TECHNOLOGY | SIZE REDUCTION


caps, closures, fitments, small engine and appli- ance parts. Production involves challenging materials, such as a 33% glass-filled nylon, which runs on a 500-tonne injection moulding machine running a 9s cycle, producing sheetrock anchors. The granulator is a Wittmann Battenfeld Junior Double Low Speed screen-less granulator. “With a standard granulator, there are a variety


Above: Granulation at Hoffer Plastics involves challenging materials, such as a 33% glass-filled nylon


different plastic parts, such as reject housings, sprues and purgings, can be charged together. The vertical design of the mill allows easy access to the rotor and cutting knives for rapid cleaning, which significantly reduces downtime. Hosokawa Alpine has recently supplied the


Polyplex PPC 50/120 to MG Plast, which was looking for an automated and cost-efficient recycling solution that could be implemented flexibly and in a cramped working space. End prod- ucts with a fineness down to 5 mm are produced in a single comminution step. The machine design allows the feed material to be non-uniform in shape. Small trimmings can be fed together with heavy machine purgings or large-volume blow mouldings. The vertical rotor shaft allows easier access to the grinding chamber, rotor and knives. Following successful tests in its application testing centre, the machine was validated in operation at the customer’s premises. During a four-week validation phase, the Polyplex PPC 50/120 was integrated into the recycling process of plastic production waste at MG Plast. Plastic chunks and trimmings constituted the main feed materials in this process. The challenge was in the self-dosing of the system, as well as in the size reduction of large and heavy machine purgings to granulator fineness in one step. The plastic purgings are charged to the machine with the aid of an intake unit. The feed material can be fed continually or in batches. A pusher feeds material towards the shredder, which takes care of the preliminary size reduction. The pre-comminuted material then falls into the granulator zone located on the same shaft. The material is then comminuted to the desired end- product fineness and is discharged pneumatically. Wittmann Battenfeld has supplied granulators for US company Hoffer Plastics, an injection moulder processing over 20m lbs (9.1m kg) of plastic and 3 billion parts every year of primarily


24 PLASTICS RECYCLING WORLD | November/December 2020


of challenges with the 33% glass-filled nylon material that we run,” says John Lederer, Mainte- nance Manager at Hoffer Plastics. “Primarily though, the blades on them will dull far too fast for our needs, and a dull blade results in dusty, poor quality regrind. Having a grinder stay sharp longer and be able to be cleaned and maintained easily seems like a simple thing, but it really does save us a lot of time and money on every job we do.” Wittmann Battenfeld says that its granulator has a low speed and durable design to allow for longer blade life and better quality regrind of even the toughest materials. The granulator is easy to use and clean, two features that are integral to a longer blade lifespan and continued high quality output regardless of the material being used. Hoffer Plastics now has four of Wittmann Battenfeld’s Single Low Speed screen-less granulators and two of the Junior Double Low Speed screen-less granulators. Wittmann Battenfeld adds that the granulators


are also flexible, with options and add-ons that make them effective for any variety of job. One such option that Hoffer Plastics has found particularly useful is the integration of magnets. “One great feature of the grinder that we’ve been able to take advantage of is the optional magnets,” says Lederer. “The magnets work to prevent scrap metal from getting through into the regrind, and the flexibility and connectivity has been great. We purchased an upright conveyor and we were able to key this grinder to that conveyor so that all runners drop past a magnet, pulling out scrap metal and keeping the regrind from getting contaminated.”


CLICK ON THE LINKS FOR MORE INFORMATION: � www.cmg.it � www.hellweg-granulators.com � www.dreher-aachen.de � www.conairgroup.com � www.exact.it � www.herboldusa.com � www.herbold.com � www.rapidgranulator.com � www.zerma.com � www.hosokawa-alpine.com � www.wittmann-group.com � https://hofferplastics.com


www.plasticsrecyclingworld.com


IMAGE: WITTMANN


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