| Abstract | Ultrasonic sensors together with a fast data acquisition system have been used to measure barrel wear, screw wear, screw misalignment, and screw deflection during lowdensity polyethylene as well as high-density polyethylene extrusion on a Werner & Pfleiderer 30 mm twin-screw extruder. The sensors include sol-gel sprayed high temperature (HT) piezoelectric thick ceramic film ultrasonic transducers (UTs), standalone HTUTs, and air-cooled buffer rod type sensors consisting of a room temperature UT and a non-clad or clad buffer rod to which the room temperature UT is attached. The installation and use of these sensors are non-intrusive to the extruder and non-destructive to the polymers being processed. This study has demonstrated the capability of ultrasonic sensors for real-time monitoring of barrel wear and screw status at the pumping, mixing and melting zones of extruders via barrel or flange. The merits and limitations of these sensors are presented. The measurement speed and accuracy are discussed. |
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