Simulating Internal Gas Assist Using SOLIDWORKS Plastics

If you have worked around the injection molding industry long enough, you have probably heard about the process of using gas to fill and pack-out thick-walled plastic parts (also known as internal gas assist injection molding). If you haven’t, you can learn more about it here. Internal gas assist for injection molding (gas assist) can do many great things for the plastic processor: reduce cycle time, decrease tonnage, eliminate sink marks, reduce part weight, and allow for injection molding parts that cannot be created any other way (just to name a few). However, there is a price to pay for these benefits; processing complexity. Fortunately, SOLIDWORKS Plastics can help determine if gas assist is appropriate, as well as help determine the initial processing parameters when setting up a new mold.

So you know you want to run a Gas Assist simulation. That’s great. Now what?

Create Your Mesh

Create Your Mesh

First, create a solid mesh of your part, just like you would for any other solid mesh study. The gas assist functionality is only available for solid mesh studies.

The Gas Assist Functionality Is Only Available For Solid Mesh Studies

Turn On The Gas Assist Functionality

If this is your first time attempting a study of this nature, you will no doubt be looking for the “Gas Assist Analysis” button, and, if you are like me, you will not be able find one. From the code side of things, injecting gas into a mold, is no different than injecting a second plastic into a mold (aka co-injection). Because the code is the same, the button is the same, go to the “Filling Settings” and click the “Co-Injection” option.

Turn On The Gas Assist Functionality

Set The Materials

With the Co-Injection option turned on, you can set the material in the “Polymer” section. Note the drop-down menu next to the button called “Set Co-Injection”.

Set The Materials

The first material will be your plastic, and the second will be your gas for the gas assist. In the default Database under “GAS” you will find “Others/Nitrogen” to use for your gas assist study.

Set The Injection Locations And Material Volume Range

Under the “Injection Location” options, find and set the “Specify Material Volume Range” for each injection location. This setting can be by time or by volume.

Set The Injection Locations And Material Volume Range

Always remember to hit “Add Location” when creating a new injection location, or modifying the injection range of an existing location. If you miss this step, your changes will not be seen in the study.

Once you have these settings, any other modifications to the study are the same as all other plastic studies. If you have finished making modifications, go ahead and run the study!

To view the gas bubble, open the results and select “2nd material Fill time” and then turn on “Isosurface Mode”. Playing the animation or scrolling time back and forth will allow you to watch the gas develop.

2nd Material Fill Time

With these tips, you should be simulating with gas in no time!

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CAPINC was founded on one core principle: Provide the best solutions and services to assist our customers in designing and developing better products. CAPINC provides premier solutions and services in New England to assist our customers in accelerating their design and development process for better mechanical products. Our award winning technical support team is comprised of industry experts with hundreds of years of combined practical experience in mechanical design, design validation and analysis, product data management, and technical communication. We are the award winning 3D solutions partner offering SolidWorks software and training, and the entire Stratasys line of 3D printers and production systems. For more tech tips and blog tutorials check out CAPINC's blog and videos.
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