problem with PET preform

[rose1001]

i have some problems with producing PET preforms.
our preforms dont release easily from the mold and it causes lots of waste material.
also preforms dont have good clarity and they seems to be scratched.
what shoud ido to minimize these problems?
thanks in advanced.

[DwightDixon]

Sounds like your mold needs some preventive mantainence from a knowledgeable service.

[rz]

rose1001
your problem maybe originate from your mold,
but using an appropriate mold release agent might minimize your problem.
Coroda's "IncroMax PET 100" can help you by reducing the friction between mold and preform. this can prevent scratching.

[Will Call]

I would follow DwightDixon's advice and have the mold serviced. To run efficiently, you want to eliminate unneeded steps and expenses. Using mold release is usually unnecessary if the molds are built and maintained properly.

[Tom]

Haze in the preforms could indicate that the PET is beginning to crystallize. That might also produce excessive shrinkage and release problems. Crytalization could be due to slow cooling and might also be related to the grade of PET.

Often I find that the melt temperature from the plasticating unit is too hot because the screw is run too fast and the bottle grades are very viscous. The hot melt temperature will keep the preform too hot for too long in the mold, especially the thicker parts. If you see haze in the thicker parts this is your issue. If haze occurs throughout the part then contamination is likely the issue. If on the surface, then it is a release issue.

[Len]

Haze in the preforms could indicate that the PET is beginning to crystallize. That might also produce excessive shrinkage and release problems. Crytalization could be due to slow cooling and might also be related to the grade of PET.

Often I find that the melt temperature from the plasticating unit is too hot because the screw is run too fast and the bottle grades are very viscous. The hot melt temperature will keep the preform too hot for too long in the mold, especially the thicker parts. If you see haze in the thicker parts this is your issue. If haze occurs throughout the part then contamination is likely the issue. If on the surface, then it is a release issue.

Tom's got the handle on this one, I think. Moisture could also contribute to the haze.