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klp2kor
Posts: 24
Registered: ‎12-29-2009
Accepted Solution

Negative volumetric shrinkage

229 Views, 1 Replies
01-16-2014 04:52 AM

Hello,

 

Can someone explain the consequenses of negative volumetric shrinkage ??? how critical is it ? what value is allowed ?

How to solve it when it is near the gate and away from the gate ??


regards,

klp

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nordhb
Posts: 480
Registered: ‎03-23-2009

Re: Negative volumetric shrinkage

01-17-2014 01:16 AM in reply to: klp2kor

Hi,

negative volumetric values indicate expansion rather than shrinkage.

Basically, volumetric shrinkage is needed to get the part out of the mold.
The negative volumetric shrinkage indicating material expansion,is due to overpacking of material
and area of part can get stuck in mold, causing part quality issues when open mold and ejecting part.
Avoid negative shrinkage on ribs, as this can cause ejection problems.

Volumetric shrinkage can be controlled by the use of packing profiles.
Packing pressure level by time, and decay as needed, to control the volumetric shrinkage.

Help on:
Average volumetric shrinkage result :
http://help.autodesk.com/view/MFIA/2014/ENU/?url=/cloudhelp/2014/ENU/MoldflowInsight/files/GUID-C9C9... 
Packing profiles
http://help.autodesk.com/view/MFIA/2014/ENU/?url=http://help.autodesk.com/cloudhelp/2014/ENU/Moldflo... 

Another post:
http://forums.autodesk.com/t5/Simulation-Moldflow-Insight/Negative-value-for-Volumetric-Shrinkage/td... 

Hope this helps.

Regards,
Berndt



Berndt Nordh
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