Strain and stress assessment is considered to be a vital step in the Plastic Bottle industry. The technique used to manufacture PET bottles, Blow moulding method is a composition of several steps. In which one major step is the rapid heating and cooling of the PET material used for producing a preform. The steps are very sensitive as the imbalance or use of wrong technique while doing this, the preform can generate strain defects on them.


These stress or strain distribution will not be seen with naked human eye but can only be visible using a Polariscope, strain inspection instrument. The Polariscope is used to visualize the stress or strain of preform clearly. Multi-coloured pattern will be displayed under the viewer aperture. To understand the defects better one must use Preform Defect Chart, made as per international strain defect inspection standards.

 The polarized defect chart is useful for checking the strain defects developed in PET preform. It gives you a standard visual assessment. It is suitable for any lab or industry where operators wants to study the stress distribution in Preform structures. The defects underlined in the chart are those which can be detected under natural light and polarised light. In polarised defects further two angular stages are there on at 45 degree and another at 90 degree.


The defect chart is available with deluxe model also as a complementary offer. There are total 12 defects each under all 3 categories with an optimum standard image for reference and the names of the strain defect is also mentioned for further research. The chart has been manufactured under the supervision of industrial experts.