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machinery feature | Pelletizers

alignment of the blades with the die-plate as well as optimizing the pellet flow inside the cutting chamber. These changes help to ensure the production of consist- ent high-quality pellets, says the company. An ergonomic design approach allows for easy

cleaning and quick changes of the die-plate, blade carrier and blades, adds Voemel. The Sphero 50 joins six other models in the Sphero line which deliver throughputs up to 32 tonnes/hour. Automatik, a subsidiary of the gear pump and

filtration system maker Maag (which itself recently became part of Dover Corporation), has also enhanced its Primo line of single-side dry-cut strand pelletizers with its new Primo 200E that features a large cutting width. The cantilever-style model is suitable for the production of thermoplastic compounds, additive masterbatches or colour concentrates at throughputs up to 1.5 tonnes/hour. The model features cutting tool sets for hard,

abrasive, soft or flexible plastics, all of which use a special geometry with a very short unguided length between the feed rolls and the cutters. This enables optimum straight cutting of hard or soft strands. The feed geometry does not subject the strands to pre- tensioning prior to cutting. The ‘low-deposit’ cutting chamber is easy to clean,

and overall retooling time is claimed to be quick and simple. With its 200 mm operating width, the Primo 200E is the largest in the product line which also includes the Primo 60E and 120E. Another recent development from Automatik is its EBG belt conveyor system for pelletizing highly-filled or high-temperature polymers as well as sensitive biopolymers or compounds containing natural fibres. The belt system supports and conveys the material

BPM’s new

XVAK vacuum air knife

system dries 15-25 strands

from the die to the dry cut pelletizer automatically. “We cool the material with air while it is on the belt, then we cut the polymer while it is at 150 to 200o


generating high-quality pellets with no dust, fines or waste,” says Joachim Scheurich, product manager for dry cut systems. Special high-flow air nozzles cool the belt and material from above. A water spray or water bath are also offered as options. Automatik supplies the EBG in two model sizes, the EBG 250 with a maximum throughput of 1 tonne/hour, and the EBG 450 with 2 tonne/hour maximum through- put. Each unit can be ordered with belt lengths of 3, 5 or 7 metres. Automatik has built these special units for about 18 months and there are approximately 30 installations in the field processing glass-filled nylons, WPCs and carbon-filled high-temperature polymers. ❙

Bay Plastics Machinery (BPM) says that it is advancing the control of its strand pelletizing lines, moving from turn-knobs and speed-pots, via closed-loop systems with PLC controllers, through to recent additions to its advanced Digital Pellet Length Control (DPLC) technology. The DPLC system relies on software algorithms and

control of the feed rollers and rotor motors to determine cutter speed. “The PLC adjusts the lower speed roll to maintain pellet length,” says Jason Forgash, executive vice president at BPM. If the extrusion line speed changes, a user enters the desired pellet length through the control panel and the system adjusts the pelletizer accordingly. The company says that the DPLC can deliver material savings by dialling in the process more quickly, and reducing waste of polymers during start-up. The closed-loop DPLC system now has an optional

control feature that measures the pressure of the polymer in the die, then uses that reading to control the operating speed of the pelletizer. Die pressure tracking adjusts the pelletizer speed in real-time. Users requiring pellets of varied lengths can reset the pellet diameter and length mid-process. BPM is now looking to take the control a step further, enhancing the system to allow for a pellet-per-gram spec to be entered, with machinery adjustments executed automatically. In a related development, the company

is working with a customer on the design of a system to read the output of the material feeders to control the extruder. The pelletizer will track the extruder rate and follow it step-for-step. DPLC costs approximately US$2,000 plus the cost of a

dual drive to control the pelletizer, and can control lines with up to 250 strands. Even lines running just five to ten

24 COMPOUNDING WORLD | January 2013

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