How do I deal with moisture in recycled plastic during extrusion?

Recycled plastic is rarely as clean or as dry as virgin material. It can carry moisture, residues and contaminants that release volatiles when heated. Drying helps, but on many lines it is not enough on its own.

Left in the melt, that moisture and those volatiles lead to bubbles, porosity, odour and inconsistent properties in the finished product. That makes good venting on the extruder more important than ever when you are processing recycled feedstock.

The challenge is that recycled material can be unpredictable. It may foam or swell as it degasses, and that tends to push melt up the vent. Turn the vacuum down to cope and the moisture stays in.

A Screwtech Engineering vent port stuffer lets you keep the vacuum where it needs to be. The self-wiping twin-screw design pushes rising melt back into the barrel while air, moisture and volatiles escape. Precision tolerances allow full vacuum to be drawn.

High quality stainless steel construction suits demanding production environments, and the easy clean two-part vacuum chamber makes cleaning straightforward when the feedstock has been less than kind. An oil filled gearbox with water cooled jacket gives long life at high temperature.

Various sizes are available to suit twin-screw and single-screw extruders. If moisture in recycled material is causing quality headaches, talk to Screwtech Engineering about getting more out of your vents.

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