Understanding high rate and high RPM compounding on co-rotating twin-screw extruders

In the polymer compounding industry, corotating, fully intermeshing twin-screw extruders are the primary production units. They range from large, single polymer, high volume lines to multiple unit, quick changeover, small lot production facilities, To keep up with the processor's continual demand for increased economic efficiency, the mechanical design of twin-screw extruders has evolved over 30 plus years to allow transmission of increased power (torque), to an extruder with greater internal free volume, running at higher screw speeds. In order to accomplish each additional increase in power, volume and screw speed, the machine designer has had to overcome many challenges. For example, torque increases are most easily accomplished at the expense of free volume, ie throughput, and screw speed has a negative effect on process melt temperature. Recently, the envelope of high torque, high speed machine design has again been significantly expanded. The impact of these newest developments on compounding technology along with supporting processing examples will be discussed.