Canadian Plastics

Superb SIZE Reduction

The triennial NPE show is traditionally the one event that all North American suppliers to the plastics industry gear up for, with the introduction of innovations aimed at giving them a step up on the...

October 1, 2000   By Michael LeGault, editor



The triennial NPE show is traditionally the one event that all North American suppliers to the plastics industry gear up for, with the introduction of innovations aimed at giving them a step up on their competitors. This year the strategy certainly applied to manufacturers of size-reduction equipment as companies introduced new lines of equipment designed to provide processors with greater flexibility, automation and efficiency.

With its Single-Shaft Rotary Grinder, ReTech Industries is offering what it claims is the first advancement of major proportions in size reduction and reclamation of plastic materials in 50 years. This relatively new concept has roots in Europe, but is fast becoming the standard in size-reduction technology, according to the company.

ReTech’s Single-Shaft Grinder accepts large, dense and bulky feedstock into a voluminous hopper. The feedstock can be large bottles, dense purgings, large scrap parts, thick-walled pipe scraps, baled or rolled film and other materials, including composites, wood and paper. A hydraulic ram auto-feeds the material to the cutting rotor. Programmed logic controls monitor and adjust the ram feed to control the resistance on the cutting rotor and the amount of material being fed. A counter knife fits precisely to the rotor’s cutting profile to provide a scissor cut on the material. Four-sided cutting inserts can be rotated for longer life and are easily replaced. Ground material then passes through a screen to produce a particle consistency. ReTech says the system, in many cases, eliminates the need for two-stage reduction, or can be configured to work in concert with granulators to provide a two-stage reduction system in applications requiring pre-sizing of feedstock prior to granulation. ReTech is offering its Single-Shaft Grinder in three models, the RG-42, RG-52 and RG-72, which vary in maximum throughput from 5,000 lb./hr. to 25,000 lb./hr. ReTech and Cumberland Engineering have recently announced that Cumberland will act in the capacity of a distributor for ReTech’s Single-Shaft Grinders.

Rotogran has introduced valuable new features to its line of single-shaft, low-speed, high-torque rotary shredders that take up less room and will make it more economical to run size-reduction operations in-house. Micro cutting teeth produce a smaller, high-quality granule from purgings which can be loaded directly from the shredder into an extruder in a single step, without screens.

“Quality and throughput are the two key issues in any size-reduction operation,” says Mike Cyr, vice-president sales. “Putting a screen on your system dramatically decreases your throughput and also reduces quality.”

Cyr points out that one of the unique features of Rotogran’s cutting system is the use of off-the-shelf tungsten carbide cutting bits that can be inserted into the rotor. Each bit can be turned four times before replacement, leading to significant savings. Also, a new intermeshing square-cut rotor eliminates wrap-around when processing film and sheet by sealing the gap between rotor and stationary knife. As well, the Rotogran machines come with a new operator panel which displays diagnostic messages and scheduled maintenance reminders, and an optional patent-pending built-in tramp metal detector. Size offerings range from 15 hp with a 22 in. feed opening to 150 hp with a 77 in. opening, and rotor diameters of 11 in., 14 1/2 in. and 20 in.

SMALLER AND LARGER GRANULATORS LAUNCHED

Granutec’s TFG1212 granulator with combination front and top feed hopper is designed to facilitate manual, robot or conveyor feeding. The front feed hopper accepts tough, bulky parts, sprues and runners, light sheet, small diameter pipe, extruded profile and film. Robot or conveyor feeding is accommodated through the top hopper opening. The TFG1212 comes with a 12 in. by 12 in. throat size, a 7.5, 10 or 15 hp motor and a maximum throughput of approximately 400 lb./hr., depending on the application. Double scissors rotor cutting action produces uniformly cut granules with minimum fines.

SRS Corp.’s new model XM1820 granulator was developed for press-side granulation of large, thick-walled parts. A small footprint allows the XM1820 to be used in size-restricted areas. The main components of the system are a modular rotor, a material pusher and an auto stop/reverse electrical system. Each modular segment has four reversible D-2 steel cutters. The cutters can be reversed and used two times.

Hosokawa Polymer Systems is introducing to North America three new product lines manufactured by its sister company Hosokawa Alpine. They include the company’s rugged Rotoplex granulators designed for film recycling and purgings; the CL Line for large part recycling, especially hollow plastic items such as bottles and containers; and the AFS Line of fine grinding mills for producing fine powder particles for PE rotomolding and PVC for pipe and profile extruders.

Cumberland Engineering Corp. has introduced their newest and largest commercially available granulator, the Model 3263 high-capacity granulator. Typical applications for this machine are heavy purgings, blow-mold flashings, sheet, pipe, large blow-molded parts, x-ray films, packaging films and large-capacity post-consumer products.

Temperature Corporation’s One-Step-Granulator combines the advantages of a one-shaft shredder with those of a conventional granulator. The addition of a hydraulic ram increases throughput. It is especially suitable for continuous infeed as well as sequential shredding of large parts. Maximum pieces up to a volume of 92 gallons and weight of 1000 lb. can be processed with a 5/16 in. screen.

Ball & Jewell has expanded its line of size reduction equipment with the introduction of the Explorer Screenless Granulators. The Explorer is a new generation of quiet, low speed, low rpm granulators designed for efficient size reduction of sprues with minimum fines and dust. The new line of Explorer machines come with an array of features to reduce downtime and make changeovers faster and easier. These include a clamshell cutting chamber opening for full access below the rotor; removable segmented chambers for easier cleaning and cutter removal without rotor disassembly.

Maguire Products, Inc. has developed a smaller version of its S-30 Shuttle Granulator for purgings and other heavy-duty scrap. The new S-20 model has a smaller scrap containment chamber (20 in. by 30 in.) than the existing S-30 unit (30 in. by 30 in.) and a smaller footprint, but has the same overall size and operates identically, according to Kevin Cabana, general manager of the U.S. Granulator Div.

“With raw material costs ranging from forty cents to several dollars per pound, the weight of plastics scrap is an even greater issue for processors than its size,” says Cabana. “Shuttle Granulators generate high-quality regrind from scrap that is very large, very heavy or both.”

Hosokawa Polymer Systems, Inc. offers a Slow Speed Series of granulators that can be fed manually, by robot or conveyor. With a rotor speed of just 200 rpm, the granulators generate fewer fines and are less subject to wear, even when processing tough, glass-filled materials, according to the company. Because the Slow Speed Series uses motors that are about 40 percent smaller than a comparable high-speed machine, they consume less energy and run quieter.

Size-reduction technology continues to evolve, making in-house reclamation of scrap and purgings a more economical, hands-off activity.


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