Pulverising Recycling Machines vs. Granulators: Key Differences You Should Know

The key difference between pulverising recycling machines and granulators is particle output size: pulverisers reduce plastic to a fine powder, typically 20-80 mesh (roughly 0.18-0.85mm), while granulators produce coarser flakes or pellets, typically 3-10mm in size. Choosing the wrong equipment for your downstream process can result in material that's unusable for your specific manufacturing method, whether that's rotational molding, injection molding, or extrusion.

Below, we compare these two machine types across output size, mechanism, energy use, and the specific recycling applications each is best suited for.

Why This Distinction Matters for Your Recycling Process

Plastic recycling typically involves multiple size-reduction stages, and many operations actually use both machine types in sequence — a granulator first reduces bulk material into manageable flakes, followed by a pulveriser that further refines those flakes into fine powder for specific applications like rotomolding or powder coating.

Using only a granulator when your process requires fine powder (or vice versa) means your output simply won't work for the intended downstream application, regardless of how efficiently the machine itself operates.

How Granulators Work

Granulators use rotating blades (rotor knives) that cut against fixed stationary blades (bed knives) to shred plastic into smaller pieces. Material is fed into a cutting chamber and repeatedly cut until it passes through a screen of a specified mesh size, determining the final flake size.

Key Characteristics

• Output size: Typically produces flakes between 3mm and 10mm, depending on screen size.
• Material compatibility: Handles a wide range of plastics including rigid scrap, regrind, films, and even some fibrous materials.
• Energy efficiency: Generally consumes less energy per pound processed than pulverisers, since cutting requires less mechanical force than grinding to powder.

How Pulverisers Work

Pulverisers use a different mechanism — typically a high-speed grinding disc or hammer mill system — to repeatedly impact and friction-grind material down to a fine powder. The intense mechanical action generates significant heat, which is why many pulverisers include cooling or heat-management systems.

Key Characteristics

• Output size: Produces fine powder typically in the 20-80 mesh range, with specialty units capable of finer outputs.
• Heat sensitivity: The grinding process generates friction heat, so heat-sensitive resins may require cooling systems to prevent material degradation during processing.
• Higher energy demand: Grinding to fine powder typically requires 30-50% more energy per pound than granulating to coarse flakes, due to the additional mechanical work involved.

Side-by-Side Comparison

The table below summarizes the core differences between these two machine types across output, mechanism, and ideal use cases.

Common Applications for Each Machine Type

Granulator Applications

• Reprocessing injection molding runners and scrap parts into regrind
• Recycling extrusion trim and edge waste
• Preparing bulk plastic scrap (bottles, containers) for further processing

Pulveriser Applications

• Producing fine powder for rotational molding (rotomolding)
• Powder coating material preparation
• Specialty compounding applications requiring fine, uniform particle size

Using Both Machines Together: A Two-Stage Process

For operations that need fine powder output from bulky scrap material, the most efficient approach is typically a two-stage process: granulate first, then pulverise. Feeding bulky scrap directly into a pulveriser without pre-sizing can overload the grinding mechanism and significantly reduce throughput.

By granulating material into uniform 3-10mm flakes first, the subsequent pulverising stage operates more efficiently and produces a more consistent final powder, since the feed material is already a manageable, uniform size.

Key Factors to Consider Before Purchasing

Before selecting either machine type, evaluate the following:

1. Required output particle size: Confirm the exact mesh size or flake dimension your downstream process requires.
2. Material type: Heat-sensitive resins may require pulverisers with active cooling systems to prevent degradation.
3. Throughput needs: Match machine capacity (typically rated in lbs/hour) to your production volume.
4. Energy cost considerations: Factor in the higher ongoing energy demand of pulverising versus granulating when budgeting operating costs.

Final Recommendation

If your downstream process requires coarse flakes for reuse in injection molding or extrusion, a granulator is the appropriate and more energy-efficient choice. If your application — such as rotomolding or powder coating — requires fine powder, a pulveriser is necessary, and should ideally be fed pre-sized material from a granulator for optimal efficiency.

For operations processing bulky scrap into fine powder, investing in both machines as a two-stage system typically delivers more consistent output and higher overall throughput than relying on a single pulveriser alone.