Vented screws are essentially two screws in one. A vented or two-stage screw is essentially two screws on the same shaft. The first works as a conventional screw by feeding, melting, and conveying the polymer forward. The second screw does the same, except it is melt-fed by the first screw. The first screw operates with no head pressure, while the second has to overcome any head pressure from the die and other downstream components.

Vented Screw Barrels combine the functions of two screws on a single shaft to optimize polymer processing. The initial screw section feeds, melts, and conveys polymer without building head pressure, while the secondary screw receives melt from the first and pushes it through the die and downstream components under pressure. This design allows efficient melting and degassing, improving product quality by reducing volatiles and ensuring consistent extrusion even under varying back pressures.