Grinders & shredders show their teeth at Western Plastics Expo.

Granulators that operate at shredder speeds and shredders with the one-pass size-reduction capability of a granulator mark some of the abundant product introductions in scrap reclaiming at the recent Western Plastics Exhibition (WPE) in Long Beach, Calif. Two examples of new single-rotor shredders were another interesting development on display.

UNUSUAL DESIGNS DEBUT

New model 1012BP from Battenfeld Gloucester Engineering Co.'s Gloenco-Newport Dir., Newport, N.H., is said to be the first granulator that operates in the 100-rpm range. Low speed reportedly reduces production of fines and noise while enhancing the life of the blades. This machine has one bed knife and a six-knife rotor and provides a double scissors cut. The knives are hard-coated to handle glass-filled materials. The gear-reducer drive is connected to the rotor through couplings, not belts. The 200-lb/hr unit is priced at $12,000.

A new-generation rotary grinder from ReTech Industries Inc., High Point, N.C., is said to combine the low rpm of a shredder with the one-pass capability of a granulator. Three models are available:

* RG42 has a 15-in.-diam. rotor with 27 knives, 25-74 hp drive, rotor speed of 120-150 rpm, and output of 200 to 5000 lb/hr.

* RG52 has a 15-in. rotor with up to 37 cutters, 40-100 hp drive, rotor speed of 90-150 rpm, and throughputs from 500 to 15,000 lb/hr.

* RG72 has a 20-in. rotor with 53 cutters, drive of 125-200 hp, 90-150 rpm, and throughputs from 1000 to 25,000 lb/hr.

MORE NEW GRANULATORS

Gloenco also unveiled its 1012 single-shaft auger granulator, designed to handle sprues and runners from two injection presses. It has a straight-drop hopper mounted above the single auger screw. The 10-hp unit operates at 400 rpm and processes about 250 lb/hr.

Six new models constitute the new HP line of compact granulators for bulky material size reduction at 90 to 750 lb/hr. They're manufactured by Morita Seiki Kogyo Co. of Japan and offered here by GRT Inc., Sun Valley, Calif. A straight drop-through feeding chamber leads to a deep groove cutting chamber which holds staggered segmented rotor blades (three welded knife tips on each blade segment, with a bolt-on version and two blade design optional). Compact flywheel design saves space.

New GP series of granulators from MPG Service & Sales Inc., Hillsboro, Texas, processes blow molded scrap at 200 to 2000 lb/hr. Sized from 8 x 10 to 12 x 55 in., the units feature a water-cooled cutting chamber and special rotating end disk, fitted with a fan to keep dust inside the machine. Three or five D2 steel knives are mounted on an open rotor that turns at 600 rpm. Swing-down cradle facilitates easier cleaning. Prices range from $4000 to $22,000.

MPG also introduced the model 1120 as an addition to its MP line. It has an angled C-shaped feeding chamber, helical segmented rotor with adjustable knives, two bed knives, and a mounted front plate that can attach a conveyor or take-off robot. Operating speed of 460 rpm generates outputs of up to 700 lb/hr.

A wide range of options for motor size, rotor speed, cutting design, soundproofing, and other features is offered on the new Force series of tangential-feed granulators from Rapid Granulator Inc., Rockford, Ill. These units are larger than Rapid's SR series but smaller than its other beside-the-press models. Three sizes of 8 x 10, 8 x 14, and 8 x 19 in. have either staggered or open rotors. A third bed knife is optional. Motors from 5 to 15 hp deliver 300-500 rpm. Soundproofing or evacuation options are also available. The machines are priced from $7000 to 89800.

SHREDDERS GET BETTER

In shredder technology, the newest development is units with a single rotor that shreds material against a comb-like array of stationary teeth. Single-rotor shredders have been used in other applications but are new to plastics. As compared with standard twin-rotor models, single rotors are said to produce smaller and more uniform particles, thereby eliminating the need for a granulator to complete the size-reduction job. In addition, single rotors typically cost less and use less horsepower. While single rotors may be more attractive for smaller-volume needs, twin-rotor shredders may be capable of higher throughputs and can handle higher levels of metal and other contamination.

One example of the new single-rotor models for plastics is the Uni-Shear from SSI Shredding Systems Inc., Wilsonville, Ore. Hard-to-grab materials like purgings and even off-spec bowling balls can be downsized to pieces from 3/8 in. to 8 in. Three models (SR-250, SR-375, and SR-500) feature a horizontal hydraulic ram feeder, a rotor of 10, 15, or 20 in. diam., and 30 to 102 cutter knives that are reversible and replaceable. Rotor speeds range from 45 to 120 rpm depending on the model. Hydraulic or electric motor sizes are 25/30 hp, 60/100 hp, or 100/150 hp. All machine operations are controlled by PC. The machines are priced at $50,00-60,000 for the smallest unit, and $100,000-130,000 for the larger machines.

New Roto-Grind line of single rotor shredders from Granutech Saturn Systems Div. of MAC Corp., Grand Prairie, Texas, shreds large, bulky parts at 500 to 3000 lb/hr. Four models (M50, M80, M110, and M160) have a hydraulic ram feeder in the hopper to push material onto the multi-cutter rotor. Rotors are 7-20 in. in diameter and motors are 10 to 125 hp. All models reportedly run at noise levels no higher than 85 dbA. Prices start around $30,000.