The Short Answer

·         A true shredder typically does NOT have a mesh or screen.

·         A crusher or granulator (which are often colloquially called "shredders") almost always DOES have a replaceable mesh or screen.

The confusion arises because the terms "shredder," "crusher," and "granulator" are used interchangeably in many contexts, especially by non-specialists.

Detailed Explanation: Shredder vs. Crusher/Granulator

Here’s how to tell them apart based on their function and design:

1. Plastic Shredder (No Mesh)

·         Primary Function: Size reduction through shearing and tearing. It's designed to take large, bulky items (like plastic barrels, pipes, large containers) and rip them apart into smaller, irregularly shaped flakes (often called "shreds").

·         Design: Uses two counter-rotating shafts with hooked or staggered blades that grab, shear, and tear the material.

·         Output Size: The output size is not controlled by a screen. It is determined by the distance between the rotating shafts and the cutting blades. The pieces are relatively large (e.g., 20mm - 100mm) and not uniform.

·         Common Uses: Pre-breaking large items for easier handling, volume reduction for transportation, or as a first-step size reduction before a granulator.

2. Plastic Crusher / Granulator (Has a Mesh)

·         Primary Function: Size reduction through cutting and grinding. It is designed to take smaller plastic parts (like injection molding sprues, rejected toys, bottles, or pre-shredded flakes) and cut them into small, uniform granules or pellets.

·         Design: Uses a rotating rotor with multiple knives that pass by fixed bed knives, scissor-cutting the material. The crushed plastic is forced through a screen or mesh.

·         The Role of the Mesh: The screen is a perforated metal plate that acts as a filter and size controller. Pieces of plastic are cut until they are small enough to fall through the holes in the screen. The size of the holes directly determines the final size of the plastic granules.

·         Output Size: The output is small (e.g., 3mm - 12mm), consistent, and ready for recycling or reprocessing.

·         Common Uses: In injection molding facilities for recycling sprues and runners, in recycling plants for creating clean, uniform regrind.

Why the Confusion?

In many countries and casual conversations, any machine that breaks down plastic is called a "shredder." You might hear someone say, "Shred those bottles," when they technically mean "crush those bottles."

When purchasing or discussing equipment, it is critical to describe your:

1.       Input material (what you are putting into the machine).

2.       Desired output size (how small you need the final pieces to be).

This will help a supplier determine if you need a true shredder, a crusher, or perhaps even a two-stage system: a shredder to break down large items first, followed by a crusher with a mesh to create a uniform final product.