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Dry Granulation: Industrial Overview & Calculator

Flow consistency is critical for high-speed manufacturing, particularly in pharmaceutical tabletting and plastic injection molding. Dry granulation is a mechanical process used to increase the particle size of bulk solids without the need for liquid binders, significantly improving flowability and preventing segregation.

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1. What is Dry Granulation?

In dry granulation, the particle size of a bulk solid is increased through mechanical compaction. This is achieved using a roller press or roll compactor which forces powder between two counter-rotating rolls under high pressure.

The core physics relies on the throughput equation:

\[ \dot{m} = W \cdot G \cdot v \cdot \rho_{flake} \]

Where:

• \(\dot{m}\) = Mass flow rate
• \(W\) = Roll width
• \(G\) = Roll gap
• \(v\) = Peripheral velocity (\(\pi \cdot D \cdot N\))
• \(\rho_{flake}\) = Density of the compacted ribbon

2. Industrial Applications

• Pharmaceuticals: Reducing segregation of APIs and enhancing flow to high-speed tablet presses.
• Plastics: Consolidating fine additives or recycled powders to ensure consistent dosing in extruders.
• Chemicals: Managing dusty materials to improve safety and handling efficiency.

2.1 Dry Granulation in Pharma

Dry granulation is favored for materials that are sensitive to moisture (eliminating the need for aqueous binders) or heat (eliminating the drying step). By creating granules of controlled size and strength, engineers ensure uniform distribution of the Active Pharmaceutical Ingredient (API) during tabletting.

2.2 Plastic Industry Efficiency

In plastics manufacturing, maintaining a reliable flow of material to molds is critical. Dry granulation prevents issues like bridging or erratic flow in feed hoppers, especially for low-density powders or recycled regrind.