Optical Sensing of Thermoplastics Solidification in an Injection Molding Machine

摘要

An optical technique for monitoring the solidification of thermoplastics was implemented and studied. A He-Ne laser illuminated the mold cavity through an optical window and a photomultiplier measured the intensity of reflected light during the molding cycle. The light measured is a complex composite of reflection and refraction from crystallites, the mold wall and as many as six interfaces. Polystyrene, polypropylene and high-density polyethylene were used. Further work is required to use this technique for process control purposes.