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Recycling Plastics with Small Grinders, Shredders and Granulators



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Modern waste management is a complex process, partly because of the number of plastics used in modern packaging and manufacturing processes. Plastics are among the most versatile materials for creating containers for almost anything, as well as parts for nearly any type of equipment. Unfortunately, the same properties that make them versatile also make for difficult disposal. Not only are there several types of plastic to deal with, the waste care industry must also consider how to handle the contents of the containers.

Small grinders and granulators may offer a solution for businesses that deal with disposal and/or recycling of a small amount of plastics, as compared to large industrial manufacturers or recycling facilities. Whether these units are practical for a particular business depends on several factors, including the types of plastic to be processed, the contents of any containers and the amount to be processed as well as the time allowed for processing. We hope that this guide will help our customers in determining the suitability of this line of recycling equipment for their particular applications and which product best suits their needs.

General Information 

Grinders and granulators are, in general, both suitable for volume reduction of most rigid plastics. Small units may be effectively employed for reducing the volume of items like plastic bottles and other scrap in applications where the amount of input isn't relatively large. Processing of PET and HDPE containers and flat plastic scrap can be accomplished by units designed for those products. It's important to note that neither granulators nor grinders are generally suitable for shredding plastic films, such as grocery store bags. Feed for these units should generally be rigid enough to stand.

 Most small grinders and granulators are hand-fed. They may or may not include catch bins, and many are designed to accommodate standard storage drums for easy removal of the output. Some incorporate liquid collection which is, of course, important for processing items like oil bottles or containers that need to be rinsed, such as pharmaceutical bottles. In considering these units, the buyer will also need to keep in mind the ease of disposal of the discharged liquids.

Grinder or Granulator? 

In the most general terms, small grinders and granulators perform very similar tasks. The most significant differences are in throughput rate and volume reduction. The following facts should be of help in determining which is better for your application:

Speed vs. volume reduction: Because grinders simply pulverize the input feed by way of tearing and/or abrasion, they usually provide higher throughput rates than granulators. As an example, Small grinders with a 2 HP motor will typically be able to process several thousand bottles per hour or even up to a bottle per second whereas it would probably require a 5 HP or 7 HP Granulator to achieve the same throughput rate. That said, however, the buyer should be aware that constant feed rates at the top end of these ranges are likely to reduce the overall life span of a small unit.

Granulators, which usually utilize rotary knives, normally provide a greater reduction in volume in exchange for their lower throughput rates. The gravity-fed cutting chamber reduces the feed to a more uniform and usually smaller particle size. In many cases, the output from a granulator may be light enough to remove by way of a vacuum or blower and some small granulators can be fitted with this as an option.

Footprint: In a typical configuration, a grinder may require less physical space than a granulator. Small grinders generally require less length in the feed chute, since the material is mechanically forced by the internal mechanism rather than gravity-fed. This may also make them more portable, although at a typical weight of over 600 pounds, portability is probably more dependent on the type of stand configuration used. The equipment required for disposal of the output as well as any cast-off liquids must also be considered in calculating space requirements.

Noise: Granulators usually provide greater noise reduction than grinders. This is due both to the type of mechanism and the design of a typical unit. In an environment where noise is a consideration, a granulator may be the better choice.

Materials handled: In the case of smaller equipment (as opposed to mega-shredders/grinders), granulators may have fewer limitations as to the type of input. Small granulators typically handle heavier/thicker materials than grinders and some units are designed specifically for processing flat scrap.

General Considerations

Whether you're considering purchasing a small granulator or grinder, there are a few important features you'll want to be sure not to overlook. Among those are:

Power requirements: The electrical power supply available for operating a grinder, shredder or granulator will have a direct impact on the type of unit you purchase. You need to consider both the voltage requirements (typically 120V/60Hz or 240V/50Hz) and the current the unit draws.

Maintenance requirements: It's important to know what kind of maintenance is required to keep your unit in good working order and extend its life span. You should also consider how difficult the maintenance is to perform. Some items to keep in mind are knife/grinder replacement, chain replacement, lubrication and cleaning as well as overall life expectancy of the unit based on throughput.

Is Small Big Enough?

 Last, but certainly not least, before purchasing any small granulator or grinder, it's imperative to know whether it will handle your needs. At about $4,000.00 to $7,000.00 initial cost, these units are certainly among the easiest to acquire. Unfortunately, they are also unlikely to last as long as their larger, industrial-quality counterparts. A careful look at your actual throughput requirements could save thousands in replacement costs if a larger piece of equipment will better serve your applications. Running any piece of industrial equipment at its maximum capacity for long periods of time will obviously greatly reduce its useful life span.

 Another point often forgotten in purchasing this type of equipment is the manpower (pronounced man-hours) required to operate the equipment. Small grinders and granulators require hand feeding and the output may also need to be handled manually. In processes that require only intermittent operation of the equipment, small units may be sufficient. If your process requires constant or frequent operation of the volume reduction equipment, it may be more practical to consider a larger unit that can be dump or conveyor fed and/or equipped with automated output handling, such as thermoforming.


 We hope that this quick overview of small grinders and granulators has provided our customers and prospective customers with a better overall understanding of the equipment and its applications. As always, we encourage you to contact us for more information on any of our units before purchasing.

Contributor / Editor - Matt Kennedy - Refer questions to info@wastecare.com  

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