Large Diameter Extruder Running PS Resin

2 mm diameter smooth-bore extruder running a PS resin experienced low rates when extruding to a complicated downstream sheet line. The extrudate flowed from the extruder to a screen pack system and then to a sheet die. The line was able to produce acceptable product but at reduced rates. The reduced rates increased the cost of manufacturing the product and caused the plant to miss shipment dates to its customers. At a screw speed of 110 rpm, the rate was measured at 1750 kg/h for a specific rate of 15.9 kg/(h-rpm). Under all processing condi- 

Lead length, flight width, and flight clearance were 203.2, 20, and 0.20 mm, respectively, in all sections of the screw. A 38 mm diameter screw cooling hole was drilled in the shank end of the screw, and it extended 4 diameters into the feed section. The first 2.5 diameters of the screw were inside a water-cooled smooth-bore feed casing. The motor was 450 kW and had a base speed of 1750 rpm. The gearbox reduction was 17.33 1 for a maximum screw speed of 101 rpm at the base motor speed. The motor could be field weakened to provide higher screw speeds. 

First-stage transition First-stage meter 7.37 7.5 4 4.12 and the compression rate was 0.0046 

Lead length, flight width, and flight clearance were 203.2, 20, and 0.20 mm, respectively, in all sections of the screw. A 38 mm diameter screw cooling hole was drilled in the shank end of the  

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