Shrinkage + warpage predictions

[Anonymous]

I'm running a small part analysis (30grs - 2 cavities) using regular PC from Bayer (Makrolon AL2647).

I want to give an acceptable warpage prediction, using waterline design and pretty much everything the model will have.

I see this material has a shrink rate of ~0.006-0.008in/in, and my question is:

how do I address my warpage prediction, if it is not considering the mold shrink rate. what would it be the considerable % of the warpage that can be considered as shrinkage ont he mold.

I can see that the part max warpage at EOF area is going outboards (out-of-plane) ~1.20mm.

but I would like to know if there is an equation or something that can relate the material shrink rate with the shot size, or part area/volume, etc....

thanks,

[Anonymous]

Hugo,

I have the same issue with Moldflow. Nearly everyone in the industry cuts a tool to a specific shrink value. When visualizing or querying moldflow warpage results I want the option to compare the warped / delfected part back to the original math OR to the "shrunk" math. It is very diffficult to explain to a product engineer that the warp number isn't accurate because it contains the warpage due to shrink, which I have already partially accounted for in the mold.

Moldflow,

Is there something in the works to give this functionality? To echo my earlier point it would be much easier to explain warp results to the lay people if this were implemented. In the mean time, is there a work-around?

Thanks,

Guy

[Anonymous]

For the amorphous materials, the shrinkage depends above all on the thickness, and then on the flow length, the packing ...
The best way to know the real shrinkage would be to make measurements on an existing part having a close design.
I guess you cannot.

So, you can try a simulation on a simple meshed model as a flat plate, with same thickness and same length.
And then, query the parallel and perpendicular shrinkages in the center of the plate.
But, the shrinkage data of the Makrolon AL2647 is only theoretic. It have not been checked by Moldflow.
So the results are not very reliable.
Maybe you could find an equivalent PC with CRIMS.

Anyway, after simulating the warpage on your part, try to find the better average shrinkage with : "results/New custom plot".
Query the result : "Deflection Plot / DEFL W2" and try different general shrinkages values untill the warped mesh fit as well as possible the unwrapped model.

[Anonymous · Accepted solution]

I will second gdlarouc response. THIS SHOULD BE THE NUMBER ONE ENHANCEMENT REQUEST FOR AMI. We all want to model to tool data, that is scaled up model with +shrink. We would want to have moldflow subtract out the mold shrink scaleing or -1.006" scale in this model, the deformation that is left would be the warpage or deviation from part cad data. We have been asking for this for some time.

My only work around involves taking a copy of the origininal model mesh in .stl format, then scale up the model, run it and then export the warped shape in .stl format. I then take the two .stl files and overlay them in Hypermesh to visually see the deformation. Better yet is to get the 3d scanner quality inspection/comparison software that compares scan part data, it turns point clouds of scan into a .stl file, and then compares it to the cad geometry. In this case I use it to compare the two .stl files to show color plot of differences. I have a slide of this in my presentation that I will give at AU 2010. This functionality needs to be in AMI soon.

Don

[madhukeshwart]

Hi,

I was not aware of this optin

Please send me through mail after AU211.