Description
The most advanced screw design, the barrier screw, is described. Limitations of the metering screw are outlined, emphasizing problems with melting efficiency and pressure surges, the latter causing output instability. An analysis of the barrier screw covers its more complex parameters, with one of its most important features being the good output stability over wide screw speed range. Results of an experiment designed to illustrate the effects of altering major parameters in 5 barrier and 2 conventional screw designs are reported. Virtually all extrusion processes showed gains with the barrier screw.
