Gneuss’ rotary filter makes in-house PE recycling a reality

PE packaging film manufacturer Oldenburg Kunststoff-Technik offers a wide range of high-quality films in different formats. The film waste which occurs during start-up, shut-down and product changes is collected and repelletised in-house on a central recycling extruder equipped with a conventional screen changer – with which it was almost impossible to filter sufficiently. The material recycled on this line could be used for thinner film gauges on the blown film extrusion lines.

If the recycled material is not filtered finely enough, the simple, discontinuous screen changers on the blown film lines would block up quickly. After running trials at several different potential suppliers of melt filtration systems, however, and evaluating the performance of the screen changers as well as the quality of the recycled material, Oldenburg commissioned a Gneuss RSFgenius, with its patented self-cleaning system.

Oldenburg retrofitted a Gneuss RSFgenius 175 to its existing recycling extruder and has thus been able to filter sufficiently fine (75µm) pellets made from scrap to be returned into the blown film extruders rather than being sold. These blown film extruders are equipped with discontinuous screen changers. When using the repelletised material, which has been pre-filtered using the Gneuss RSFgenius, the intervals between changing screens on the discontinuous screen changers on the blown film lines is practically the same as when processing virgin material and the quality of the repelletised material is such that it can be used in place of virgin material.

Due in part to the efficient, self-cleaning system of the RSFgenius 175 on the central recycling line, the filter elements do not require frequent replacement and the quantity of material lost through back-flushing is kept to an absolute minimum.

Oldenburg confirmed that the Gneuss Melt Filtration System has met or exceeded all performance characteristics promised, and that in spite of the tight space requirements on the existing recycling line, Gneuss was able to customise the installation so that it became possible to install it without adjusting the existing equipment.