resin time on the barrel

[arturo aguirre]

we are procesing PP Mytex AS95M10 and the remanent time for the resin is 2.06 in the barrel produced by cycle time, i want to know if is to much time for the resin; my main issue with this product is splays or silver marks


I will appreciatte your inputs


regards

[Suhas]

Hi Arturo,
Polypro will not degrade in 2 minutes. I suspect that it may be some additive that is burning if anything is burning but the chances are low. 2 minutes is a low residence time. You must look at your melt temps, injection speeds, gate sizes and so on and also very importantly the venting in the mold. If this is a cold runner mold, make sure all the runners are also vented to the maximum - even if there is some flash in the runners it is fine (not too deep, of course).
Hope this helps,
Suhas

[stewartbf]

Hi,

Suhas is 100% correct. Not sure of the situation of the mold new or old. However if the mold has been running production it needs a good pm. The vents are clogged or dirty. If it has come back from a pm and is doing it on start up then the shop missed cleaning the vents. Seen this before. Worked with a mold that had some weird venting designed into it. So if a different person cleaned the mold the vents would be over looked.

Stew

[tim12871]

I agree with you both! Arturo what is the filler in the PP, glass mineral mica? Is it possible that what you are seeing is degraded material moisture or the filler migrating to the surface.