Ettlinger shows off the newest member of the ERF family

Friedrichshafen, Germany — When Ettlinger Kunststoffmaschinen GmbH launched its melt filtration systems in 2003, the idea was to establish a business to serve the emerging recycling market as well as to launch a product family for which demand would be steadier than its other business: very large injection molding machines.

Ettlinger presses are used to mold products weighing up to 100 kilograms — think plastic pallets, fittings or manholes.

Over the years, the two business lines have grown and developed, and Königsbrunn, Germany-based Ettlinger has become a prominent name in advanced melt filtration systems.

The company has continued to refine and improve on the design of its ERF family of melt filters, soon moving away from the traditional static screen filters to the continuous melt filter systems the company sells today. The switch was mainly in response to customer demand: Static screen changers were limited, as sales manager Karsten Bräunig pointed out.

"Feedstocks are often derived from recycled post-consumer waste, and melt filtration systems are used to remove contaminants like paper, aluminum, wood, silicones or high-melting polymer composites from the feedstock. Contaminant levels above 0.5 percent make the process unstable," Bräunig said.

Using a continuous melt filtration system, an open filter surface is always provided, explained Bräunig. Ettlinger's ERF systems therefore have high throughput rates and are able to handle contamination rates up to 18 percent while also conforming with the trend for more automation.

"Also, the residence time of the contaminants in the melt is very short, which improves the quality of the recycled material," Bräunig said.

The ERF systems are basically self-cleaning, consisting of a rotating, perforated drum, through which there is a continuous flow of melt from the outside to the inside. A scraper continuously removes the contaminants that are held back on the surface and feeds them to an exit screw or discharge shaft. This enables the filter to be used fully automatically and without any disruptions over a period of weeks and months without having to replace the screen. The advantages of this design are the constant melt pressure at the filter outlet leading to more reliable processing, ultra-low melt losses and good mixing and homogenizing of the melts.

The company also produces an ECO line, designed for filtering polyolefins, PET, nylon and recycled material containing up to 1.5 percent contaminants, during the extrusion of films, sheet and other semifinished products. It reduces the occurrence of black specks, gels and other impurities.

The ERF family now has four members: the ERF 500, which is capable of throughputs up to a maximum of 6 tons per hour; the ERF 250, with a maximum throughput of 3 tons per hour; the ERF 200, which can process up to 1 ton per hour; and the ERF 350 — the newest addition to the filter family, introduced at Fakuma 2017.

"It is more powerful, but at the same time, very compact," Bräunig pointed out. "Depending on the type and level of contamination in the melt to be cleaned and the selected screen size, the ERF 350 can achieve a maximum throughput of 3.8 tons per hour. At the same time, the very constant pressure means very low melt losses, which is what our customers were asking for."

Also, experience to date has shown that energy consumption is about as low as that of the ERF 250 despite the far better efficiency, "which our customers also like," said Bräunig. "Very much, actually."