Hot Runner for UDEL P1700 Polysulfone

[pjhall]

I'm working on the mold design for a new project. The part is a cylinder shaped part with a hydraulic core pull. The material is UDEL P1700 Polysulfone (4 different colors). This will be a high volume runner, so we want to use a hot runner. Encoe China is telling me that they do not recommend gating directly with polysulfone and want to gate into a sub runner and tab gate the part. This will not work due to the high volume. Does anyone have experience using hot runners running polysulfone? I have a call into Encoe US, but am waiting to hear back.

Thanks,

P.J.

[Suhas]

PJ,
What is their reasoning for the subrunner and tabgate?
Suhas

[pjhall]

After much research with both Solvay and Encoe it seems that polysulfone and direct gate hot runners do not get along. It shears to much going through the flutes of the tip (diverted, triverte, or quadverted). Solvay suggests gating into a sub runner with a drop where the material flows around the tip instead of through it. I ended up switching to 2 sprue drops gating into 2 sub runners.