As window profile extrusion moves towards greater use of recyclables and fillers, KraussMaffei Berstorff has responded with coextrusion models where a parallel twin-screw extruder can extrude profiles cores and outer layers with a mix of virgin and recycled resin plus fillers. The recently launched KMD 53 K/P model completes the series of conical twin-screw extruders for the medium output range and extends the wide range of coextrusion solutions, according to the Munich based machinery supplier.
Peter Oswald, director of the Profile Extrusion Product Group at KraussMaffei Berstorff, said the machine combinations in the series are well suited for window profile production based on core technology, layer technology, and combination technology.
KraussMaffei Berstorff noted that processors are increasingly using large quantities of fillers to produce the unseen profile core, which is covered by a thin external layer of new colorfast material. Depending on the individual layers' size, a KraussMaffei Berstorff coextruder can be used both to process the core layer and the top layer.
KraussMaffei Berstorff said its process concept of parallel and conical twin-screw extruders ensures optimum melt homogeneity, while allowing different formulations to be run with just one screw geometry. The company said in a release that it "paid close attention" to the increased requirements for pressure stability of the conical extruders when it designed the conical screws.
The screws are molybdenum-plated and can provide active wear resistance when combined with the deep-nitrided barrels, especially during processing of recyclables and dry blends with high filler proportions. Parallel and conical twin-screw extruders offer modularity, and the conical coextruders are available as a stand-alone version that can be moved in all directions.