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On a twin screw extruder, the vent port is an opening in the barrel where gases are drawn off, normally with a vacuum pump attached. A vent port stuffer sits on that opening and acts as a gatekeeper. Gas goes up and out. Melt gets sent back down.
It does this with a pair of small intermeshing screws, driven by their own gearbox. The screws turn so that their flights convey material downward, towards the main extruder screws. Any polymer that rises into the stuffer is caught and pushed back into the barrel before it can reach the vacuum line.
The clever bit is the self-wiping twin-screw design used in Screwtech Engineering units. Because the two screws intermesh, each one wipes the other clean as it rotates. Material cannot build up and harden on the flights, which is what causes blockages in a plain open vent.
Precision tolerances matter here. The gaps are tight enough that a full vacuum can be pulled through the unit without dragging melt with it. That means moisture and volatiles come out properly, which is the whole point of venting in the first place.
Screwtech builds its vent port stuffers from high quality stainless steel, with a two-part vacuum chamber that is easy to clean and a separate seal housing. The oil filled gearbox has a water cooled jacket so it holds up at the high temperatures found on a compounding or profile line.
The upshot is a vent that does its job without fuss. If your current setup floods, blocks or limits your throughput, talk to Screwtech Engineering about a stuffer sized for your extruder.
For more information on How does a vent port stuffer work on a twin screw extruder? talk to Screwtech Engineering