Presto’s Polariscope Strain Viewer for Glass and Plastic is used to determine the residual stresses and strain that has an effect on the strength of the product. The device is helpful to determine the actual strength of the glass and plastic that contributes to producing the high-quality products for the end users.
At the time of manufacturing, residual stresses and strains appear that has a significant effect on the strength of the product. The damaging effect may contribute the failure of the product or could be beneficial at the same time. For example, the compressive stresses in the surface layers of toughened glass increases the strength in service.
In the photoelastic technique, polarized light is passed through the products made of transparent glass or plastics to interpret quality and quantity in an optical interference pattern. The residual stress is measured in glass products and strains are measured in plastics moldings, castings or extrusions.