Gate contact diameter of an injection cone

[pk_vel]

Hello all,

Any one can share information about the default gate diamter of the injection cone?

Moldflow help shows the default contact diameter is 2mm for thermolplastics.

Will it get automatically adjusted based on the mesh thickness of the part?

what it says about the upper and lower limits?

Thanks in advance

Regards

PK

[madhukeshwart]

A gate contact diameter is used by the Coupled 3D Flow solver in a Fill or Fill+Pack analysis.

 It is not used with dual domain / midplane mesh.

The Gate contact diameter option assigns a virtual gate diameter to each injection node when a modeled gate or runner system is not provided (direct injection).

This improves the flow front prediction and provides more accurate pressure results and better jetting representation around the gate.

However, where possible, it is advisable to include a modeled gate or runner system.

[JCourter]

Hi PK,

For Midplane and Dual Domain, think about flow as a volumetric flow rate from one node to another.  If you have a runner it is easy to think of the flow going from one node to another down the beam elements.  The flow rate is the same from the injection cone to the part except for compressibility.  Assuming a typical gate, there is only one node connecting the runner system to the part.  All the flow from the runner is going into that one node.  Once in the part, the single gate node is connected to many other nodes so the flow rate drops dramatically in the first nodes away from the part.

If you don't model a runner system, and just have the injection cone on the part, the flow rate into that one node is the total volumetric flow rate you enter into the process settings and the injection cone serves purely as a start point for that flow.

For 3D, the tetra elements for the part, there must be an area for the material to enter the part.  The default gate size is 2mm.  The help documentation is referring to constraints to ensure the assignment of a reasonable gate size provided 2mm is not correct.  That is if the default (2mm) is less than the effective diameter calculated, the effective diameter is used.  By that same understanding, if the default (2mm) is greater than 5D(5 x effective diameter), than 5D is used.  Anything else, the default (2mm) is used.

So your mesh refinement can have an influence on the gate size used because the mesh refinement will dictate the effective diameter calculation.  Now though, it is recommended that a feed system be used.  If not, you can assign a contact diameter rather than using the above calculations by going to Process Settings-->Advanced Options-->Edit Solver Parameters-->Edit Coupled 3D Flow Solver-->Gate Contact Area-->Change to Specified