What is a Ring Die Pellet Mill? Applications and Benefits Explained

Amy     06/17/2025

What is a Ring Die Pellet Mill?

A ring die pellet mill is a large-scale industrial machine used to convert powdered or fibrous materials (like wood chips, sawdust, straw, biomass, animal feed) into compact cylindrical pellets. Inside, a ring-shaped die with multiple holes is fitted with rollers. The raw material is fed into the die and compressed through the holes, forming consistent pellets that are then cut to length.

Applications

Ring die pellet mills are widely used in:

  • Biomass energy production: Produce wood pellets for heating, power generation, and industrial fuel.

  • Feed industry: Manufacture livestock and aquaculture feed pellets.

  • Waste recycling: Compress agricultural or forestry by-products (like straw, husks) into pellets.

  • Pharmaceuticals & specialty powders: Produce pelletized forms for controlled-release products.

How It Works?

  • Raw material prep: Materials are dried and milled to appropriate moisture and granularity .

  • Feeding & compression: Material enters the inside of the ring die; rollers force it through holes.

  • Pellet formation: Pressure and friction activate natural binders like lignin to form solid pellets.

  • Cutting & cooling: External cutters cut pellets to set length; then cooled and screened

Benefits

  • High capacity & efficiency: Ideal for large-scale industrial production, yields include 1–2.5 t/h per machine, up to 40 t/h in full setups.

  • High pellet density & quality: Delivers dense, smooth pellets with fewer fines.

  • Durability & low energy consumption: Ring dies survive longer and use less energy compared to flat die models.

  • Versatility: Can process wood, straw, husk, palm fiber, and feed materials.

  • Customizable: Dies come in various materials and thicknesses to suit corrosive or abrasive raw materials .

Feature Flat Die Ring Die Vertical Ring Die Horizontal Ring Die
Structure Simple design Complex design Vertical orientation Horizontal orientation
Capacity Low (small-scale) High Moderate to high High
Lifespan Shorter Long Long Long
Efficiency Lower High Very high (~99% yield) High (variable length)
Speed - - Lower RPM Higher speed
Material Suitability General materials General materials Fibrous materials (straw) Sticky/wet materials
Maintenance Easy Moderate Easier access Easier cleaning

Key Notes:

  • Flat Die: Best for small farms and budget operations
  • Ring Die: Ideal for industrial-scale pellet production
  • Vertical: Superior for low-density biomass materials
  • Horizontal: Faster processing but may require length calibration

Take Action

If you’re planning to start pellet production, consider: