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machinery feature | Pelletizers

designed to make each strand thermally uniform, from surface to centre, for clean cutting. The conditioning system section shrinks the

temperature difference between the skin of the strand and its molten centre, which can be up to 150o

C across

an unconditioned pellet fresh from a water bath or spray nozzles, says Chris Case, vice president, market development. Several commercially installed units are being used

to improve the pelletizing of glass-fi lled PA 66 with black pigment, a common formulation used by the auto industry. The lines are producing temperature-uniform strands, eliminating the shrink voids, angled cuts, jagged edges and fi nes typically generated with strands having a wide skin-to-centre temperature difference. “A good spot for cutting a strand is 10o

Reduction Engineering Scheer’s new conveyor improves the temperature distribution across strands

blades to hold it to the die face but in some applica- tions, linear force from the turning blades actually draws the blades forward.” The design of the EAC brings absolute control of blade position. The PLC allows the user to set the blades adjustment amount and frequency, thereby maintaining an optimal blade-to-die-plate distance dur- ing operation. An optional integrated blade position measuring

system alerts the user when a blade change is required. PLC control also allows a user to move the cutting blades briefl y into contact with the die-face then away as a self-cleaning ‘die-kiss’ step that prevents material build-up. The PLC can store hundreds of recipes. EAC is currently being used on systems processing a

Gala’s EAC

system helps to maximize the

working life of the blade and die face

wide range of materials, including glass-fi lled poly- mers, bio-resins, hot-melt adhesives and high-temper- ature resins, says Roberts. It features a rotational clamp that allows operators to close, clamp and lock with one hand instead of two. Another new product from Gala is the Melt Condi- tioning Device which cuts up the blocks of scrap polymer diverted onto the shop fl oor during process start-up. It has a pneumatically operated cutter blade that is positioned underneath the material diverter valve of an extruder in order to slice the melt blocks into smaller pieces for ease of handling. An operator can set the cutting frequency of the blade. 

Reduction Engineering Scheer reports com- mercial projects for its Flash-off conveyor, a strand pelletizing conditioning system that was introduced in 2011. It features a special temperature compensation section

34 COMPOUNDING WORLD | January 2013

C below the Tg

of the polymer,” explains Case. “At that point the strand has the ability to keep its shape through the cutting process while remaining warm enough to generate the fewest number of fi nes.” Cutter wear may be reduced, as the overall strand

temperature is warm, making it is easier to cut. Processors of the glass-fi lled pigmented polyamide are discovering that reducing fi ne generation, dust and angled cuts in the fi nal product yields a cleaner pelletizing system that runs longer with fewer house- keeping issues. It also reduces the need for a special equipment to separate fi nes, says Case. Friable polymers that offer good clarity, such as PS

or PMMA, could yield an optical defect or chip and break if fi nes or angled cuts appear in the product. The Flash-off system is offered with a water bath or

water tray, with vacuum or blowers, and in lengths of 3, 5 and 7 metres. 

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