warp problem in Autodesk Moldflow adviser.

[klank]

Hi everyone.

I have a question regarding to a warp analysis i have performed with autodesk moldflow adviser.

For the CAD-model i have used in the analysis, i have added 0,55% of shrinkage, as the material to use is Ultramid A3EG6.

when i look at the results of the warp analysis, i would like the original geometry of the part that the analysis is comparing its results to is without these 0,55 % of shrinkage.

in other words, the analysis dimensions is supposed to warp (or shrink) by 0,55%.

so right now, my anlysis is saying that quite much of the geometry is beyond the Nominal max deflection because i have added 0,55 % shrinkage to the CAD-file.

does anyone know how to solve this issue?

BTW.
i am sure that i use the right plastic material, mould and coolant temperature etc etc in the analysis.

 

[patprimmer]

I guess English is not your first language and I am having some problem to understand your post. Also I think apart from language you are missing some points as to the nature of the shrinkage and warpage of your material which according to my information is a 30% glass filled nylon 6.6 from BASF.

To quote 0.55% shrinkage is a dangerous practice with this material if you require accurate prediction of size.

Much more detail is required to predict the shrinkage and warpage and to be frank I have no idea how your software handles the variables so I can't comment on input, but I can comment on what shrinkage to expect.

The material will have considerably different shrinkage according to the direction of flow in the cavity and will shrink a lot more across the flow direction than along it.

The extent of this difference will depend largely on turbulence or lack thereof in the material as it fills the mould.

The extent of the difference will e very dependent on section thickness and if and where that section thickness hanges.

Post moulding shrinkage will be a contributing factor, so it depends on when you measure.

Water absorption after moulding will also have a significant influence. Not only amount of water absorbed, but also over what time and temperature it is absorbed.

Injection speed and hold up pressure will have an influence.

Screw back conditions may have an influence.

Use of regrind or a worn machine or excessive back pressure and screw speed can all damage the glass which influences it's differential shrinkage.

If the language is a problem, I can explain in different terms where you have a problem.

If the concepts are a problem, I can explain reasoning and underlying principles in detail, but I did not want to post a full text book on the subject or go into irrelevant detail or post stuff you already know.

Regards
Pat
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[klank]

Hi Pat.

Thank you very much for your answer

Sorry for my lack of language skills. Danish is my first language.

Anyways, i have meantime found a sollution to my problem.

but thank you once again

 

[btrueblood]

klank,

It's always useful in these threads if the originator of the question gives a glimpse of HOW they solved their problem.