Plastic manufacturers often involve injection molding, thermoforming, extrusion and blow molding. In the above processes, some amount of plastic waste (e.g. left-over, flesh, trimming, purging, sprue, gate and runner) and plastic rejects (non-conforming parts) are created.
If the byproducts of plastic processing go to waste without size reduction, they result in taking up space and waste of materials. A better way to process is turning the plastic scrap and rejects into reusable regrind by size reduction. Regrind is also known as flakes, pallets, recyclettes or recycled granules, whose property is considered close to the resin.
Common plastic types include:
There are 2 machines that often deal with plastic scrap and plastic waste: granulators(crushers) and shredders.
As a primary size reduction, shredders break down large parts into smaller “chunks” in 30-60mm. Comparing to granulators, this can be a cost-effective alternative to cutting up parts manually. Shredders are often found in commercial and industrial recycling because they are effective on a wide selection of materials.
Plastic shredders are increasingly being used by processors to reduce large parts (like purgings and lumps) to a size that can be fed into a granulator. Most of the shredders in the market are single shaft shredders, while double shaft shredders are for mixed waste and hollow objects. Three shaft and quad shaft shredders are also available.
Granulators are the secondary size reduction. They reprocess materials into fine particles. The final particles are the same as virgin resin so that they can be directly utilized by injection molding, extrusion, thermoforming and blow molding.
Plastic granulators typically can produce particles from 10mm to 12mm (1/8” to 3/4”) in size. The materials granulator can process tend to be small and medium, like shredded particles, plastic sprues and runners.
Granulators are most commonly seen beside the press, in-house recycling, in-line recycling, and central size reduction. They can be used in many recycling systems posed as an important size reduction machinery.
Wiscon launches a combination of a shredder and a granulator into a single unit, in which shredding and granulating can be achieved in one step. The size-reduction take place in one machine, saving space and transportation machine like conveyor.