Analysis Outline

Purpose and description

When injection molding large products, advantages such as lower injection pressure can be achieved by providing multiple gates. However, injection molding through multiple gates may lead to uneven flow rate and result in poor filling balance. One of the causes for this is inappropriate runner size. This section introduces a comparison of two runner volumes on a multiple gate mold to improve filling balance and reduce injection pressure and associated changes in pressure loss in the runner system.

Filling balance

Explanation: In the model below, flow rates from the gates on both ends with longer runner lengths are significantly lower compared to the flow from the central gate. So the filling rate at both edges falls behind the central part.


Cause and countermeasure

* The analysis model (including the sprue and runner) is created based on 3D CAD data. With the Runner Wizard, sprue/runner models with round cross sections can be easily created allowing for rapid analysis and adjustment.

Results of improved model


Features of improving filling balance

  • Feature 1 Evaluate filling balance for injection molding with multiple gates
  • Feature 2 Achieve uniform flow rate among different gates by adjusting runner diameter
  • Feature 3 Consider possibilities for improved filling balance, reduced injection pressure and even pressure distribution


Associated Case Analysis

Melt front
Resin flow in the mold

Evaluation of weld lines and air-traps


System Requirements