Granulators quickly break down plastic and other materials so they can be more easily recycled. The electric motor in a granulator turns a rotor with cutting knives, all within a closed chamber. There are variations in both chamber design and positioning of the cutter knives, but most plastic granulators perform the same basic function. The three types of rotors in most granulators include the scissor cut (or double scissor cut); the Chevron or V-type rotor; and the helical rotor design. Granulators break down plastic waste and other materials to aid in recycling, resulting in less waste sent to landfills.
“The Cumberland Recycling companies provide the widest array of granulators available to the plastic reclamation industry. With over 50 models of granulators, and literally 1,000s of configurations and designs, Cumberland is the largest supplier to the growing reclaim market,” said John Farney, national sales manager.
Operational features include solid steel construction, high-mass/high-durability designs, multiple rotor designs, multiple knife configurations and geometries, and special reinforcement options for high wear operations. Cumberland serves the post-consumer, post-industrial and e-waste, bio-mass, C&D, paper, secure file destruction, injection molding, thermoforming, extrusion and rotational molding markets.
Farney said, “Our product array offers throughput performances ranging from 100 to 10,000 lbs. per hour, and allows the reprocessing of the smallest injection-molded part, the largest blow-molded part and everything in between. We supply the safest, easiest to maintain, most durable and longest-lasting units in the marketplace. The longevity of our products is due to the use of solid steel components, which are precision manufactured to a tight fit and finish, then dowelled and pinned together for a finished product that can be maintained for years of maximum output. Our world-class support staff and technicians also help our clients operate at peak performance levels.”
Farney noted that the resin reclamation market, whether post-consumer, post-use, or scrap from manufacturing, is rising. “Resin prices remain volatile due to crude oil and natural gas prices, and reclaimed resin continues to present value to the manufacturing industries. The ‘value vs. virgin resin’ factor can present a tremendous cost savings. The practice of sending collected resin to Asian markets has reversed, and creative minds recognize the potential involved as legislation continues to affect recycling and there is an increasing effort to avoid sending valuable commodities to landfills. Annually, Cumberland supplies over 1,000 units to various markets in the reclaim of valuable scrap in post-use or manufacturing situations. We also manufacture shredders, pulverizers, pelletizers and sort/separation systems, and we can design and configure a system for most any application,” he said.
David Lefrancois is president of Herbold Meckesheim USA, a subsidiary of Herbold Meckesheim Germany. The company designs, manufactures and installs durable, high-quality size-reduction equipment (granulators, shredders, grinders, pulverizers, etc.) and wash-line systems for the plastics industry, specializing in the recycling of industrial and post-consumer plastics. Herbold’s line of granulators includes heavy-duty, general-use, force-fed and compact machines. According to Lefrancois, “The SB Series granulators employ a patented screw-feed mechanism and they are quieter and more efficient than gravity-fed size-reduction equipment for granulating PET (polyethylene perephthalate) bottles and other recyclable plastics.”
Intended for dry or wet operation, SB Series granulators are capable of processing up to eight tons of plastic per hour. Materials to be granulated are delivered from the unit’s hopper to the cutting chamber by one or more conveyor screws mounted at an angle (45 to 90°) to the rotor axis. Throughput is 30 to 50 percent above that of gravity-fed machines with cutting chambers of the same size. SB granulators can also be used for secondary size reduction of pre-shredded plastics, and accept a wide selection of interchangeable screens to control particle size. The cutting action of these granulators is a true scissor-cut, providing cleaner cuts, higher capacity, fewer fines and less noise.
Lefrancois explained that Herbold Meckesheim granulator knives can be removed easily and safely and adjusted in a fixture outside the unit. “This allows for more precise adjustment of the cutters, resulting in optimal size reduction, higher throughput and reduced downtime. Knives last longer because their design provides 18mm of regrind capacity, nearly twice that of most competing models. A diagonally-split housing allows complete access to the cutting chamber for faster maintenance and rotor bearings positioned outside the cutting chamber keep grease from contaminating product,” he added.
Regarding the ongoing debate about how to best process recycled post-consumer plastic household waste, “a convincing case can be made for wet grinding. After a few hours of dry cutting, the blades in a typical cutting chamber get hot enough to melt plastic and contaminants (paper labels, adhesives, dirt, food residues, etc.) together, which makes subsequent cleaning more difficult. Processing with water keeps the cutting chamber cooler, and the friction in the cutting chamber doubles as an intense washing process. Also, wet grinding almost triples blade life between sharpenings, when compared to dry grinding. These benefits carry over to the machine’s internals and sizing screen,” Lefrancois stated.
Rotogran International is a North American manufacturer of size reduction equipment for the plastics recycling industry. Mike Cyr, vice president, stated, “We design single pass, high capacity granulators capable of reprocessing plastic scrap into valuable regrind, regardless of its original shape or size. Our products offer a combination of an offset cutting chamber with a tangential feed throat, and an open rotor design. This makes it possible for scrap to be forced directly into the cutting circle and eliminates material bounce while dramatically increasing overall production rate.”
Also, the twin, solid steel flywheels provide the inertia required to collapse and cut through large bulky parts without losing rotor speed. “The double-scissor cutting design of our chamber creates a side-to-side cutting action, utilizing the entire chamber to spread the workload evenly. Easily replaceable wear plates strategically placed within the cutting chamber walls save time and costly repairs when dealing with dirt and abrasive materials. Hydraulically-assisted hopper and screen operation dramatically decrease down time for routine blade changes and maintenance,” said Cyr.
He said that within the recycling industry, the WO and TN Series units are the most popular, with 26” or 36” cutting circles and motor horsepower ranging from 100 to 500. Hopper openings range from 36” to 72” wide by 30” to 44” deep. Production throughput is rated from 3,000 to 10,000 lbs. per hour. Rotogran also offers loading conveyors, metal detectors, permanent magnets, blower or cyclone evacuation systems, dust separators, rotary air-locks, surge bins and box dumpers.
Cyr noted that as the price of oil rises and the value of plastic regrind follows along, recyclers demand rugged, solidly-built equipment, which can withstand the extremely harsh grinding conditions they encounter. He said recyclers are interested in quality, reliability and production – not bells and whistles.
All Rotogran products are designed and manufactured in North America. “Our clients seem to prefer the durability and value of older, refurbished equipment and are leery of the risk associated with inexpensive products that may be manufactured offshore. The ability to source parts and quickly return to production when disaster strikes, is crucial to survival in this market. We’re well-known for supplying heavy-duty equipment that exceeds our customers’ expectations while remaining sensitive to today’s economic reality,” said Cyr.