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Pelletizers | machinery feature

systems for processing bio-based resins, with around 10 lines supplied in the past two years. It is also supplying equipment for the pelletizing of compounds featuring natural reinforcements. These include around 20 lines for processing wood-plastic composites capable of handling filler loadings of 40% or more. Another area of growth is the pelletizing of high-

temperature resins, with “three or four commercial lines” installed over the past two years, including a polysulphone line in the Far East. BKG’s CrystallCut underwater in-line PET crystal- lization system is now being widely used for the production of spherical pellets for PET bottle produc- tion. The single-step technology was introduced eight years ago as an alternative to strand pelletizing. “This shows a change occurring worldwide for PET pelletiz- ing, and it is even being seen in Western Europe,” reports Simon. The spherical pellet yields approximate- ly 8% higher bulk density than conventional shapes. ❙

Coperion has several developments in strand pelletiz- ing underway following its purchase of Pell-Tec in January 2012. The relationship between the two companies goes back to 2002, when Pell-Tec began delivering strand pelletizers to Coperion, says Michael Schuler, Pell-Tec’s CEO. Coperion produces its UG line of underwater

pelletizers at its main facility in Stuttgart, Germany, and will keep the Pell-Tec manufacturing operations in Niedernberg, Germany. Both opera- tions are sharing process know-how and investigating approaches that can support and advance their respective technologies, says Schuler. Pell-Tec is adjusting the through-

put capabilities of its pelletizer line to exactly match the production rates of Coperion’s new MC18 twin-screw compounding extruders. The intention is to offer a complete system including the compounder and pelletizer where the customer does not worry about interfaces or interlinking the controls. Pell-Tec is also developing two

high-throughput strand pelletizing models designed to match Coperion’s ZSK 70, 82 and 92 extruders. The new SP500HD and SP700HD are heavy duty designs featuring working widths of 500 mm and 700 mm respectively.

The SP700HD unit is designed to handle materials with high filler contents. It is offered Pell-Tec’s new SP500HD

strand pelletizer matches up with specific Coperion ZSK extruders

with drive power ranging from 30 to 45 kW delivering the ability to pull 150 strands of 3 mm diameter at rates of 5,600 or 6,300 kg/hour. The SP500HD comes with drive power from 22 to 37 kW and the ability to draw 125 strands at throughputs of 4,500 or 5,000 kg/hour. Like the 700 model, the heavy duty unit has upsized bearings and bearing joints, a more robust cutter and a more rugged puller. In the field of engineering plastics, Pell-Tec’s

customers are moving towards higher loadings of glass fibre in polyamides. Schuler says that compounds with 50-60% glass loadings are being produced to meet demand from the automotive and aircraft industries for parts that withstand heat and dampen vibration. They present pelletizing challenges as they are very stiff, very tough to cut and very abrasive. The heavy duty design of the new SP units has been devel- oped to meet these challenges. The new strand pelletizers will

feature an automated water-assist- ed strand conveyor that catches the strands at the die then guides and supports them to the cutting knife. Instead of a quench tank, the strands are cooled and handled through a combination sluice- and- water- cooled conveying system. The sluice and conveying belt restrands broken polymer

strands automatically. The system is useful in high-throughput operations with many strands, where strand breakage can

January 2013 | COMPOUNDING WORLD 29

The latest strand conveyor from Pell-Tec is designed to overcome strand breakage problems

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