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Active Contributor
JayMuller
Posts: 39
Registered: ‎05-07-2013

Re: Shrinkage compensation

03-26-2014 05:21 AM in reply to: nordhb

Hi Berndt,

 

Many thanks for your explanation for the calculation - you should tell your support companies too.

 

I am sorry but the part is still confidential - but it is not expanding and would be an even bigger bug if it would expand with mesh 1 and not with mesh 2.

Then it would be Meshflow not Moldflow anymore. [ And because of that my boss plans to change the sim software into something medieval ]

 

How to corrupt automatic shrinkage compensation:

 

You have a flat part with quite perfect dual domain mesh and an injection coordinate. (single injection)

Try-Out 1: use the node next to your coordinate for injection (maybe max. 2mm away) - mesh 3D and run - and you will get values for asc (auto....) e.g. 0.2 0.35 0.12

Try-Out 2: merge the node next to your coordinate onto the coordinate node (as found in every tutorial) - mesh 3D and run - and now you won't get "real" values..sometimes 0 0 0 or 0 0 0.002

The more nodes by coordinate you enter and merge to, the values go more and more to 0 0 0.

 

Maybe this is also effecting the filling calc, just trying to figure that out...if I know more I tell you.

 

The other bugs: Easy but I can't tell you all but one as example:  Go to Pressure Plot - Properties - Animation (animate result over time) - number of frames (in my case showing 6) and enter 10

Then one popup tells me "enter a value between 1 and 6 " pressing ok, next popup tells me "enter a value between 1 and 300"

 

You can find that in the advanced options and DOE cells too.

 

Regards,

 

JAY

 

 

 

 

 

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Product Support
nordhb
Posts: 480
Registered: ‎03-23-2009

Re: Shrinkage compensation

03-26-2014 06:11 AM in reply to: JayMuller

Hi Jay.

I tested on a plate of 100x40x2 mm, edge length 3mm.

Did according to instructions, to create a node by coordinate 1,1,0 from original in Dual Domain mesh.

Meshed and simulated in 3D, and both Warp deflection shows shrinkage compensation.

See mesh picture:

Plate_100x40x2_mesh.PNG

 

I think the word expansion might mislead a bit here.

Not expanding the mesh as such. It is what deflection plot looks like.

Trying to explain this from a simple shape:

If a U-shaped becoming more Flat _ -shape, it has expanded outwards in that axis, positive as min/max coordinate is larger than original coordinate,
hence no shrinkage compensation, and value would be 0.

Is that explaining it a bit better?

 

Right, see what you say "enter a value between 1 and 300". Will look in to that.

 

Suggest we continue the discussion in thread:

http://forums.autodesk.com/t5/Simulation-Moldflow-Insight/Automatic-shrinkage-compensation-corrupted...

Awaiting your test models in that thread.

 

Thanks.

 

Regards,

Berndt



Berndt Nordh
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Valued Contributor
biricio
Posts: 85
Registered: ‎04-25-2009

Re: Shrinkage compensation

07-18-2014 02:52 AM in reply to: nordhb

Hi, I have this part that has a Moldflow deflection different from the real model (already moulded).
The material is ABS (Chi Mei - Polylac PA-765).
If I make a 'Shrinkage Compensation' with Isotropic about 0.5 % the situation is OK (Moldflow and mouded part are the same)
Why?

 

What is the best approach?
Usually, before moulded the part, in moldflow NEVER active the shrinkage compensation.

If I had done the analysis before moulding the part, the deflection would be different ... and my boss would have fired :-)

 

thanks

 

 

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Active Contributor
JayMuller
Posts: 39
Registered: ‎05-07-2013

Re: Shrinkage compensation

07-18-2014 03:31 AM in reply to: biricio

 

Dear Biricio,

 

just had a look at your attachments - your pdf is very interesting.

 

 

Did I get it right: You have a frame like part with 2 nearly opposite injection (Top and Bottom) locations, which bends the left and right sections both upwards and shows +4 and -4. (???)

 

How lies your anchor plane or better X-axis?

What shrinkage value was added for the tool?

 

Thanks!

 

Regards,

Jay

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