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—View
a list of manufacturers at the bottom of the page
With many jurisdictions
enacting more stringent regulations regarding the recycling
of consumer and industrial waste and by-products and as
it becomes more fiscally sound to recover materials for
re-use, re-processing or selling, increased demand by recyclers
for plastic granulators and shredders is an unquestionable
fact.
For some recyclers, shredding
plastic prior to feeding the material into a granulator
is a necessity.
 Granutech
Saturn Systems Inc. manufactures a product line known as
Roto-Grind Shredders, a complete line of single-rotor horizontally
fed shredders. With this machine design, material is horizontally
forced via an electric hydraulic push ram into a rotor with
multiple cutters.
“Typically, clients
are processing plastic hard scrap or film in a bale form,”
says Damon Dedo, Granutech’s sales director. “We
commonly recommend our electric-hydraulic drive because
it provides much more rotor torque. This satisfies the various
demands in terms of system capacity and product sizing.
“Another benefit
of this machine type is the large feed chamber sizes,”
he adds, “As a result of oversized feed hoppers, operators
can load material into the feed chamber and do other things.
Our machines are very automated and are suited for minimal
supervision.”
These shredders can provide
product size reduction down to .5 inch particle size. The
machines are available in 8 models, starting at 20 hp and
upwards to 400 hp. In terms of capacity, the shredders can
process materials at rates between 1,000 and 10,000 pounds
per hour and more.
Roto-Grind shredders can
process drools and purgings, injection molded parts and
numerous types of film or fiber.
In terms of maintenance,
the machines can operate 24/7 and are powered by 460 volt/3-phase
electrical power. Typically these machines require a blade
rotation every 8 to 10 weeks (when processing film) and
the replacement of the blades after a similar time frame.
“For the most part,
blade maintenance is the majority of the maintenance you
should really expect,” says Dedo.
Rapid Granulator Inc. offers
a selection of 46 different granulators, whose horsepower
ranges from .5 to 400 and they have the capacity to process
scrap material at a rate of 10 pounds to 10,000 pounds per
hour.
“They are all based
on the diameter of the rotor – the smallest is 6 inches
and the largest is 32 inches,” said Kirk Winstead,
Rapid Granulator’s president and CEO. “Custom
design is our business. The cutting chamber itself is basically
configurable among standard options. Getting complex parts
to feed without producing flyback and noise are main challenges
with design.”
The company also produces
intake and evacuation systems. The most common intake system
is the conveyer, which works well for basic parts and materials
that have either passed through a shredder or are capable
of being loosely stacked and fed. Continuous motion is used
mainly for film, which is primarily handled by either a
roll-feed system or the use of a hose feeder that pulls
tubing from a reel.
The processed material
is evacuated into boxes, silos or various other containers
via negative or positive pressure. The company also produces
equipment for dust containment, as well as dust separation
that enhances the quality of the recycled product.
To protect the granulator,
Rapid has feed sensors and metal detectors, and for conveyer
systems, the ability to distinguish ferrous and non-ferrous
materials. Machines can be shut down through a zero-speed
switch.
“For example,”
says Winstead, “if the normal rotor speed is 600 RPM
and if it senses that the rotor speed has fallen below 200
RPM, it will anticipate a problem and shut down the machine
automatically. That can be for metal or anything that is
too big or hard to cut.”
As for maintenance, the
majority is for sharpening the knives, replacing the knives
and replacing the screens.
Rapid has clients and locations
across the globe. “Rapid is the inventor and pioneer
of adjustable rotating knives,” says Winstead. “Every
machine we build is done with maintenance in mind –
our clamshell-type opening and closing features –
which gives plant personnel total access to the rotors,
hopper and screen.”
 Cumberland
Engineering Inc. offers more than 50 models of granulators,
which range in horsepower from 2 to 600, have capacities
between 100 and 15,000 pounds per hour and permit customers
a choice between four primary types of rotors. The open
wing rotor with its variations – the slant cut and
twin shear is the most widely applied design. The staggered
rotor is designed for lower RMP and less generation of sound.
The hog rotor is a very large, massive and solid rotor,
desirable for large or solid masses such as purging that
comes out of an extruder or molding machine.
The granulators are driven
by electric motors, although some applications have led
to gas drives or diesel engines and hook-ups to generators.
“We supply fully
integrated systems where we can provide the in-feed conveyers
or any pre-staging equipment,” says John Farney, Cumberland’s
national sales manager, “as well as extraction equipment.
Our forte is providing the proper solution to any application,
be it small, large, complex or simple.
Maintenance is essentially
caring for knives, as well as replacing screens.
As well, you have to lubricate
the bearings, otherwise they will seize up on you and you
have to maintain belt tension on the drive belt. You also
have to do some routine checks such as visual inspections
to make sure that the safety interlocks are in place.”
Cumberland granulators
are made of solid steel. “Solid steel makes a stronger,
more massive machine and this mass is directly correlated
to durability and safety,” says Farley. “Simply
put, granulators are designed to destroy polymeric scrap
and turn it into a usable commodity. This destruction demands
the strongest and safest products and methods possible.”
Cumberland’s designs
incorporate elements for added performance such as rotational
side walls in cutting chambers and safety elements such
as lockable/pinnable rotors to assist in maintenance operations.
Based in Toronto, Canada,
Rotogran International Inc. manufactures a line of high-speed
granulators with the majority of its customers located in
North America.
Designed mainly for use
on soft and hard plastics and rubber, the strength of the
granulators ranges from 5 to 700 horsepower, have a capacity
to process 300 to 400 pounds to 15,000 pounds per-hour and
are powered by a totally enclosed electric cooled motor.
Similar to the other granulators
featured, blade sharpening and replacement is the major
maintenance requirement.
“Keeping the blades
damage-free means keeping metal and contaminants away from
them – one broken blade will in turn break the rest
of the blades,” says Mike Cyr, Rotogran’s vice
president of sales. “As blades wear down, they become
dull and the machine has to work harder, the quality of
the regrind drops and so does the quality.”
 As
with the other firms, Rotogran designs custom systems for
its clients complete with in-take and evacuation systems.
Ensuring contaminated substances
do not enter the granulator is an essential element for
Rotogran products. To do this, Rotogran has a metal detecting
system for the conveyer in-feed. This type of system is
extremely sensitive and is commonly used in the food industry.
“To combat wear from
dirty plastic, we offer replaceable inserts,” says
Cyr. “When they start to wear down, you unbolt the
inserts and put in a new set. Wear plates inside the chamber
and along the sidewalls can be made from various materials
such as mild steel, tungsten carbide coated steel, quenched
and tempered steel or tool steel.”
A key feature for any size
reduction system is the need to provide air-flow through
the granulator with a blower/cyclone system.
By evacuating with a vacuum
through the bottom drawer, the whole machine is cooled,
plastic material is assisted through the screen area and
production is increased while the quality of the regrind
remains high.
“To increase efficiency,”
says Cyr, “the system can be designed to have the
in-take, granulator and evacuation system communicating
with each other to monitor the feed, amperage draw and with
sensors, inform you when the evacuation boxes are full.”
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