The ECO melt filter is based on the long time proven technology of the Ettlinger recycling melt filter ERF. The central element is the rotating cylindrical filter screen, with millions of conical, lasered borings, available in graduated filter fineness. When passed through by the melt, the contaminations are hold back on the surface of the filter drum, the filtered melt flows to the center and is conveyed to downstream equipment of the extrusion line. The filter drum, which is driven by an infinitely adjustable servo motor, takes the contaminations on the surface continuously to a scraper by its slow speed rotation.
At this point the scraper takes off the contaminations and forces them to the discharge shaft, which moves them out of the filter system to the atmosphere. The rotation speed of the shaft is also infinitely adjustable according to the current contamination content. Upon this new discharge shaft design concept, it is possible to process even low viscous materials like PET. As well the flow design of the ECO melt filter was modified. The more equal and smooth flow across the complete width of the filter drum, comparable to a film die, was achieved by a hanger distribution design.
Analog to the advantages of the ERF, also the ECO removes all contaminations with every turn from the filter screen surface. A blinding of the screen by accumulated contaminations, as it happens to conventional screen changers (even with backflush option) and their static screens, is generally prevented. The ECO solves the serious disadvantage of the pressure increase because of the blinding screen by the continuous cleaning of the filter screen surface. This continuity is reflected in the constant pressure of the whole process, at the extruder outlet as well as to the downstream equipment.
The time course and the relation of the melt pressure in front and after the filter screen are important parameters for the control system of the filter system. In case the contamination content is varying, the rotation speed of the filter drum and the discharge shaft, both are adjustable independently, are adapted to the new situation. Because the filter offers a constant open filtration area during production, it works in a process safe and stable condition. Due to this, this filter separates difficult to filter particles like paper and paint but also rubber and silicon or very fine aluminium particles. Thus the ECO melt filter opens new possibilities to increase the use of significant cheaper recycling material or, at least, to replace virgin material at 100%, if the final product allows.