Elementary steps extruders

A more common situation, however, is that before there is any significant frictional heating, an axial position is reached where the barrel is heated to well above the melting point, forcing the creation of a him of melt. In either case, this marks the end of that portion of the process in the extruder called the solids conveying zone, where only solids are present and the only elementary step that occurs is handling of solids. 

We now discuss the elementary steps of processing as they occur in the twin screw segment of the CRNI tangential extruders melt pumping in the single screw segment was covered in Chapter 9. 

Fig. 6.2 Schematic representation of a twin-screw extruder and elementary steps...

Disk extruders. There are several types of screwless extruders. These machines employ a disk or a drum to plasticate, mix, and extrude. Most designs are based on viscous drag flow. They include Maxwell s elastic melt extruder, Westover s stepped disk and drum extruders, and Diskpack [39]. The Diskpack extruder has the capability of performing all the elementary steps of plastics processing by combination of differently shaped rotating... 

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