Evaluation of distortion and birefringence in plastic molded products.

It is possible to visualize birefringent phase differences (distortion) and the flow direction/stress direction (principal axis orientation)!

Plastic molded products made by injection molding undergo processes such as resin melting, filling into molds, and cooling and holding pressure. If these conditions are not appropriate, internal stresses (residual stresses) may remain, leading to molding defects. A two-dimensional birefringence measurement system can visualize birefringent phase differences (strain) and flow direction/stress direction (principal axis orientation), which are indicators of that stress. As an example, we will introduce a birefringence evaluation comparing polystyrene (PS) molded products under different heating conditions. 【Device Principle】 ■ When light is applied to a transparent body with birefringence, its polarized state changes. ■ By using a birefringence measurement device, it is possible to visualize the polarization information with a dedicated polarization image sensor. ■ By using wavelengths of 523nm, 543nm, and 575nm, birefringence can be evaluated by comparing the polarized states before and after passing through the transparent body. *For more details, please refer to the PDF document or feel free to contact us.