Pressure Measurement in Molding Process by Ultrasonic Wave

This paper describes the method of measuring cavity pressure during the injection molding process. In this method, a thin metallic foil is placed on the cavity surface. The thickness of the foil is about 80μm and it must be large enough to cover the ultrasonic transducer.From the experimental results, it was clear that the cavity pressure can be obtained by measuring the amplitude of ultrasonic waves reflected at the interface between the mold surface and the metallic foil placed on the mold surface. Moreover, it was clear that the relation between the cavity pressure and the amplitude of ultrasonic wave could be obtained if the roughness and hardness of the contact surfaces were clearly known.