What to do when simulation need for semi-hot runner system?

[Sanjay_paul]

In autodesk moldflow adviser we can simulate cold runner and hot runner system. But what to do when we have semi hot runner system?

[Sanjay_paul]

Is there anyone who can answer my question?

[bernor_mf]

Hi Paul,
you have a couple of options here, I would say.

You can model a a semi-hotrunner, a combination of hot runners and cold runners.

Then how to mode depends a bit on what your starting point is.
(Single cavity, Multi-cavity , Family mold)

Genererally:
1) You can introduce Floating Plate, between A and B Plate.
This gives a level for hot runner beam.
Creating an injection system for a 3-plate mold

2) If you have the gate location, parting plane and sprue defined, you can actually model the runner system manually
Feed system

3) Importing an existing runner system from iges

Creating runner center lines in CAD. Make sure center lines are broken and intersection points, by break curve or trim curve.

This to give connection of runner in Moldflow Adviser.
Importing an existing runner system

You can change properties afterwards cold <-> hot, dimensions.

Maybe this video will shed some light over your question.
Modeling Runner Systems

Hope this helps.
Regards,
Berndt

[Sanjay_paul]

Hi Berndt,

Thanks for replying. I am aware of these options that you told.

From above picture you can see that some portion it is hot and some portion is cold.If I run the pre analysis check the software shows the following.

so you can not add hot elements to cold.After that you can run the simulation it show nearly same result as cold runner. I will add the SDY file in next reply

[Sanjay_paul]

Here I attached the SDY file. You can see it for yourself.

[bernor_mf]

Hi Paul,

thank you for further details.

As I had a model from you from a previous post I did a quick test:

Changed sprue properties from cold to hot.

The Pre-Analysis check shows ok.

Analysis starts ok.

So it seems to work. 

Regards,

Berndt

[bernor_mf]

Hi again,

will download  585_340_ltr_drawer.zip ‏15327 KB and have a look.

Regards,

Berndt

[bernor_mf]

Hi Paul,

tested both models.

Pre-Analysis check is ok in both studies.

Analysis starts and complete as expected.

Strange you see other message in Pre-Analysis check.

I used:

Release - Autodesk Moldflow Adviser 2016 Service Pack 3
File version - 31.3.804.0
Build - 804_C804L686
Platform - x64

Regards,

Berndt

[Sanjay_paul]

Hi Berndt,

Again thanks for replying. Your software shows ok but I am getting this message. It's a little bit strange. Can you please tell me, is there any difference in the result of these two SDY file on your system? I am using Autodesk Moldflow Adviser 2016 in 64bit platform.

Regards,

Sanjay Paul

[bernor_mf]

Hi Sanjay Paul,

I only see minor differences, see picture.

Regards,

Berndt

[Sanjay_paul]

Hi Berndt,

Hm both results are nearly same. So the hot portion didn't effect too much on result but I think that in real it might have more influence on result. What do you think?

Regards

Sanjay Paul

[bernor_mf]

Hi Sanjay,
well, I am not sure of that the different runner designs in this case has a big difference.

The hot runner holds melt initially.
Runner length about 150mm (without gate beam)
The runner volume is about 6 - 7 cm^3.
The cavity is about 1285 cm^3.
New material from nozzle is quickly replaced in runner.

So similar injection pressure expected on this runner dimension and length, with similar flow rate and injection time.

Further, the melt in cold runner do freeze at mold interface and have a skin and will get a slightly less molten core, but there will also be shear heating.

Part with Cold runner has slightly higher flow front temperature result, indicating a small shear heating, which decrease viscosity, and requiring less pressure to fill.

That is why cold runner design has slightly less injection pressure.

Hence a little difference in injection pressure between the runner designs.

The main required pressure to fill is depending on the part.

Changing process settings will affect the result.
Then need to do new simulations and analyze result.

Regards,

Berndt