Rate Increase for an 88.9 mm Diameter Extruder Running a HIPS Resin

The 80 mm diameter screw was built with the channel geometry presented above, and It was Installed and tested. After several days of operation, the performance of the extruder was measured at a rate of 120 kg/h. The predicted performance and the actual performance are summarized In Table 9.3. 

As shown by the data In Table 9.3, the 80 mm diameter designed screw met the target performance and operated at essentially the predicted screw speed. The slightly higher screw speed that was used (58 rpm) was likely a result of the lower compression rate used for the 80 mm screw. The lower compression rate likely reduced the pressure at the entry to the metering section to a value less than 22 MPa. This lower entry pressure would cause the specific rate to decrease slightly and thus require the screw speed to Increase to produce the target rate. 

4 Rate Increase for an 88.9 mm Diameter Extruder Running a HIPS Resin 

A profile extrusion line was required to increase its rate from the current 75 kg/h to about 230 kg/h in order to meet business demand. The extruder was 88.9 mm in diameter and was running a HIPS resin. Operation of the existing extrusion equipment, however, caused the extrudate temperature to be too high at rates higher than about 80 kg/h. The objective of this project was to increase the rate of the profile line from the current 75 kg/h to a maximum rate of 230 kg/h while maintaining the extrudate temperature below 195 °C. 

The profile line runs a blend of virgin HIPS resin (2.1 dg/min at 200 °C and 5.0 kg) and between 0 and 20% of recycle material. The recycle material is from the same extruded parts and thus is composed of the same HIPS resin. The shear viscosity of the resin at 170, 190, and 210 °C is shown in Fig. 9.4. 

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