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SML introduces new PET sheet system

By: Bill Bregar

April 10, 2013

SML Maschinengesellschaft mbH has introduced a sheet extrusion system for thermoforming, called FlexiPET.

FlexiPET allows the production of virgin PET, recycled PET bottle flake, PET film and sheet regrind and other polymers such as polystyrene, high impact polystyrene and polylactic acid.

The machine can process more than 2,200 pounds of PET an hour, at a maximum sheet width of 36 inches and line speeds of up to 230 feet per minute.

SML has opted for a conical twin-screw extruder design, which the company says incorporates advantages the advantages of both co-rotating twin-screw and conventional single-screw extruders. A high-volume feed section can handle even very low-density, recycled material.

Because conical extruders have a short design, melting takes place in the segment on front of the first barrel venting, so residual water has very little time to break down the PET molecule chains. And according to SML, the combination of that feature with a strong vacuum and a second venting section means the PET suffers only a minimal loss of intrinsic viscosity.

The conical design of the screws results in a low-volume pressure section, so the pressure generated is more like that of a single screw than a parallel twin screw, and you can feed the melt directly into a back-flush filter.

The new line is equipped with a new winder combining the advantages of cantilever and shafts, winder carriages and friction winding.

SML is based in Lenzing, Austria.

Tel. 011 43 7672 912-0, email sml@sml.at.