Energy Transfer Screws for Energy‑Efficient Polymer Extrusion

A new generation of energy-efficient screw designs have been developed, which minimize the melt temperature by mixing the collected melt with the solid particles of the compacted bed . This is accomplished by purposely disrupting the melting mechanism of Fig. 12.3A at some point, by changing the screw geometry to mix the solid with the melt. This transfers thermal energy to the low temperature unmolten solid by conduction of excess energy from the high temperature melt resulting in a lower average temperature above the melting point of the polymer. However, it is not yet homogeneous in temperature and this is accomplished by screw design sections that remix and shear the melt to make it homogeneous in temperature. Screws of this type are generically called “Energy Transfer” screws and are best represented by the ET and Double Wave screw designs.