You’ve been friended by the latest size reduction equipment
With the cost of materials going up and maintenance budgets going down, it’s critical that shredders and granulators be as user-friendly as possible. New designs can help transform your size reduction process from headache to hassle-free.
August 27, 2019 by Canadian Plastics
With the possible exception of ride-hailing apps like Uber, no product ever got worse by being made more user-friendly. And that probably goes double for something as inescapable as size reduction in plastics processing. Now more than ever, granulation is a vital step in the total production process. With the higher cost of materials combined with increased demands from end-users to include reground and/or recycled materials in the product, using regrind is no longer merely an option. So it’s good to know that new shredders and granulators boast more user-friendly features than ever, including easy access, removable parts, less blade wear, and more.
With the increasing cost of materials and shrinking maintenance budgets, it’s important that size reduction machines be designed for easy cleaning and knife maintenance. Which means that quick, safe access to the heart of the unit is critical. Now available in North America, Rapid Granulator Inc.’s Raptor series of single-shaft shredders has a unique, patented “open-hearted” design that makes the machines particularly easy to operate, service, and clean. According to Jim Hoffman, Rapid’s vice president, sales and marketing, a Raptor shredder can be in a completely open position in less than one minute after it has stopped running. “The front door is hinged on the side, and provides unrestricted access to the rotor and to the screen, which is mounted in the door,” Hoffman said. “Once the front door is open, the shredder hopper mounted on a rear hinge can be tilted back.” Once the machine is open, Hoff-man continued, all fasteners are accessible from the outside using air-driven tools. “The tilting hopper opens with an electrically operated jack, while the screen and granule bin can be handled by a single operator,” Hoffman said. “The screen cradle design doesn’t need bolts to be removed when removing the screen, and the granule bin slides out easily. The same tool is used to unlock the front door and to rotate the rotor.” As an option, Hoffman said, a light can be fitted to provide extra illumination. Rapid offers a total of 36 base configurations for the Raptor to handle various customer applications. “The Raptors can also be configured in the Rapid DUO concept, with a floor-standing granulator located directly beneath the output of the shredder,” Hoffman said.
Newly available for the North American market, Weima’s WKS series of general purpose, single-shaft shredders are designed to shred voluminous objects, tear-resistant fibres, and film. Depending on the application, the machines — the WKS 1400, WKS 1800, and WKS 2200 — are available with either hydraulic or power-belt drive. Various screen sizes are avail-able in the material discharge area, and screen segments can be changed individually. The shredders come with Siemens PLC control panels, and are suitable to run stand-alone or as part of a recycling line. On the user-friendly side, a swing ram on rolls is positioned inside the cut-ting chamber, providing for consistent infeed of materials; and an inspection flap inside the chamber allows for easy access for maintenance to clear any foreign objects that may have been introduced during the shredding process. Also, the shredders come equipped with hydraulic or power-belt drives, depending on the application. The rotor type also depends on the application: a V-rotor for lumps and large objects, or an F-rotor for fibres and film. The screen size can be chosen to fine-tune the final shredded product to the ideal size, including for reintroduction into a production line or for recycling.
It’s been exactly two years since Universal Dynamics Inc., the U.S. arm of Italy-based Piovan SpA, introduced a comprehensive line of granulators to the North America market, which are sold under the Piovan brand. The line encompasses small, beside-the press granulators through mid-sized and large granulators, with rotor diameters from seven to 24 inches, and machines designed for specialty applications such as thermoforming and post-consumer recycling. The range of granulators includes both in-line and front-of-press granulators for capturing thermoforming web scrap, as well as granulators designed to handle edge trim from extrusion. For blow molded parts, granulators are available with optional scooped rotors, which allow more area in the cutting chamber for handling large, bulky parts. The granulators come standard with a host of user-friendly, wear-resistant features, including disposable blades that allow knife inserts to be changed easily; and tangential cutting chambers, in which the geometry of the cutting chamber can be tailored to specific applications — instead of being cast, the cutting chambers are machined and fastened with dowels, so they can be easily dis-assembled to replace worn parts. In addition, the granulators for post-consumer recycling have a special finish to make them more resistant to wear; this anti-wear treatment is also an option for the rest of the line.
Vecoplan LLC has added a new hydraulically lifting shredder floor as a standard feature on two of the models in its workhorse V-ECO series of shredders. Designed to offer safe and easy access to the rotor, customers can remove extraneous material, adjust or exchange counter knives, or rotate and change the cutters. “Instead of having to open the door and take the screen out, the operator simply presses a button and the floor lifts hydraulically right at the rotor,” said Greg Parent, the company’s Canadian sales representative. “The operator can then walk under the machine from the rear to gain full access to the rotor, cutters, and counter knives to perform maintenance or remove tramp metal without emptying the hopper or having to enter the shredder.” The cutting chamber floor is an option on the two smaller V-ECO shredders — the 900 and 1300 — and is standard on the larger 1700 and 2100 models, Parent added. Another new user-friendly feature from Vecoplan is the ESC drive, a gearless drive with motor power of 50 to 200 hp. “The ESC drive is a special variable speed torque motor coupled to a synchronized drive flange for instant torque and speed adjustments based on process feed-back,” Parent said. “A digital encoder constantly evaluates the current drive conditions and automatically boosts efficiency in all operational conditions. This system eliminates the need for moving parts like gear reducers, clutch assemblies, or torque arms, which all require careful maintenance and provide opportunities for parts failure.”
NO WEAR, NO TEAR
The extremely abrasive nature of today’s glass-filled polymers and other tough materials is no laughing matter in the size reduction world: they represent a major cost factor in the machinery and, by dulling knives and causing other alignment problems, are responsible for the vast majority of granulate quality problems. As a solution, Rotogran International Inc. now offers removable, replaceable inserts for the wear areas of its granulator chambers. “The inserts are located at both sides of the rotor and at the wear points of the backplate leading into the bottom stationary blade area,” said Rotogran president Mike Cyr. “Inserts can be provided without any protective coating for use as a consumable product, or they can be tungsten carbide coated for extended life.” For this second option, Cyr said, the inserts are coated with a layer of tungsten carbide applied with a high-velocity oxygen fuel process that’s superior to the more common plasma process — it fuses the tungsten carbide particles to the steel insert with extremely high-density and negligible porosity, giving a typical hardness of 65 Rockwell C. “These inserts can be replaced without disassembling the entire granulator chamber and in half the time it takes for a typical blade change,” Cyr said. “Zero speed sensors, rotor locks, high-level bin sensors, amp meter overload relays, and smart conveyor feed systems are other user-friendly options our customers request, and we can supply all of these.”
Screenless granulators have always provided a number of user-friendly benefits: less noise; clean and uniform regrind for hard, brittle plastics such as styrenes, acrylics, and glass fibre-reinforced, mineral- and talc-filled engineering grade resins; and low-speed operation — typically between 27 and 32 rpm — which reduces wear of cut-ting tools and maintenance demands, enabling up to twice the maintenance interval of conventional blade granulators. Equipped with two rotors in the cutting chamber for large sprues and parts, Wittmann Battenfeld’s Junior Double series screenless granulators are typically used offline, located away from the process. “The Junior Double series has an optional automatic reversing system that helps minimize block-ages in the cutting chamber and aids the granulation of thicker walled or tougher plastics,” said Christian Weiss, Wittmann Battenfeld Canada’s national sales manager. “The reversing system enables the machine to determine if resistance to the cutting blade is too high. If so, it reverses the rotor and repositions the part to allow cutting from a different angle. The Junior Double granulators also offer quick cleaning since there’s no screen to unplug — the customer has easy and complete access through the double-top opening, which exposes the whole cutting chamber.”
Herbold Meckesheim GmbH has also developed new possibilities to reduce wear costs: The company’s SMS series granulators can all be supplied with wear plates in the grinding chamber. The options range from basic replace-able wear plates in the top of the granulator and — depending on wear and tear — replaceable stator knife sup-ports all the way to screwed, replace-able rotor knife support plates.
A common maintenance problem, especially with older granulator designs, is that knife removal, replacement, and adjustment can be difficult and dangerous — for example, relying on a block of wood for safety while the operator is installing, adjusting or torquing down a newly sharpened set of knives on a movable rotor. Viper granulators from Conair Group, which replace a variety of granulators the company offered under various product names, simplify the knife maintenance process with safety switches and interlocks that make removal easy and safe — most importantly, safeties that reliably disable operation and prevent the rotor movement when the granulator is open for cleaning, screen access, knife/rotor adjustment or other lubrication or maintenance. “All Viper granulators offer tool-free access to the rotor chassis, with drop-down screen cradles that allow the operator to lower the granulator screen for inspection, adjustment or cleaning of the rotor assembly,” said Dave Miller, Conair’s general manager for size reduction. “Cutting chamber access is simplified thanks to hinged, tilting hopper designs and power-assist features to ensure that one person can safely open and handle even the largest Viper granulator hopper.” Also, Miller said, the bearings and rotor shafts of Viper granulators are protected by rotor-end disks that isolate them from exposure to granulate, dust, and fibres that might otherwise find their way into rotating machinery or interfere with proper lubrication.
Cumberland’s new line of beside-the-press granulators — the 7, 10, and 16 series — can be integrated with extruders and injection molding machines to process scrap directly inline. According to Tyler Check, Cumberland’s product manager for size reduction, benefits of the new granulators include safety, user-friendliness, application flexibility, durability, and performance. “The machines are compliant with ISO 12100 safety standards, and the cutting chambers can’t be accessed until the rotor stops,” he said. The new granulators have a viewing window that lets opera-tors monitor the material in the cutting chamber, Check continued, and the cut-ting chamber has wide-open access for easy cleaning and knife changes. Also, an improved discharge seal minimizes dust and potential regrind leakage, and a larger discharge bin doesn’t have to be emptied as often.
In the end, contract drivers for Uber might not make customers’ lives any easier; these new user-friendly size reduction features definitely will.