New Screen Changer Lets Film Processor Ramp Up Scrap Usage

A blown film processor looking to use more production scrap in its process has achieved that objective by switching to a new type of screen changer.

Operating out of three plants in Germany, Oldenburg Kunststoff-Technik GmbH makes a range of PE-based extrusions—air-pillow bubble, stretch and foamed films—on production lines built in-house. Scrap generated during start up, shut down, product changes, etc. is collected and repelletized on a central recycling extruder.

This central recycling extruder was equipped with a conventional screen changer. Over time, Oldenburg realized the screen changer was not filtering the material finely enough. When deployed on its film-extrusion equipment, the repelletized scrap would block the discontinuous screen changer on the line and disrupt production, particularly when Oldenburg was running at thinner gauges. As a result, Oldenburg would typically sell its pelletized scrap rather than reuse it in production.

Over the summer of 2020, after running trials at several different potential suppliers of melt-filtration systems and evaluating both the performance of the screen changers and the quality of the recycled material processed during the trials, Oldenburg decided in favor of the RSFgenius from Gneuss. 

Last fall, Oldenburg  retrofitted the Gneuss RSFgenius 175 to its existing recycling extruder. Since then, it has been able to filter down to 75 µm, enabling pellets made from scrap to be reintroduced into the blown film process at rates up to 100%. What’s more, changing screens on the discontinuous screen changers used on its film-production lines occurs at about the same frequency as when Oldenburg run virgin material.

Introduced at K 2013, the RSFgenius has patented self-cleaning features; the filter elements do not need frequent replacement and the quantity of material lost through back-flushing is kept to an absolute minimum. Michael Oldenburg, director of the company that bears his name, confirmed that the Gneuss Melt Filtration System has met or exceeded all the performance characteristics which were promised in advance. In spite of the tight space requirements on the existing recycling line, Gneuss was able to customize the installation, making it possible to put the screen changer in position without needing to shift existing equipment around.