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machinery feature | Pelletizers

says Crumb. Davis-Standard has developed special location formats to optimize the hole patterns in the die-plate design. The company builds its own die-plates and offers tailored die hole geometries and patterns for different materials, viscosity ranges and applications. The X series new or retrofi t machines with the optimized die-plate pattern are an option for the company’s Universal Pelletor line which is designed to operate as an underwater, water-ring or air-ring system. This design can run with the cutting knife in contact with the die-plate face or in gap mode, depend- ing on the polymer, to greatly improve knife and die-plate life. Davis-Standard is also creating a new hard-face die made to handle highly-fi lled material formulations, targeting compounding applications that generally run at rates under 40,000 lb/ hour (18,000 kg/hour).

Above: Davis-Standard has improved the product throughput of its X series of pelletizers

Right: Davis- Standard’s MicroDie technology for small pellet production is being upgraded

happen often. The new conveyor design provides cooling similar to a quench tank while minimizing operator involvement. This creates an opportunity for one operator to monitor multiple lines. Sluice strand conveyors have previously been available

from Pell-Tec, but only for smaller pelletizing units with working widths of 300 mm.

Pell-Tec also now offers a new FlexSize option on its

strand pelletizers that allows users to vary the length of the pellet produced without exchanging gear wheels. It is particularly aimed at masterbatch projects running 500-600 kg/hour, but it is an option for all pelletizer models. 

Davis-Standard has further improved the capabilities of its X series of pelletizers by offering new and retrofi t debottlenecking kits. These are designed to improve product throughputs of its Universal Pelletor line by up to 25% or more, while maintaining the same equipment footprint and high pellet quality. The die-plate boasts the ‘next generation’ of hole

patterns, says Charles Crumb, business group manager of extrusion pelletizing systems. The size, shape and placement of the die-plate orifi ce holes have been improved, allowing 4 to 5% more holes in a given die-plate. “Hole location must be such that the heel and the

toe of the cutting blade sees exactly the same amount of resin from one end to the other in order to achieve uniform cutting blade and uniform die-plate wear,”

30 COMPOUNDING WORLD | January 2013 In addition, the company’s

MicroDie technology for small pellet production is being upgraded. Crumb says that the new design offers improved cleanability, reduced pressure drop, enhanced geometry, improved insulation and optimised

orientation of the heating media to the orifi ces. Davis-Standard is also improving an option that

doubles the life of the cutting knife assembly. The blade material, blade position, blade geometry and the alignment of the blade to the die face help to extend knife life while trimming maintenance costs and downtime. 

Econ’s newest underwater pelletizing unit, the EUP50, is a lab-scale model built to handle high-performance polymers. It is designed as an alternative to strand units for product development or small batch produc- tion applications, including those involving hard-to- handle materials. The EUP50 has a throughput ranging from 2 kg/h to

100 kg/h, which is relatively low for an underwater pelletizer says Alexander Datzinger, sales manager at the company’s headquarters in Austria. He adds that the unit can handle fi ller loadings up to 80%, which can cause problems with strand pelletizers. Its patented thermally insulated die-plate also helps when process- ing high-performance compounds such as fi lled PEEK, fi lled PTFE or LCP. The die-plate design is the same as that used on

Econ’s larger models. This separates the die-plate from the nozzle to provide thermal insulation and deliver a range of benefi ts. These include quick and easy

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