How to use "Cold Runner (3D)" entity type?

[maxmarautodesk]

Dear community,

I am working right now on a simulation including the mold block, single mold insert, two cooling channels, and a part. The feed system of the part is of quite complex shape and contributes to a large amount (>50 %) of the total injected volume. Consequently, I am trying to model the feed system with the quite new entity type "Cold Runner (3D)". My approach is:

1. I am importing the whole assembly from SolidWorks and assign the matching property type to the different CAD bodies.

2. I am assigning the desired mesh densities to the part and the feed system. At the interface of part and feed system, I am choosing exactly the same edge length.

3. I am meshing the part and the feed system selecting the "Precise Match" function for assembly interfaces. This also works to some extend, but not all nodes between the part and the feed system are matched. The nodes merge tolerance is much smaller than the edge length. I also tried chaning the merge tolerance, but it has no effect on the output of the meshing within my investigated range of values. I also measured the resulting mesh and assigned the respective edge length to the relevant edges at the interface between part and feed system, but the mesh does not change. Moreover, it is conspicious that some of the edges to not show the edge length which I gave them with the mesh density tool, but a much larger edge length (compare to attached pictures). However, I cannot see any reason where this could come from...

My questions:
I. Any idea why the software does not match all nodes?

II. How critical is the mesh match between the part and the Cold Runner (3D)? I believe because of the necessary transfer of the plastic flow from one mesh to the other very much?!

III. When does it make sense in your opinion to use the Cold Runner (3D) entity type?

IV. Do I have to mesh the insert together with the part and the feed system or together with the mold block?

I am looking very much forward to your answers! Thank you already in advance!

Background information:

Platform: Windows 7, i7 3.4 GHz, 16 GB RAM

Moldflow: Synergy+Insight 2015

Analysis: Cool(FEM)+Fill+Pack+Warp

Model type: 3D

[maxmarautodesk]

And perhaps somebody (maybe from Autodesk?) can describe the general workflow for using "Cold Runner (3D)" in detail. I just wanted to start a simple fill analysis with the part and the feed system being meshed. However, according to the error message that I get in the analysis log, the two regions are not connected. The polymer can therefore not flow and the analysis was aborted. How do I solve this problem? Or should I say how do I connect the part and the feed system?

[Anonymous]

The runner system must be fully attached to the part (nodes merged).  So meshing them at the same time would be the easiest.  After they are meshed as one body, then select the runner elements and assign them as 3D runner.

It's also possible to mesh the runner as beam elements.  This makes for a significantly smaller element count, but you won't pick up any shear heat at the runner intersections (melt flipper concept).  If it's only a one cavity tool, then beam elements is the why to go.  Although it is recommended to use 3D elements in the gate to better acount for shear in the gate.

I hope this helps,

Tim

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[maxmarautodesk]

Hi Tim,

thank you very much for your feedback and your explanations!

I can see your point. I will try meshing part and feed system at the same time as a single CAD body and then assigning the tetrahedrons of the feed system the "Cold Runner (3D)" property afterwards. However, I see two disadvantages of this method:

• It means more work for me, since I usually have both entities as separate CAD bodies and thus have to merge them.
• Meshing them together as one part will not lead to a sharp interface between the part and the feed system. It is inevitable that some tetrahedrons will contribute to the actual volume of the part and the actual volume of the feed system, if they are located at the transition region. The selection of the tetrahedrons will therefore be not as accurate as

But I think both items are are just minor disadvantages, so I will try to figure out if they are of great influence or negligible.

This leads me to the question: is there any possibility to connect the two CAD bodies or - if separately meshed - the two meshes (besides time-consuming manual merging of layer, nodes, elements, etc.?

Comparing the property dialogs of the type "Part (3D)" and "Cold Runner (3D)" made me realize that there is actually no difference. In both dialogs, the same options are available. This leads me to the question: what is the difference/purpose of "Part (3D)" and "Cold Runner (3D)" elements anyways?

Best regards,
Max

[mtessier]

Hi Max,

A workflow for a sharp interface between 3d hot runner to part is shown here: http://autodesk.typepad.com/beyondmoldflowinsight/2012/07/3d-hotrunner-.html

I'm not sure if it's applicable for 3d cool runner to part, but it's worth a try.

Cheers.

Matt

[maxmarautodesk]

Hi Matt,
thank you very much for the hint about the post in the Moldflow blog. It does seem like a good alternative, and I would like to try it on the Cold Runner (3D) entity type. However, the basic requirement is a good match mesh on both the part and the runner. And that's the point where I am failing. Meshing both parts at the same time, with same mesh density, and precise mesh the software does not give me a matched mesh, meaning that I cannot apply the procedure in the blog. More information about the problem can be found in my other thread:
http://forums.autodesk.com/t5/simulation-moldflow-insight/problems-with-quot-precise-match-quot-whil...


I hope Autodesk will fix this problem soon.

Best regards,
Max

[mtessier]

Hi Max,

Are you able to share an image of the cold runner - part interface?

For geometry like tunnel gates, sometimes you need to be creative, and have the last section of the gate represented on the part geometry to achieve precise match.  Either that or use split surfaces, which is hit or miss.

Good luck.

Matt