KSB 2000 39g PET bottle deformed 1

[blekiwajt]

Hello all,

Recently ive been asked to investigate why blow-molded PET bottles have deformity ("stomach") on both front sides. Cuted the bottle vertically and horizontally and i can see that thickens is uneven side to side and also from top down(vertically) goes from 0,3 to 1,2mm.
My opinion is that preform heating isnt good but my boss(not engineer but experienced in the field?!) said no way that anything with the preform heating could cause that.

Is there someone with experience on (KRONES)KOSME stretch blow-molding machines or had the same/similar issue?

Thanks,

Cheers!

Miles

 

[patprimmer]

It depends on shape of preform vs shape of bottle, accuracy in moulding the preform, even application of heat before blowing.

You are both probably correct to a point as no process is 100% accurate. If it is just get more precise methods of measurement to find the variations, but how important these variations are relative to each other is the real question.

Regards
Pat
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[blekiwajt]

Well, 39g PCO1881 preform on the 500ml elliptical frontally symmetric and profile asymmetrical bottle - as you can see from attachment.

Basically, bottle shrinks more in the thin areas and leaves thick deformed (stomach) shape in the middle so the label shows bubbles and starts to peel of in because of very big stomach.