EQUIPMENT | MELT FILTERS
Also highlighting a well-established filtration
product, Berhalter points to its Becoscreen continuous melt filtration system. It says the screenchanger is easy to use, features a solid construction and “works absolutely mainte- nance-free, leak-free.” The Becoscreen can be provided with an optional conical insert: instead of the normal cassette, a full-hole cassette is inserted. The conical insert can be unscrewed to enable the extruder screw to be pulled through the screenchanger, which the manufacturer says makes screw changes faster and cleaning easier.
Below: The Erema Laserfil- ter TWIN offers interruption- free screen changeovers and is well suited to recycling applications
Seeking efficiencies According to Nordson, plastics processors are looking for more efficient filtration solutions that allow for finer filtration, greater throughputs, and longer filter life. It offers a variety of filtration media for use with its BKG piston-type melt filters. Aside from solutions such as the BKG FlexDisc, the company also offers candle filters that can be retrofitted into existing systems. It says the candle filter concept combines the advantages of large filtration area with those of proven piston technol- ogy, including lower flux rates, gel filtration, low pressure differential, long filter lifetime, fast exchange of the breaker plate with filter elements, low residence time of the melt in the system, and easy handling. “With our filter candle concept, the available
filtration area can be enlarged by more than 10 times,” says Oliver Brandt, Market Development Manager Recycling at the company. “For example, a BKG Poly melt filter that operates with conventional flat screens has a filtration area of 0.3125m² per piston. The same machine equipped with filter candles has a filtration area of 40m² per piston. Conventional screens need to be changed every three to seven days. Using filter candles extends the filter lifetime to two to four months.” A wide range of accessories enable the filter candles to be used many times over. A pre-heating oven, for example, contains clean breaker plates equipped with filter candles that are instantly available when the filter elements need to be changed. For the cleaning proce- dure itself, Nordson provides BKG pyrolysis cleaning ovens. BKG jet cleaners use heat and vacuum to
56 COMPOUNDING WORLD | July 2021
Nordson says its BKG filter candle packs offer more than 10 times the filtration area of standard filter elements
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remove material such as thermoplastic from the filter candles and other metal parts in what the company describes as an energy-efficient way. In most cases, cleaning cycles take two to four
O
hours. The cleaned parts then need to be put in an ultrasonic bath and afterwards undergo a “Bubble Point Test” to make sure the filter fabric is not damaged. “The cleaning procedure makes it possible to use the filter candles over several years, so that the overall investment cost is relatively low over the lifetime of the filter,” Nordson claims.
Interruption-free A shut-off slider option is available on Erema Laserfilter melt filters (starting with the TWIN model) so the machine can continue in production when one of the screens requires changing. Using a gate valve, an individual Laserfilter unit can be taken out of the production process and put back into operation again after the screen change. During that process, production continues to run via the remaining filter units without any interruption. “This option is particularly important for produc-
tion processes with high throughputs as well as for avoiding interruptions that would lead to a reduction in efficiency due to upstream or down- stream processes (for example, the washing plant beforehand, or the downstream process),” the company says. Laserfilters are intended principally for recycling operations.
Recycling boom Consumer sensitivity to environmental protection and the introduction of laws and regulations related to the circular economy means the plastics recycling market has been booming for some years, according to Fimic. “Many brand owners and the majority of recycling companies need to improve their technology to face the challenges of recycling post-consumer plastics,” says María José Frazzoni, Marketing Manager at the company. “The major quantity of waste plastics is post-consumer, and so very contaminated. To reach high quality
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IMAGE: EREMA
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