What is the difference between a vent port stuffer and a side feeder?

They look similar. Both bolt onto the side or top of an extruder barrel and both use a pair of small screws driven by their own gearbox. But they do opposite jobs.

A side feeder is there to get material into the barrel. It pushes fillers, fibres or other additives into the melt part way along the extruder, after the polymer has already been melted.

A vent port stuffer is there to keep material in the barrel while gas gets out. It sits on a vent opening, lets air, moisture and volatiles escape under vacuum, and pushes any melt that tries to rise back down where it belongs.

Screwtech Engineering supplies vent port stuffers with a self-wiping twin-screw design. The intermeshing screws clean each other as they turn, which stops material building up and blocking the vent. Precision tolerances allow full vacuum to be drawn, so degassing works properly.

The units are built in high quality stainless steel for demanding production environments. They have an easy clean two-part vacuum chamber, a separate seal housing and an oil filled gearbox with a water cooled jacket for long life at high temperature.

Alongside vent port stuffers, Screwtech manufactures twin extruder components including screw elements, barrels and liners, shafts and tips, and dies and moulds. If you are not sure which unit your line needs, speak to Screwtech Engineering and they will point you in the right direction.

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