Identifying Different Type of Preform Defects with Polariscope

Identifying Different Type of Preform Defects with Polariscope

PET products are safe to pack consumable products which is one of the biggest reasons for their popularity. It is used in different industries like beverages, food, pharmaceutical, consumer items and many other. If manufactured properly, they can maintain the hygiene and freshness of the packed product, be it in any form. Also, air permeability is the matter of concern and need to be checked on that as well.  

PET Preforms
Preforms are the small structures which are blown with hot air to mould them into full-fledged shape. For the quality assessment of preforms, Polariscope strain viewer is used, that highlights the internal defects caused due to external strain. 
To make the best quality preform, the quality is checked at every stage, from identifying the quality of the raw materials to dispatching the consignment. If there are burr and bubbles in the preform, then the final product is definitely going to have defects. This is why it is important to check the defects in preforms before starting the mass productions. 
How to assess the quality of preforms?
The defects of the preforms are too small to be analysed from naked eyes. Use of Polariscope is incorporated to ensure that no defect go unnoticed. The specimen is chosen randomly and analysed under normal light and polarised light. Again, in polarised light, it is observed from two angles and they are 45° and 90°. Assessing the samples helps in highlighting the defects related to colours, transparency, shape and appearance. 
A strain viewer is comprised of incident light and polarized lenses. The light tends to pass in a straight path but if it encounters any defect, it tends to reflect doubly and form birefringence. Every pattern can be related to the preform defect chart. For every type of defect, a recognizable pattern form, matching that pattern with the chart helps in identifying the type of defect.  
Presto is the leading manufacturer and supplier of strain viewer and offers different models to suit the requirements of different industries. Call our experts to pick your suitable model. 

To know more information about its features, price, and technical specifications, give us a call at +91 9210903903 or email us at

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