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machinery feature | Pelletizers

strands can see a return on investment, says BPM. DPLC was conceived as a way to improve the

processing of recycled materials, which tend to be crammed into an extruder due to their low-bulk density. The cramming can cause surging out of the die, which in turn creates processing fluctuations during pelletiz- ing, says Forgash. In addition to low bulk density materials, it can also be used for high-performance polymers, compounds and pigments. BPM has also introduced a new low-cost version of

its vacuum air knife system. The new XVAK series is a low noise pelletizer that controls 15-25 strands. The system effectively dries strands from a water bath or water spray. ❙

BKG has been focusing on the design of more energy efficient pelletizing systems

Berlyn ECM, a supplier of lab-scale and production systems using company-built extruders and underwa- ter or strand pelletizers is adding its first hot-face pelletizer model to its product line. The air-cooled hot-face cutting approach targets processors using material that should not come in contact with water. Polymer is pelletized on the face of a waterless die that is then transferred by air to a cooling table. The hot-face die is offered individually or as part of a system with throughputs from 500 to 6,000 lb/hour (230 to 2,700 kg/hour) says Jay Cassidy, vice president of sales. In 2004, Cassidy and several other partners pur- chased the extrusion and pelletizing product line from Berlyn Extruders, where he worked before the company went out of business. The company offers complete systems including the extruder, screen-changer, continuous filter and pelletizing die, with a choice of water bath/air knife/hot face cutting. Berlyn ECM creates a single, customised control system based on a Eurotherm Maco, Siemens or Allen Bradley platform. Berlyn ECM has developed

a web strand process for a customer that produces 19 strands held together by a web of material stretching from one strand to the next. “They did not want the operator to have to babysit the line, so we created the web strand which eliminates web dropping,” says Cassidy. The trial application was a success. Berlyn ECM can build web stranding systems for customers with projects requiring up to 50 strands. Berlyn ECM is updating its standard die-face plate

technology to a more wear-resistant design. The new die-face plate moves away from a clad face plate configuration, which partially covered the die face, to a solid carbide matrix material that is used across the entire die face. ❙

Bruckmann & Kreyenborg Granuliertechnik (BKG) has focused on delivering energy savings with the develop- ment of its special insulated die-plate design and its rethinking of the water circulation system for its underwater pelletizing systems. Each development aims to deliver energy savings up to 33% compared conventional components, says Ralf Simon, BKG’s managing director. The insulated die-plate is designed to process

high-temperature resins in an underwater pelletizing system where die-plate temperatures often reach 350 to 380o

between 60 to 90o

C, while the water temperature can hover C, explains Simon. In order to

minimize heat loss and maintain good thermal distribution between the die and die face, high-temper- ature steels are used for the die-plate surface and special materials are specified to insulate the hot die body from the cold cutting surface. BKG says that the design reduces the risk of

die-hole freeze-off, which can occur with heat loss and poor temperature distribution. The problem generates increasingly irregular flow in the die as more holes close, while at the same time the die holes that remain open experience higher pressure and varying material flow velocity. This can lead to serious problems for downstream processes, says Simon. With its special systems, BKG says that the hydraulic

pressure used to hold the blades in contact with the die-plate surface is kept as low as possible to reduce wear and energy losses. The company is also optimizing the water filtration

and recirculation system of its underwater pelletizers to reduce energy consumption. “We have eliminated some of the water pumps that we normally install for water filtration, and we have improved the insulation of the system,” says Simon. BKG reports growing sales of underwater pelletizing

26 COMPOUNDING WORLD | January 2013

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