Novel design of extension nozzle and its application on real-time injection molding process diagnosed by ultrasound

The multi-stages and narrow processing time window of injection molding process cause its complexity and difficulty for process control and product quality pledge. To explore these physical phenomena of molten polymer at nozzle location during the injection molding process, a T-shape extension nozzle for connecting the barrel and mold was designed in this paper. This T-shape extension nozzle could be easily installed and aligning the injection mechanism in the limited space of fixed plate without further modifying the injection molding machine or mold, and provide the space for installing sensors. It would be a useful diagnosing tool for parameters setting, verification, and stages validation. Two integrated high temperature ultrasonic transducers (HTUTs) were fabricated on both sides of diagnosing zone of T-shape extension nozzle for process monitoring at elevated temperature real-time, non-intrusively and non-destructively. The HTUTs on extension nozzle could be widely applied for diagnosing most of the polymer materials. The progression of the injection molding process, including mold close, injection, packing, screw back, metering and plasticating stages at the nozzle location, was clearly observed by ultrasonic signals. Ultrasonic amplitude and velocity could not only indicate these steps of process, but also correlate to the various injection pressure and flowing state of molten polymer in this paper. Therefore, the designed extension nozzle with HTUTs would provide a novel solution for diagnosis of injection molding process at nozzle location to distinguish the multi-stages of process and detect flowing state of material.