20% GF PP Warp

[michaelhurley87]

I have had two tools recently come my way that are slatted for 20% GFPP. Looked at Mold Flow, both show warp tendencies and both have been warped. More than MF said but in the areas. I have tried different fill rates, hold times/pressures, water temps, and barrel temps. My conclusion is that the orientation of the fibers is causing the warp. Our corporate team suggested we do tool work to include increasing the gate size from 2mm to 4mm and rad the corners as much as possible. None of this worked either.

Shot neat PP and 20% TF PP... Warp gone. What am I missing?

Both parts are direct drops. The last part is valve gated (3 gates on a rectangle part) and I tried sequencing them to no avail. I am getting very discouraged that this material is kicking my a$$.

Thanks!

[Platt1990]

Just out of curiosity have you tried cure time ?? If so was it a big increase small ??also with pack pressures have you tried more or less?? And how are you filling it d-2 or d-3 what part percentage does each stage transfer at??

[Pilot]

I need a more photos of part with gating. the warpage is due to glass orientation, which (maybe) can be change due to injection cascade stategy …. and materiál press in the area (maybe some area must be without holding pressure (close gate on HP). .. and tool temperature profile...

[michaelhurley87]

This is the bin I had issues with. A change to 20% TF PP solved the issue.

I have adjusted the pack/Hold times and pressures. Cure time... I shaved 10.0s off and added 60.0s. Neither changed the warp whatsoever.

Nothing I changed made this warp any better or worse.

We are running a decoupled 2 setup.

I will post pictures of the seatback shortly.

[Suhas]

First, you are absolutely right on this: 'My conclusion is that the orientation of the fibers is causing the warp.' Fibers orient whereas talc does not since it is a powder.

You may have tried this but the other thing I can think of is to try differential mold temps. The side towards which it is warping should have a lower temp.

Let us know.

Suhas

[michaelhurley87]

I tried up to 45° difference and still nothing. I was not comfortable (nor was I at this point either) running any higher for production. This was just an effort to see if the warp could be changed any.