machinery | Pelletisers
Right: Maag’s PEARLOflex underwater pelletiser is designed to manufacture spherical pellets in
compound and masterbatch applications
The company’s DROPPO drop pelletising system is designed to produce uniform dust-free spherical pellets. It is ideally suited for low viscosity melts and liquids with viscosities less than 500 mPas, as well as for filled materials based on such carriers. Cooling and solidification may use air, nitrogen or water. A number of other new pelletising
initiatives have emerged from the combina- tion in 2015 of the pelletising expertise of Maag Automatik, Gala and RE Scheer with the pump and filtration knowledge of Maag. The Maag PEARLOflex underwater pelletiser, for instance, has been developed to manufacture spherical pellets of compounds, masterbatches, blends and recyclates. The company says that it is compatible with a wide range of polymers and thermoplastics, including, but not limited to, polyolefins (LDPE, HDPE, PP), styrene polymers (PS, SAN, ABS), polyacetals (POM), polyesters (PET, PBT, PEN), polycarbonates (PC), polyurethanes (TPU), hot-melt adhesives, rubber, and natural and synthetic resins, and can reach production rates of up to 500 kg (1,100 lbs) per hour. In the PEARLOflex system, plastic melt is trans-
Below: Maag’s OTP technology is said to be particularly appropriate for production of optical quality polymers
ferred to the die plate via a hydraulically operated start-up valve. From the die plate, the heated melt is extruded through holes oriented in a ring shape into the cutting chamber, which is flooded with process water. The cutter head then cuts the polymer into pellets, which are sent to the dryer via the process water piping. In the dryer, pellets are separated from the process water and moved on for further processing while the process water is filtered, tempered and returned to the cutting chamber. All key components are integrated into a compact,
single base frame that employs a modular design that includes a lift-and-remove dryer housing. The system also offers a turbine-style cutter hub and cutter with a single-sided long blade, including automated or manual blade-advance capabilities. The narrow face die plate design allows minimum thermal exposure. The system
is top-mounted for the diverter valve, die plate, water box and pelletiser and can be upgraded with additional top mounted and hinged modules for the melt pump and melt filtration. Maag Automatik’s Optimised Temperature Pelletising
(OTP) enables pelletising of technical thermoplastics for the most demanding applications in Maag’s underwater systems. The OTP system uses a two-stage cooling approach. In the first stage, pellets are cut in pressur- ised overheated water at a temperature of greater than 100°C. Pellets are then transferred and separated from the overheated water before being passed to the second cooling circuit, where the temperature is less than 95°C. After cooling, the pressure is released and the pellets are separated by a centrifugal dryer from process water before subsequent processing or packing. The closed loop operation eliminates the risk of
contamination while the production of spherical pellets minimises the risk of dust – spherical pellets are said to result in lower levels of dust generation during transportation. The company says OTP pellets meet the high standards required for production of medical and optical parts such as ophthalmic lenses and automotive panorama roof panels. Another Maag development is the PURO tempered
process water system, available as an integral component for both strand and underwater pelletising operations used in conjunction with its M-USG and P-USG underwa- ter strand pelletising systems and the new PEARLO underwater pelletisers. The company says PURO is a closed-loop water system with several integrated water filtration options designed to convey and cool pellets as they are transferred from the cutting chamber to the centrifugal dryer. The system can be used with a broad range of materials and is available for pellet-production rates ranging from 70-36,000 kg/h (154-79,400 lb/h) and for water flow rates from 10 to 250 m³/h. Frank Asmuss, Global Product Manager Pelletising at Nordson BKG says micro-pellets and pellets for foam,
38 COMPOUNDING WORLD | January 2017
www.compoundingworld.com
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