Characterizing the Impact of D3 on Pressure Prediction

Overview

The D3 variable is used to implement pressure-dependent viscosity into the Cross-WLF viscosity model. Pressure-dependent viscosity can have a severe effect on the pressure required to produce plastic parts when high pressures are required. In order to find the scenarios in which pressure-dependent viscosity can be correctly accounted for, a real-world injection molding process was compared to Moldflow simulations with and without D3, as well as with different meshing techniques.

Objectives

The objective of the project is to determine when the D3 ­variable improves the pressure predictions when used during Moldflow simulations. A secondary goal for this project is to determine what mesh types produced the most accurate pressure predictions during Moldflow simulation when compared to a real injection molding process.

Approach

• Study the fundamentals on Moldflow pressure predictions and the D3 ­variable within the Cross-WLF equation
• Design and develop 3 mold inserts that produce a part at different wall thicknesses
• Determine a material to produce parts on an injection molding machine and simulate in Moldflow
• Gather material from a material supplier too run in the injection molding machine
• Run preliminary Moldflow to ensure the designed parts will produce significant results on the machine and on the injection molding machine
• Test CavityEye hardware and software, the in-cavity pressure data acquisition unit
• Produce steel inserts to be used in the injection molding machine
• Produce parts using the steel inserts and develop a repeatable process that can be transferred to the Moldflow simulations
• Run Moldflow simulations to test both the influence of the D3 and different mesh types to determine the simulations that produce the most accurate pressure predictions

Outcomes

• With this Material, Mold, and Process; Simulations were More Accurate Without D3
• Mesh Technique Matters to Simulation Accuracy More when using D3
• In this Specific Scenario, a Melt Delivery System Meshed with Beams and 3D Meshed Gate and Part is the Most Accurate
• More Testing should be Completed because D3 is Known to Improve Simulations Results in some Scenarios