Why Crushing Is Critical in Plastic Recycling

Crushing is the foundation of plastics recycling. It reduces bulk volume, liberates contaminants, and prepares material for washing, separation, and pelletizing. The core principle is breaking material integrity through shear force, impact force, or a combination of both. Equipment falls into two main categories: cutting machines (shredders) for size reduction and crushing machines (granulators) for fine grinding.

Matching Equipment to Material

Plastic crushers / granulators — Best for soft, small, or pre-broken materials: PE film, bottles, thin-walled containers
Shredders (single or double shaft) — Built for large, bulky, or rigid items: EPS blocks, extruder purgings, woven bag bales, pipe sections
The key is matching feedstock size and rigidity to the machine’s torque, blade geometry, and chamber design.

The commonly used crushing equipment has different kinds of compression type, impact type, shear type, knock type and grind type. The choice of crushing equipment mainly depends on the type, shape and the degree of the grinding material. Different materials should be used in different crushing equipment. Hard PVC, polystyrene, organic glass, phenol-formaldehyde resin, urea formaldehyde resin, polyester resin, etc. are brittle plastic. They are fragile brittle, once compressed, are very easy to broke into small pieces, this type of plastic is suitable for crushing.

How to Select Crushing Equipment

By material behavior:

Ductile / tough plastics (PE, PP, PA) — Use shear-type equipment. Concentrated shear force overcomes their tendency to stretch rather than break

Elastic / soft materials (rubber, TPE, certain foams) — Require cryogenic pre-cooling to embrittle before crushing, or specialized low-temperature grinding

By target output size:

Large fragments (50–200 mm) — Shredders with compression or impact action

Medium chips (10–50 mm) — Shear crushers or secondary shredding

Fine powder (< 1 mm) — Grinding mills with collision and friction mechanisms

FAQ: Plastic Crushing

Can I use one machine for all my plastic waste?

No single machine handles every material optimally. A shredder for bulky rigid waste, a granulator for film and bottles, and a grinder for powder production is a typical three-stage setup. Running mixed material through one machine produces inconsistent output and accelerates wear.

Why does my film wrap around the rotor instead of cutting?

Film is low-density and elastic. Standard rotors compress it rather than shear it. Solutions: use a shredder with larger feed opening and tearing blades, add a ram feeder, or pre-compact the film into denser form before crushing.

How do I prevent heat buildup during crushing?

Heat softens plastic, causing it to gum up screens and stick to blades. Solutions: reduce rotor speed, increase blade-to-screen clearance, use water-cooled chambers, or switch to cryogenic grinding for temperature-sensitive materials.