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how to improve the element matching for 3D part and insert interface

8 REPLIES 8
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Message 1 of 9
ywdmf
1121 Views, 8 Replies

how to improve the element matching for 3D part and insert interface

There are some warnings come out when analysis mobile parts. Pls see below message:

** WARNING 301200 ** 3D Part elements are not matching the overmolded elements
at the overmolded interfaces. Solver convergence may be affected.

** WARNING 301210 ** Nodes from the 3D part or overmolded tetrahedron elements are
either inside its opposing tetrahedron element or a
significant distance from it. The overmolding and part elements
match poorly at the interface.

The warp result is great than actual part. How to solve the poor element matching for 3D Part and insert interface.
So that the convergence and accurate results unlikely. how to improve the element matching for 3D part and insert interface.
pls check the attched.
8 REPLIES 8
Message 2 of 9
sabarinathan
in reply to: ywdmf

Hai ...

If you wants to conduct the overmolding analysis you must match both part and insert element nodes then only u wil get a better results..

Better to match or correct the mesh in fusion or dual domain model after match the part and insert mesh surfaces, u can convert that into 3Dmesh ...

Regards,

Sabari
Message 3 of 9
ywdmf
in reply to: ywdmf

The match between part and insert can be improved by use the the same surface . It is easy for simply part and insert. But it is very diffcult to deal with that for complex parts. Many customers who do mobile meet with such as this problem now. How to solve this problem?

Thanks much!
Message 4 of 9
yannick.moret
in reply to: ywdmf

The solution is to use AMDL. It is specially design to deal with assemblies, and match the mesh at contact interface.
But take care also that your CAD model is properly made, and that there is no interference between your diffeent bodies.

regards
Message 5 of 9

We have worked with lots of insert molding (metal and plastics) parts and tried different ways of solving the interface problem.
Working with the AMDL can work but creates a mesh with extremly many elements (in our case more than 1.6M elements and with AMPI2010 rev 2 I would say at least 2M elements)
This creates high demands on hardware to solve this within resonable calcualtion time (and high risk of running out of RAM)

We also made several tests trying to compare results with warnings and without and when looking on fill pattern, pressure drop and warpage we found that the difference with or without warnings was very small. Only when looking into temperature (in the actual interface) we find significant differences.

Do anybody else got any experience in this matter? Are the warnings really significant for the results or just a mathematical issue?

Cheers
Patrik
Message 6 of 9
BobSherman5561
in reply to: ywdmf

G'day ywdmf (got a name?),

Since we have refused to buy AMDL on principle (it should be a part of Synergy, especially at today's higher price!), I have been quite successful analyzing insert/core deflection analyses in 3D with a careful but tedious modelling process. If you start by modelling the insert at your desired mesh density, and save the DD mesh, and then make the 3D mesh from a copy of this. With the insert DD mesh, delete any elements on surfaces that are not common to the plastic part, i.e. ones that protrude into the mold and are restrained by the mold.

Then mesh the plastic part in its desired density of mesh in a DD mesh and copy it. Delete all of the elements on the common surfaces between the insert and part from the plastic part DD mesh on one of the copies, and then merge with it the partial DD mesh of the insert. Connect up the interfaces between the two meshes, being certain to retain the integrity of the insert mesh so that it will match-up to the insert 3D mesh once you run the analysis. Now you can make another copy of this DD mesh into the 3D plastic part mesh.

I recommend that you keep the DD mesh copies along the way just in case you forget about an insert area, then you don't have to start all over. Believe me, you only make that mistake once! You end up with a lot of interim models if you have more than one insert, but if you do it correctly and the 3D mesh and mesh repair does not alter the surface mesh (with a bunch of what I call "spider webs"), you can then conduct a successful insert and/or core deflection analysis with good results as long as you constrain the part correctly.

Hope this helps,
Bob Sherman, RTP Company
Message 7 of 9

Hello Bob
I must start by saying that its always interesting and stimulating to read hints and tips from someone who knows what they are talking about (unfortunately not always the case on the forum)
I also must say that Im impressed with the patience you must have to model insert molding parts in this way.

We have tried to work this way but found out that with complex geometry it takes us so long time to model the geometry so that it has already changed before we are done with the modeling it self (drawback of working with mobile phones in development phase)

My question to you is if you conducted any studies on the effect of the interface errors?
We did some initial studies on the actual differences in the results with or without errors (i.e. with good mesh and not so good mesh) and we found out that the differences was quite small.
This study was conducted on a fairly easy geometry since we didn't had time to do it on a more complex geometry.

If you have done any studies of this issue it would be most interesting for us to take part of the findings you got from it.

Best regards
Patrik Ingvarsson

Ps Hope to meet you again at the next Moldflow Conference (when ever that will be...) Ds
Message 8 of 9
BobSherman5561
in reply to: ywdmf

G'day Patrik,

No, I am afraid I have not conducted any studies in that regard. The main projects that I have worked on utilizing the 3D insert overmolding analysis have involved one customer and the inserts that were being overmolded were sensitive to movement and stress in the overmolding, so an intact interface and good analysis results were imperative. The procedure I outlined is really basic and doesn't sound too out of the ordinary until you actually start doing the modelling, then you realize attention to details is necessary in order to get the complete compatibility of the insert mesh and plastic part mesh. I was even able to get (unofficially) multiple material inserts to work, but that's a secret procedure I plan to keep to myself for now.

Unfortunately I don't have any "free time" these days to do any studies like that. it's all I can do to keep up with the demands of keeping our customers happy with "normal" analysis results. Besides, my main focus on any studies will likely be in the area of fiber materials and strength analysis when I get some free time.

Good question on when the next User Conference might be, hopefully they will let us know enough in advance that we can plan for it. Thanks for your kind words too.

Bob Sherman,
RTP Company
Message 9 of 9
prabu27
in reply to: sabarinathan

hi sabari,

                      i am prabu from tamilnadu,

 i want to know the procedure of insert over molding in moldflow insight, i know the procedure of two shot injection molding but  i tried the same its not working if you have any pdf of any file which have the procedure please send it to me .my mail id prabupolymer@gmail.com

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