Stretch blow molding preform blues
Stretch blow molding preform blues
(OP)
Hi folks!
I'm running into this problem that I'm having issues wrapping my head around, and I hope that someone will have some ideas to inspire me.
I was wondering if anyone has faced a problem where the preform used in SBM blows up 1/2 way during the stretching/inflation process. Tried reducing the pressure, then it won't blow. Temperature doesn't seem to do much as the preform doesn't want to thin out as it ought to. I think I'm missing something...![[ponder] ponder](https://www.tipmaster.com/images/ponder.gif)
Any ideas/suggestions?
Thanks!
I'm running into this problem that I'm having issues wrapping my head around, and I hope that someone will have some ideas to inspire me.
I was wondering if anyone has faced a problem where the preform used in SBM blows up 1/2 way during the stretching/inflation process. Tried reducing the pressure, then it won't blow. Temperature doesn't seem to do much as the preform doesn't want to thin out as it ought to. I think I'm missing something...
![[ponder] ponder](https://www.tipmaster.com/images/ponder.gif)
Any ideas/suggestions?
Thanks!






RE: Stretch blow molding preform blues
Regards
Pat
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RE: Stretch blow molding preform blues
RE: Stretch blow molding preform blues
Check the grade data for relative viscosity, plasticiser content, nucleating agents and lubricant. You need a blow moulding grade not an injection grade.
One critical data point will be elongation at break. You need a grade that gives it as high as possible.
Another critical point is moisture content. The material must be dry when moulded and I expect the preforms should be dry when stretched. While this is not as critical as it is for polyesters or lower numbered nylons like 6 or 6.6 it still can be a problem if neglected
Regards
Pat
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