What is Size Reduction?

plastics size reductionThe overall goal of most plastics processing in-house recycling programs is to turn scrap and non-conforming parts back into a form and size that is similar to the new or virgin material being processed. This “regrind” will often have the proper material characteristics such as strength or optical qualities of the original resin and can be reused to make more parts. It’s both cost efficient and environmentally friendly.

Plastics processors use size reduction equipment widely alongside injection molding, blow molding, extrusion, and thermoforming processes, and it’s also used for general recycling purposes. There are basically three types of resizing equipment:
 





   


Granulators

plastics granulatorGranulators are very effective at reprocessing sprues, runners, and small to medium size parts. They typically generate particles from 1/8” to 3/4” in size, though most granulate runs between ¼” and 3/8”. Granulators are most commonly found near injection molding machines but are also used with other processes such extrusion, blow molding and thermoforming. There are basically three types of granulators: beside-the press, central and special units designed primarily for thermoforming. But there are many more granulator technology options that make a unit best for general purpose operation or specific applications.
 

 
   


Shredders

Plastics shredderShredders are for large or very dense parts. They can rip up large items into smaller pieces about 2” to 4” in size and are effective on a wide range of materials. Shredders reduce the time and effort required to manually cut up large parts. They can be used to efficiently reduce materials before going to the granulator. Like granulators, shredders also have a number of technology options that will suit them best for any given application.

   

 



Pulverizers

PulverizerPulverizers take 5/16” particles and grind them into powder. The powder is commonly used for compounding, blending, PVC recycling and rotational molding. They can grind a wide range of materials.

For this Size Reduction Knowledge Center, we will focus on granulators and shredders which are most commonly used by plastics processors.