Stress and strain distribution is a common occurrence in Blow moulding technique used for bottle manufacturing. The process involves methods like rapid heating and rapid cooling down of PET material, during which there are chances of acquiring stress on the surface of Preform samples. This can be a result of imbalance between the heating and cooling procedures. The speed of heating and cooling, the time duration all counts in putting up a strain on the sample. Instruments such as Polariscope Strain Viewer, is an ideal set up which used to test and analyze the strain defects in PET preform.

The defects came into the preform are not such which can be visible under human eyes. They may appear normal to you but can lead to drastic results. The stress distribution in preform can be forwarded to the bottle and will generate issues regarding its pressure resistance strength, its standing properties etc. they may get easily cracked on applying a little pressure. Hence, it very important that the bottles manufactured are perfect in sense of strain or stress distribution.

Equipment like a standardized Polariscope, can help in detail inspection of each and kind of stress or strain defects in preforms. It is equipped with two light intensities including monochromatic light and sodium lamp. Allow the user to have a clearer and sharper inspection of preform defects with hi-tech viewing glass. The VIP feature it delivers, is its sample viewing platform which is huge and has angular sample observation system with 45° and 90° angle template on base for preform placement.

The equipment uses refractive index principle for detection of preform strain. The principle says that when light falls on an object and a change in its refractive index occurs, it means there is strain or stress distribution in the specimen. This results in a low quality transparency of the sample. To conduct and analyse the defect pattern seen via Polariscope, one can use our standardized defect chart which is a complimentary offer for our customers.