PROCESSING | MELT FILTRATION
Right: Ettlinger says its new ERF350 melt filter provides almost 30% higher throughput than its predecessor, the ERF250
Erema now offers Laserfilter models for PET as well as polyolefin processing
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challenging material to work with due to its narrow process window and a need for a constant, steady flow, which keeps many processers of rPVC from using screen changers or gear pumps at all,” says the company. “The new products eliminate the usual concerns processors have about including screen changers and gear pumps in their process.” PSI’s Expansion Plate Screen Changer (ESC) tolerates tempera- ture swings of more than 8°C. “We solved the chemistry issues relative to heat, flow, and thermal conductivity that make the use of a screen changer with PVC formulations so challenging,” says Don Macna- mara, General Manager at PSI. The screen changer requires only a momentary shut down for a screen change, which PSI says eliminates the need for disassembling the die and the high scrap rates that result from that, especially on short runs. “The screen change process itself is expertly engineered as well, with PLC control of expansion spacer bars that separate the body halves from the slide plate between them,” the company claims. Once the spent screen has been replaced, the spacer bars contract, bringing the steel body halves back tightly against the slide plate, recreating a seal through direct steel-on-steel contact. The ESC comes standard with corrosion-resist- ant stainless-steel components, straight-through chrome plated flow bores to reduce surface friction and eliminate hang-up areas, and identical interchangeable and field repairable upstream and downstream bodies for easy repair or replacement. ADG Solutions has a new model in its CFO line of continu- ous melt filtration systems, the CFO 25. This has a diameter of 25-inches (635mm), allowing throughputs of up to 3,400 kg/h. Aimed squarely at the US market, the CFO 25 has completely imperial sizing. Replacing an existing 24-inch (600mm) model, it is claimed to be fully leak-proof, with the robust design tolerating pressures of up to 3,500 psi.
COMPOUNDING WORLD | July 2018
The CFO unit is fully automatic: when waste builds up and back pressure reaches a pre-set level, a rotating blade sweeps the screen and removes the contamination through a discharge port. The filter can handle a broad range of materials including PE, PP, PS, PC,
and ABS. The design will function with up to 10% paper and other foreign objects up to just under 20 mm in diameter.
Advancements now available
across the complete CFO line include a new scraper design that has been refined for smaller purges. This is said to improve
efficiency and cover a broader range of
applications. The screen plate filter has also been redesigned and is now thicker, harder and presents more uniform hole quality. Later this year, a new diamond-hard plate surface will be available for processing aggressive and abrasive materials. ADG says this will offer a screen life extension of 2-3 times longer than the existing design.
From PO to PET... Erema has been offering its Laserfilter for use in polyolefin recycling systems for more than 20 years. Last year, it launched a modified Laserfilter for PET systems, as well. Robert Obermayr, Head of Erema’s Powerfil Business Unit says it has already sold a number of models in the inline sheet, strapping and pelletising sectors. “The convincing arguments definitely include the smooth handling of PET melts with high degrees of contamination which can also be over one per cent, stable pressure consistency and particularly long screen service life,” he says. “Another benefit of the Laserfilter is that the flow-oriented working principle avoids the formation of ‘black spots’. The user also benefits from the lower melt losses which is achieved thanks to the newly developed discharge unit. Whereas the normal figure for piston filters is 1-2%, with the Laserfilter it is just a fraction of this.”
Obermayr says the Laserfilter is now being used
more and more rather than the piston filter, particularly in the direct processing of PET flakes to make semi-finished or end products. The high process stability, which Erema attributes to its constant-pressure operation, is said to be a key factor in its selection. The company also says that,
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PHOTO: EREMA
PHOTO: ETTLINGER
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