PROCESSING | MELT FILTRATION
Right:
Changing filters on BD Plast’s BDOx3 unit during Plast 2018
output rates up to 3,000 kg/h. Filter area is up to 816 cm2
and screens are supplied on 50m rolls,
each sufficient for up to 250 changes. Cofit says the new unit “is the first step towards an Industry 4.0-ready extrusion project” as, through a special remote assistance module, any process failure can be easily assessed and fixed. Control software can also be quickly updated.
Back flush option Also at Plast, Italy’s BD Plast showed its latest continuous screen changer for materials with medium levels of contamination, the BDOx3 BF (the latter initials indicating it is a Back Flush model). It incorporates a novel concept for han- dling flushing that Dante Boicelli, from the com- pany’s commercial department, says is quite different from other machines and which, he claims, has eliminated blockages in the breaker plates. “We have adopted a completely new concept for the construction of the plate holding the filters,” he said. Movements are controlled pneumatically.
Filtration standards The latest melt filter from Ettlinger – part of the growing Maag operation since the beginning of this year – “raises throughput to a whole new level for a global customer base,” according to the company. The ERF350 is a further development on Ettlinger’s ERF250, its most popular model, and was on show at both NPE and Plast. All filters on the ERF350 are self-cleaning via a rotating, perforated drum, through which there is a
continuous flow of melt from the outside to the inside. A scraper removes the contaminants that are held back on the surface and feeds them to the discharge system. This arrangement enables the filter to be used fully automatically and without any production disruptions over a period of weeks and months without having to replace the screen. Advantages are said to include ultra-low melt loss and good mixing and homogenising of the melt. Ettlinger ERF filters are suitable for filtering all
Above: This digital image shows shows how contaminated melt is divided into two channels in the Gorillabelt T melt filter, with a system of levers used to close one channel at a time when pressure sensors indicate that a filtration screen has become clogged. Once the channel is closed, clamps holding the roll-fed screen in place open to allow a new section to be moved into place
36 PIPE & PROFILE EXTRUSION | January/February 2019
standard polyolefins and polystyrenes, as well as numerous engineering plastics such as styrene copolymers, TPE and TPU. Foreign particles can be removed from base materials containing up to 18% contaminants. Depending on the type and level of contamination in the melt and the selected screen size, the ERF350 achieves a maximum throughput of over 3,750 kg/hr. That is around 28% more than the current ERF250 model using the same filtration surface and with the same footprint. The high filtration capabilities of the Ettlinger melt filter design is one of the factors cited by Austrian recycler Candi in its selection of the company’s equipment - an ERF200 model for its plant at Sollenau in Austria and its SC Calex subsidiary at Satu Nou de Jos in Romania. The company reprocesses mostly cosmetics bottles and tubes, dairy and beverage packaging with lid seals, which means it has to deal with silicone and aluminium contaminants at high levels on a continuous basis. “Our customers expect regrind of the highest possible quality from us even though the input material contains extraneous components. We must be capable of removing virtually every single particle of contaminated material,” says Candi Managing Director Gheorghe Campan.
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PHOTO: COFIT
PHOTO: PETER MAPLESTON
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