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KW Plastics Recycling pushes limits of ERF melt filter

By: Bill Bregar

February 5, 2014

KW Plastics Recycling has become the largest North American customer for the ERF melt filter from Ettlinger Kunststofmaschinen GmbH—running 13 of the ERF250s on recycling lines in Troy, Ala.

The German company set up Ettlinger North America LP in Wheaton, Ill., near Chicago, last year. The North American business started in 2011, but did not have its own facility.

Traditional melt filters push the melt through screens that need to be flushed or changed frequently. The Ettlinger rotational filter is different. On the ERF, after coming out of the extruder, material enters a rotating, drum-shaped filter, which is continuously scraped clean by a knife. That cleans the filter constantly. An auger screw removes unmelted waste such as paper and aluminum.

KW Plastics is a major recycler of post-consumer plastic, including containers from high density polyethylene and polypropylene. CEO Kenny Campbell said the recycling operation is still finding out benefits from the ERF. "We found that our rates improved--better rates, better quality and you waste a lot less material," he said.

"The other thing is, it actually does a better job of filtration, we've found, than the conventional-type screens," he said. The high-quality recycled material goes through a pelletizer.

KW Plastics Recycling runs 26 extrusion lines, including single-screw and twin-screw extruders.

Recycled plastic accounts for nearly 90 percent of the total material KW runs. Ettlinger officials tout the ERF's ability to run heavily contaminated scrap plastic, and remove waste. Campbell said KW does thorough cleaning, washing and drying of its recycled plastic before it gets to the filter.

Campbell said the EFR just works better and more efficiently, with less hassle than traditional screen filters. "There are several advantages to the unit. One is it doesn't require any supervision. Two, the waste purge it generates is only a fraction, as compared to the other screen changers. It just doesn't waste much material at all."

Regular melt filters need backflushing to clean them out. That's not an issue with the ERF.

"One person could easily oversee half a dozen extrusion lines, or more, without any problem," Campbell said.

Initially, Ettlinger North America placed an ERF at KW for a 30-day trial. Campbell said he didn't know if the rotating filter would fit the recycler's needs. The supplier claims the ERF250 can run 4,400 pounds an hour. But Campbell said KW technicians found that number was conservative, and it can run at a much higher rate. The ERF also does a good job on stiffer fractional melt materials that do not flow as well, such as high density polyethylene from blow molded bottles.

And Campbell said the filter gives consistent melt pressure, which is important because KW Plastics Recycling compounds its material before pelletizing.

KW has ordered an ERF500, which links two filter drums in a common base with a single controller—essentially doubling the output of the 250 model. Ettlinger will deliver the 500 to KW in July.

Mike Diletti, managing director of Ettlinger North America, said KW will be the first customer in the United States to get an ERF500. He said KW hopes to get 13,000 to 14,000 an hour on the new filter, versus his current 6,500-7,000 an hour from the ERF250.