Surface conditions/coatings for PSU?

[ADFToolmaker]

Hi all,

I'm new to this forum. Yes I'm a toolmaker, don't shoot me!

We mould a lot of PSU here, and successfully too I might add, but we have one job that gives us problems, the parts are complex and don't demold well, and stick to the long cores. When we scuff the cores with 1200 paper, no problems, when we polish, the parts stick. I assume we are dealing with a vacuum break problem. Unfortunately the customer requires parts with better clarity than a 1200 finish can provide. Are any of you guys using a coating or surface treatment for molding clear PSU parts?

Thanks in advance,

Andrew

[Suhas]

Hello Andrew,
Thanks for contributing here to the forum. Sorry, I do not have the answer but I have a suggestion. If you know a good thermoset molder of silicones, ask him. He may have the answer. there are a few experienced people here on the forum and I hope they have a better answer.
Regards,
Suahs

[ADFToolmaker]

Thanks Suahas,

We have a silicone moulder in our group, and I make their tools too, but the tecniques we use for part release there such as bead blasting, do not give the clarity we are looking for in the PSU.

[Polyshot]

Hello ADF,
I know you posted a while ago but just in case you're still having an issue or haven't found a good solution yet. You might want to try these:

Check mold for undercuts and/or insufficient draft.
Decrease booster time.
Decrease cylinder and nozzle temperature.
Decrease injection pressure.
Decrease injection-hold.
Decrease mold cavity temperature.
Increase clamp pressure.
Increase mold-close time.
Texturing on part is too deep. The parts may stick in the cavity if a new texture or a retexturing has been performed on the cavity half of the mold.
If possible add undercuts to the core to allow the part to pull out of the cavity.

Hope this can help someone