The Melting Process as a Function of Screw Geometry

The melting process for a resin is complex and depends on many parameters, including screw speed, screw geometry, barrel temperatures, and channel pressures. Moreover, the compression ratio and compression rate also affect the pressure in the channel. The melting flux is known to increase with increasing pressure in the channel [1,12]. A series of Maddock solidification experiments were performed at 

Several key observations can be made from studying the photographs in Fig. 6.4. First, the pellets at 5 diameters from the start of the screw are loosely packed in the channel and clearly visible. The pellets upstream of this position would not hold the shape of the channel when the screw was removed from the extruder that is, the pellets fell out of the machine as individual pellets. As the pellets flowed downstream, they were compacted, the entrained air was pushed out through the 

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