simulation only; you can add Mold and Pack simulations for increased accuracy and additional results information.

This page discusses:

Fill Simulations

A Fill simulation predicts how molten polymer material fills the mold cavity. It accounts for heat transfer between the material and mold during filling, and it predicts the changes to viscosity as the material begins to solidify. Results of the Fill simualtion include distributions of pressure and temperature within the cavity and detection of potential short shots and weld lines.

Pack Simulations

A Pack simulation follows the Fill simulation and evaluates the material freezing process in the cavity. During the packing phase, pressure is applied to the injection system to cause additional material to enter the cavity as the part shrinks and freezes. After material flow stops, the cooling phase continues until the part is sufficiently frozen for ejection. Packing results predict the temperature time history at every point of the part, allowing you to evaluate hot spots, gate freeze, and cycle time. Distributions of pressure and shrinkage are also available from the Pack simulation.

Mold Simulations

A Mold simulation predicts the temperature distribution within the mold and cavity and how this temperature changes during the molding cycle. The effects of a mold's cooling system can be investigated, and the process cycle time can be determined. Temperature results from a Mold simulation are used as mold cavity wall conditions in the subsequent Fill and Pack simulations. If you decide to skip the Mold simulation, you can enter uniform temperature values for the mold cavity walls.

Temperature results from the Mold simulation are used as mold cavity wall conditions in the subsequent Fill and Pack simulations, overriding any other temperature data you have specified. If you decide to skip the Mold simulation, mold wall temperatures used in the Fill and Pack simulations are given by any mold wall temperature conditions that you have defined; otherwise, the default mold temperature is used. If you later decide to execute the Mold simulation, you will need to re-execute the Fill and Pack simulations to take advantage of the new Mold simulation temperature results. For more information on how these simulations depend on each other, see About the Mold, Fill, and Pack Steps.

To include a Mold simulation, you must identify at least one coolant part. The mold itself is then represented as a virtual mold which completely surrounds all of the cavity and cooling parts that you identify. For simplicity, mold details such as the parting surface and the ejection system are ignored.