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DBDennis Bernal06/03/2013

So I have been molding a part for 3 years now in a material made by LG called IF 850. It is a PMMA. Its data sheet is not very extensive but it can be found here:

http://prospector.ides.com/DataView.aspx?I=34&TAB=DV_DS&E=19566&SKEY=34.1230555.59697589%3A2dbb4522-89c0-4e41-9ce1-7c448547653d&CULTURE=en-US

If that link doesn't work, let me know and I can copy paste the relevant info.

For the past 3 years the results I have been getting have been quite bad. The parts work and get me by, but there always seems to be minor issues here and there, like warping, cracking, checmical induced cracking, etc... Due to the geometry I also have to machine quite a bit of the part since one hole is very small and one surface must be perfectly flat. This makes for quite an expensive part. I would like to redesign the part to be 100% moldable. My manager has given me freedom to redesign the part to see if I can make this happen. We will retool for this new design. To prove the new design is better than the old one I purchased Solidworks Plastics. My methodology is as follows:

1. Run the mold flow software with the current material in the current geometry to confirm the software shows similar issues that I am seeing in real life. (Control)

2. Make minor changes in the design to retain the overall look, but improve moldability. See if the changes reduce issues.

I am stuck on step 1. right now. I can't get the current model to run with the current material. The only parameters I have changed is the Specific heat and Thermal conductivity. These are the only things I can find on the LG data sheet that I can then input into the custom material. For the custom material I start off with the "General PMMA" and edit the two paramaters listed above.

If I mesh with a low number of polygons, like 4,000, the system runs. But when I step up to what I would use to run some real analysis, like 400,000 the system gets stuck and says inlet pressure if building and building and building. This is not what happens when I run the 4K sim like above.

Anyways, I know there is a lot here, but any insight would be great.

Thanks.