Abstract: A mixing and kneading machine (1) for continual compounding comprises a screw shaft (3) rotating in a casing 2 and simultaneously moving axially translationally. To sustainably enhance the efficiency of the machine as regards its material thruput per unit of time a screw shaft is proposed having the following geometric ratios: Da/Di=1.5 to 2.0, i.e. the ratio of screw shaft outer diameter Da to screw shaft inner diameter Di is 1.5 to 2.0, Da/H=4 to 6, i.e. the ratio of screw shaft outer diameter Da to stroke H is between 4 and 6, T/H=1.3 to 2.5, i.e. the ratio of pitch T to stroke H is between 1.3 and 2.5. The mixing and kneading machine (1) provided with such a screw shaft (3) is operated preferably at a rotational speed exceeding 500 rpm, particularly exceeding 800 rpm.

Abstract: A mixing and kneading machine (1) for continual compounding comprises a screw shaft (3) rotating in a casing 2 and simultaneously moving axially translationally. To sustainably enhance the efficiency of the machine as regards its material thruput per unit of time a screw shaft is proposed having the following geometric ratios: Da/Di=1.5 to 2.0, i.e. the ratio of screw shaft outer diameter Da to screw shaft inner diameter Di is 1.5 to 2.0, Da/H=4 to 6, i.e. the ratio of screw shaft outer diameter Da to stroke H is between 4 and 6, T/H=1.3 to 2.5, i.e. the ratio of pitch T to stroke H is between 1.3 and 2.5. The mixing and kneading machine (1) provided with such a screw shaft (3) is operated preferably at a rotational speed exceeding 500 rpm, particularly exceeding 800 rpm.