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Imbalance in multi cavity

5 REPLIES 5
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Message 1 of 6
rajeshkumarpv
735 Views, 5 Replies

Imbalance in multi cavity

Hi,

 

When using multi cavity analysis we found imbalance in filling with following cases

 

  1. Case 1-Full 3D directly meshed all surfaces
  2. Case 2- Single cavity meshed and rotated to replicate
  3. Case 3- Part 3D & Feed Beam elements
  4. Case 4-Full 3D Direct cone eliminating sprue
  5. Case 5- Part,Runner & gate 3D, Sprue- Beam elements

attached the pictures for reference. Looking for your comments on the elements type for Part and feed for multi cavity considering 3D.

Version used 2015

 

Thanks in advance.

 

Regards,

Rajesh PV

5 REPLIES 5
Message 2 of 6

I am sure you might be expecting similar end of fill regions in all the options but visually all are different. 

 

Case 1-Full 3D directly meshed all surfaces- 

Case 2- Single cavity meshed and rotated to replicate

 

case1&2.png

 

Both Case  -1 and 2 are correct. Even thought Geometrically balanced, there may shear induced imbalance. Actually result may be as actual. 

refer below shown example, high sheared material will be hotter compared to low sheared material. 

 

Full 3D will capture development of Non Homogeneous melt conditions. Some cavity receives hotter material & other may receive colder material.

 

shear induced imbalnce..png

 


Case 3- Part 3D & Feed Beam elements.

case3.png

This option shows, similar temperature, pressure in all the cavities but not as actual 


Case 4-Full 3D Direct cone eliminating sprue

case4.png

it is not advisable option, can be used during initial iterations.


Case 5- Part,Runner & gate 3D, Sprue- Beam elements

This option also can be used, but your results shows, there is shoot up in pressure due to imbalance in results.

case5.png

 

Case 1, 2, 3, 5, you can expect similar results, but need to care in meshing of gates,Gate region &

there must  be clear boundary between gate and part also finer mesh around gate.

(refer below Tips provided by Autodesk), which may be helpful to you.

 

caring for 3 d -gate meshing.png

 

 

 

TIPS 2: 

3d gate -tip2.png

 

 

Madhukeshwar Talwar

FORD MOTORS PRIVATE LIMITED, Chennai
mail: madhukeshwart@gmail.com
09600060862
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Message 3 of 6

Hello Madhu,

 

With full 3D gate multicavity runner systems we are facing this problem many times, even though we couldn't find any impact in melt internal behaviour due to shear heating (Shear induced flow), we could see perfect concentric flow with homogeneous melt conditions still the flow imbalance is coming. Do we need to change the runner design in that case if flow imbalance happening not due to non-homogeneous melt conditions..?

 

Regards
Sabarinathan. S
Core Engineering Specialist - Plastic, Auburn HIlls, USA
eMail : sabi1021@gmail.com
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Message 4 of 6

Dear Madhu,

 

Thanks for the detailed information.However there is huge variations observed with these types of mesh variation. Also the 3D repair wizard creates variation across cavities which can  also induce variation. Was much interested in looking for some advice to over come during the mesh wizard.

 

Thanks again for providing the information which is greatly useful.

 

Regards,

Rajesh PV

Message 5 of 6
mppkumar
in reply to: rajeshkumarpv

Hi Rajesh

 

what is the number of layers through thickness, you have kept while converting to 3D.

 

if you have 6 layers across thickness, please try same set of analysis with 8 or 10 layers and share the results.

 

Thanks

Pradeep kumar

Thanks
M P Pradeep Kumar


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Message 6 of 6
rajeshkumarpv
in reply to: mppkumar

Hi Pradeep,

 

This mesh was used with 8 layers across thickness.

 

Regards,

Rajesh PV

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