Poor Barrel Zone Temperature Control

2 mm diameter plasticating extruder was running GPPS resin and discharging to a specialty downstream process. Like most processes, the downstream equipment required a nearly steady supply of molten polymer. For this case, the 

In order to reduce the cooling level to the barrel zone, a metering valve was placed in the water line upstream of the solenoid valve as shown in Fig. 12.8(b). Now when the controller opens the solenoid valve, a much lower quantity of water and thus cooling is available to the barrel zone. Prior to this modification, the barrel temperatures oscillated 10 °C about the set point temperature. After the modification, the temperature oscillations were reduced to about 3 °C, and the profitability of the process was improved due to the minimization of resin consumption. 

2 Optimization of Barrei Temperatures for improved Soiids Conveying 

An extrusion trial was performed at the processor s plant using a 38.1 mm diameter production extruder, a proprietary screw design, and resin that had previously exhibited flow surging and reduced rate. The extruder was equipped with three barrel zone heaters with control thermocouples (labeled Tl, T2, and T3) and two pressure sensors. One pressure sensor was located in the midsection (zone 2) of the barrel (P2) and the other at the end of the barrel near the tip of the screw (P3). Both transducers were positioned over the top of the screw such that a pressure variation due to screw rotation would be observed. 

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