Modeling a midplane fan gate

A fan gate is a wide edge gate with variable thickness which permits rapid and balanced filling of large parts through a large gate cross-section.

Note: For a Dual Domain or 3D model, it is strongly recommended that you model the gate directly onto the part in the CAD application and import both the part and the gate as one entity into Autodesk Simulation Moldflow Insight. If you already have a Dual Domain mesh, you can model the fan gate by itself in the CAD application, and add it to your existing part. If this is not possible, use the instructions to model a Midplane fan gate.

For a Midplane model, a fan gate can be modeled as an extension of the part. First create the outline of the fan gate by adding new nodes, and then create regions within the gate. The regions are assigned different thicknesses so that the gate has variable thicknesses.

Because of these thickness variations, the easiest way to model a fan gate is to use a 3D mesh. If a 3D mesh cannot be used, thickness changes are best detected when the following conditions exist:

• For a Dual Domain mesh, the thickness to width ratio of the cross section is greater than 4:1.
• For a Midplane mesh, the fan gate is modeled with triangular elements and beams.

  The following diagram shows a fan gate modeled with triangular elements and beams with thickness variations.

  

  The gate land should be modeled with 3 rows of elements, and the center portion of the gate should be the thinnest section. The thicknesses required depend on the size and shape of the gate, the material being molded, and the injection time. When modeling the gate land, it is critical that all existing nodes of the part be used in the definition of the gate, so the gate and part are attached.

Note: A Midplane gate can be added to a Midplane or Dual Domain model, but you will not be able to run Cool or Warp analyses with the Dual Domain analysis because mixed mesh types are not supported on these solvers. If you have to run these analyses, please use the CAD program to model a Dual Domain fan gate.

To model a Midplane Fan Gate:

1. Use the Nodes tools (Geometry tab > Create panel > Nodes) to define the shape of the fan gate.
2. Click (Geometry tab > Create panel > Regions > Region By Nodes).
3. Click on the first node of a region, hold down the control key and select the rest of the nodes forming that region in sequence. In the following diagram, nodes A, B, and C have been selected to form a region.
   
4. Click (Geometry tab > Properties panel > Assign).
5. Click New and select Cold gate surface (midplane) from the drop-down list.
6. Enter an appropriate thickness for the fan gate region in the Thickness text box.
7. Repeat Steps 3-6 for each region in the fan gate, so that the fan gate is thickest at the injection point and thinnest where it joins the part. If additional nodes were created at the gate/part edge, use the stitch tool to connect the gate and the part.
   Tip: You can create curves on the fan gate sides to emphasize their thickness.
8. Click (Mesh tab > Mesh panel > Density) and enter an appropriate mesh density, such that each region in the gate will have at least three rows of triangles.
9. Click (Mesh tab > Mesh panel > Generate Mesh) and click Mesh Now. The option to remesh already meshed parts of the model should not be used to ensure the new regions have the correct density.