MACHINERY | MELT FILTRATION


Right: Ettlinger ERF 1000 high- performance melt filter


throughput; first versions are available in sizes suitable for medium-sized recycling lines. The ECO 350, capable of achieving capacities of up to 2,500 kg/h, replaces the old ECO 250, and the ECO 500 (4,000 kg/h) replaces the ECO 250 Twin. The ECO 200 (1,200 kg/h) completes this range. Ettlinger’s melt filter technology is based on the principle of self-cleaning with a continuous flow of melt from the outside to the inside of a rotating, perforated drum. A scraper removes the contami- nants that are held back on the surface and feeds them to the discharge system. As with ERF filters, which are designed for higher contamination, the new ECO filters also have a modular structure, giving users a wide range of options for adjusting the filter properties to the respective task. Uwe Kellner, Managing Director of Ettlinger, says: “PET recyclers are reporting ever-increasing volume flows, resulting in a sharp increase in the capacity utilisation of many machines. At the same time, buyers have more stringent requirements regarding the purity of the recycled material. Consequently, many of the filter systems in operation today are reaching maximum capacity. Our developments have been tailored to these changes in the market. We have achieved en- hanced performance without compromising on filtration efficiency. The new designs combine screen sizes up to 60 µm with a minimum loss of PET through the discharge.” As with other systems, the ECO melt filters are designed to process very low viscosity polymer


feedstock – PA for example, as well as PET. The closed discharge system prevents the occurrence of black specks. For this reason, the classic application for


ECO melt filters is extrusion systems where PET bottle flake is converted into food packag- ing films, packaging tape and fibres, as well as PET repelletis- ing and compounding pro- cesses. ECO melt filters are suitable for single-screw or twin-screw extrusion lines, irrespective of the pelletis- ing system or other down-


stream units, and can achieve throughputs from 150 kg/h up to 4,000 kg/h.


Maag highlights not only the inherent qualities


of its melt filtration system, but the way it fits together with neighbouring components in recycling systems that it also produces. “Spherical, cylindrical, or micropellets – perfect recyclates demand a recycling system in which one plant component meshes smoothly with the next,” it says. “The high-performance melt filters in different sizes cover extreme parameters including high contamination levels of up to 16%, high through- puts of up to 12,000 kg/h, and filtration fineness grades of up to 60 microns,” says Maag. Maag is best known for its melt pumps. A melt pump can be installed at the beginning of the recycling line to ensure precise uniform pressure to balance any in-process fluctuations, thus helping ensure high-quality pellets. The pump also mini- mises loading on the extruder. The precise and stable volume flow rate reduces the extruder’s pressure demand, delivering greater efficiency and extended service life, Maag notes. To protect the melt pump from damage by dirt


Above: The recycling version of Maag’s Extrex6 melt pump (right), with its different tooth configuration, is specially designed for processes involving higher contamination levels and larger particles


20 PLASTICS RECYCLING WORLD | March/April 2022


particles larger than 500 microns in size, the use of a coarse-mesh prefilter is usually recommended. Maag says that in some circumstances, this is now no longer necessary. This is because it now has a version that has been enhanced for processes involving higher contamination levels and larger particles found in recycling operations. “The Extrex6 recycling version looks just like the standard model. The real advance is on the inside, in the gear shafts and bearings,” says Andreas Makert, Manager Business Development Recycling Systems at Maag Germany. The new version of the Extrex6 features special tooth clearances, bigger toothing gaps, and new


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IMAGE: MAAG


IMAGE: MAAG


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