Screw trailing flight

Figure 6.11 Schematics of the solid bed just prior to complete melting (a) the solid bed is pushed to the trailing flight with the Tadmor melting model and barrel rotation physics, and (b) the solid bed is a thin plate and positioned as in the diagram (screw rotation and observation). The cream color represents molten resin...

Figure 6.12 Schematic for the zones of the new melting concept Zone A is the solid bed. Zone B is the melt pool, Zone C is the melt film located between the solid bed and the barrel wall, Zone D is the melt film between the solid bed and the screw root, and Zone E is the melt film between the solid bed and the trailing flight. The cream color represents molten resin...

The cross channel flow is derived in a similar fashion as the down channel flow. This flow is driven by the x-component of the velocity, which creates a shear flow in that direction. However, since the shear flow pumps the material against the trailing flight of the screw channel, it results in a pressure increase that creates a counteracting pressure flow which leads to a net flow of zero1. The flow rate per unit depth at any arbitrary position along the 2-axis can be defined by... 

Once in the melt pool, the fluid particle settles at some position in the channel and commences the circulatory flow alternating between two positions. In the upper portion of the channel, it moves toward the pushing flight and down-channel relatively quickly, whereas in the lower portion of the channel, it moves toward the solid bed (which also slides down channel) or trailing flight (if melting is completed) and down channel relatively slowly. This continues until it leaves the screw channel. 

Leading flight face (leader flight). The forward or front side of the flight of an extruder screw, the rear side being the trailing flight face. 

Trailing Flight Face n (trailing flight) In an extruder screw, the rear side of any flight. The forward side is called the Leading Flight Face. 

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