In SOLIDWORKS Plastics there are only three steps required to run a basic filling study: create a mesh, choose a material, and set the gate (injection) location. Today, I am going to focus on a few tricks for setting up gates in SOLIDWORKS Plastics, and explain what may be causing (incorrect) unequal filling in your studies.
The Mesh Matters
If you have any experience in simulation (FEA, CFD, etc.) you already know that what type of mesh you create will drive success of your entire study. In SOLDIWORKS Plastics, this is doubly true, as it not only drives the granularity of the study, but also will have a major impact on your gate settings.
Gate Settings For Shell Meshes
For shell meshes, only set the gate location. Depending on your version, and seat type, you may find you have an option to set the gate size (Pointer Diameter) as well.
However, the injection location, when using a shell mesh, is just a single point. This means that setting the gate size is not taken into account. So the only injection setting needed on a shell study, is the location. (However, if it makes you feel better, you can set this dimension, it just won’t DO anything.)
What Is The Pointer Diameter Used For?
Where the gate diameter (pointer diameter) is important, is with solid (3D) meshes. In this case, the Pointer Diameter will determine how many mesh elements are selected. In a solid mesh study the flow does not begin at a single point, like the shell mesh, but rather, starts at all selected gate elements.
Why Do I Still Have (Incorrect) Unequal Filling?
While the pointer diameter does have an effect in a 3D study, it is ultimately just a mesh selection tool. This means that depending on the amount of mesh refinement in the area of the gate, and the relative size of the gate diameter specified, you may not be selecting the same number of elements in each gate area. The result is an artificially restricted injection location. To illustrate, the part pictured below has two injection locations that are set to have the same gate diameter:
At first glance it may look like everything is OK, but on closer inspection (and with mesh view turned “on”), It is clear that the amount of mesh elements being set as an injection location is very different:
The left side gate selection picked up three elements, while the right side only managed to get one.
What To Do
Now that we see the problem (the area specified for the gate does not select the same amount of mesh elements), there are three basic solutions to the problem.
- Re-mesh the part for higher refinement in the gate area. It may simply be that your mesh is too course in the area you are applying gates. If your mesh is finer, then the gate selection tool will have likely have better results when automatically selecting gate nodes.
- Change the injection location selection tool over to “Injection Location (Face)” and pick roughly the same area of elements for both gates (using the gate diameter as a visual guide).
- Add a small ring using a split line or making a raised gate vestige in the model to represent the gate geometry. Using split lines in a model is fairly common practice when using simulation tools. Breaking up a face allows for more precise application of forces, loads, etc., and SOLIDWORKS Plastics is no different, by splitting the surface or adding a platform, the mesh will be forced to include this geometry. Also, if you want to represent a non-circular gate, this method will allow for any shape you can model. Just remember to use the “Injection Location (face)” to select all the mesh elements that are part of the gate
With these tips, setting up gates will no longer be a “gating” item in your Plastics simulation!