MELT FILTRATION | MACHINERY
Fine lines: advances in melt filtration
Suppliers of melt filtration systems continue to improve
their offerings to help processors ensure efficient removal of
contaminants at finer levels – and with increasing automation
Recycling – once little more than an afterthought – is now a huge part of the modern plastics industry. A key part of this is filtration, which helps to improve the quality of recyclate – allowing the creation of higher-quality products from recycled material. Erema has developed DischargePro, a control system for its laser filter that improves process stability by reacting automatically to fluctuations during the recycling process. The company says that the system helps to
reduce melt loss by as much as 50%. By adjusting the speed of the scraper disc and the discharge screw according to demand, DischargePro ensures the melt thickens uniformly during filtration. This is a crucial parameter for a consistent and cost- effective process. “The new system automatically determines the optimum process setpoints and ensures that these are maintained during the whole operating period of the laser filter,” said Robert Obermayr, head of the Powerfil business unit at Erema. The discharge control system reacts to specific disruptive factors, including contamination peaks, reduced throughput and increased viscosity. For contamination peaks, it automatically adjusts the speed of the scraper star, returning it to the setpoint speed as soon as the contamination peak
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has been discharged. Regarding reduced through- put, the new filter control system detects significant changes in throughput and adjusts the discharge rate so that thickening remains consistent during filtration. As soon as the melt has a higher viscosity and – as a result – creates a higher pressure drop across the filter screen, DischargePro automatically adjusts the setpoint value to ensure a consistent discharge rate. Longer-term changes are also taken into
consideration because DischargePro takes the ongoing condition of the filter screen into account. Over the course of the screen’s use period, its effective surface area decreases, causing the pressure drop to increase even though the input material is the same. The control system reacts to this by adjusting the setpoint to ensure the optimum thickening ratio is achieved. Another innovation in filtration technology is
Erema’s new 2/406 size of laser filter. Compared to the 2/356 laser filter, it has a 50% larger screen area, enabling much faster filtration of plastic melt.
Fine filtration At NPE, Britas presented its Automatic Belt Melt Filter (ABMF) with two filter heads for powerful, ultra-fine filtration.
Main image: Erema’s 2/406 size of laser filter has a 50% larger screen area than an earlier model, increasing filtration speed
� November/December 2024 | FILM & SHEET EXTRUSION 13
IMAGE: EREMA
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