Combined Barrier Screws and Grooved Feed Zones

4 Combined Barrier Screws and Grooved Feed Zones 

The development of the grooved feed zone to improve forwarding of plastics pellets and crumb is described in Section 6.2. 

Originally, grooved feeds were used in combination with conventional screws with regard to melting, for low friction and crumb materials such as very high molecular weight polyethylene. 

Melting was achieved by a range of devices which achieved their required function with minimal influence on output rate due to the positive solids conveying. Eventually the barrier screw was substituted for the augmented conventional screw, and the combination of barrier screw and grooved feed zone became established in Europe whereas in North America barrier screws are mainly used with smooth feed zones [13]. 

The combination of barrier screws with grooved feed zones is a further variable which complicates comparisons of barrier screws with conventional screws. Although in 

---