Stress and Strain distribution is a common phenomenon experienced by bottle preforms while manufacturing process. The process of blow moulding includes the blowing, heating and rapid cooling of material. Slight changes in the process of cooling and heating can effect badly in material distribution. And this is the moment when strain is distributed at corners or any particular point.

This can lead to uneven bottle surface, misbalancing of the bottle, disturbance in the filling line if the bottle falls down. Cracking or bursting of the bottle under exterior pressure. To avoid the situations one must invest in core quality inspection for detecting strains in the preform surface. This can be conducted using a Polariscope strain viewer.

This equipment is considered to be an ideal setup for detecting the stress or strain on plastic preform surface. The Strain build up can only be detected using the principle of photoelasticity which says that a light beam will change its path of refractive index if the surface has generated any stress or strain.

The equipment has a large viewing are with engraved area for placing the preform sample. Two angle wise engrave are there, one at 90 degree and other at 45 degree which is known to be a standard template for precise strain analysis. Equipped with monochromatic light and sodium light sources for inspection of a wide range of flaw. The patterns in form of colored pictorials can be easily seen and compared with the Preform defect chart.