ON-LINE MONITORING OF POLYMER ORIENTATION DURING INJECTION MOLDING

摘要

A non-invasive, on-line technique for monitoring the orientation of polymer in the mold cavity during injection molding is demonstrated. The propagation velocity of an ultrasonic shear wave can be used to detect anisotropic behavior in the mechanical properties of a solid. Thus, an ultrasonic shear transducer embedded in an injection mold produces a signal that is sensitive to polymer orientation. The technique is shown to be quite sensitive for semicrystalline polymers, but much less effective for amorphous polymers. Sensor results are compared to mechanical tests performed on plastic specimens.