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Quality Parameters for PET Bottles

We all use PET bottle in one way or another. But not many of us know about the hardships involved in getting that one bottle perfect. From its preform to final blow moulded bottle, there is a huge testing process involved. These processes not only help in manufacturing perfect bottles but help a lot in down gauging the size of the bottle while not affecting the quality. In this post, we would try to summarize some of the testing processes of PET bottles. So, here we go…


The rocker bottom of the bottle is the most annoying thing. The main reason behind this is the uneven sectional weight distribution. If analysed aptly, the reason for the rocking bottom is not defective base, if the neck is heavier than the base of the body, it would keep toppling every time you try to make it stand. Sectional weight measurement is done by cutting the bottle into equal sections and weighing them as per the specifications. Hot wire bottle cutter cuts the bottle into sections without any deformity.

Once you get the weight of sections as per the specifications, the next thing is to achieve uniformity in every section. Thickness measurement gauges are used to determine the evenness in the structure of the bottle. Gauges like Magna Mike 8600 has a magnetic probe and a ball to estimate the thickness of the bottle. The probe creates a magnetic field while scanning the body of the bottle. The distance between the ball and bottle is converted into human readable form by the hall effect sensor at the tip of the probe.

After this, even then there is some doubt about the quality of the bottle, a top load tester is employed to check any strained areas in the bottle. This machine applies a load from the top until buckling appears. Buckling is a form of deformity that appears due to external stress. When an external stress is applied, the bottle deforms from the point where there is an internal strain. If the bottle has an air bubble or weak thickness point, the buckling appears on those points. Thus, it helps in determining the defect in the whole production line.



Apart from quality testing, top load tester helps in downgauging a lot. It can estimate the maximum load that a bottle can bear. Proof tests can be conducted to assess the success rate of the downsized bottle when subjected to stacking load.

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