Granulation combines smaller powder particles into larger, more uniform granules, improving flow properties, reducing dust, and often making downstream processing such as filling easier and more consistent. Two main approaches exist - wet and dry granulation - suited to different materials. This page explains both.
Key points
- Wet granulation adds a liquid binder to form granules, suited to materials that aren't moisture-sensitive.
- Dry granulation uses mechanical compression instead, suited to moisture or heat-sensitive materials.
- Granule sizing after formation typically uses milling and sieving to achieve a uniform particle size distribution.
- Granulation generally improves flow and reduces dust compared with the original ungranulated powder.
Wet Granulation
In wet granulation, a granulating liquid - commonly water, ethanol or isopropanol, alone or in combination - is added to a powder bed under the influence of an impeller, screws, or air, causing particles to bind together into granules. This method generally offers better uniformity and compressibility, and suits ingredients that aren't sensitive to moisture and heat.
Dry Granulation
Dry granulation forms granules without any liquid, instead using mechanical compression to bind smaller particles into larger ones - typically using a roll compactor or similar equipment. This method suits materials that are moisture or heat-sensitive, since it avoids the drying step that wet granulation requires, and generally offers a simpler process with shorter production times.
Suitable Materials and Products
Granulation suits powder products where flow properties, dust reduction, or downstream processing consistency matter - see powder blending and filling and packing. Product moisture and heat sensitivity is the main factor determining whether wet or dry granulation is appropriate.
Equipment and Technical Considerations
Wet granulation commonly uses high-shear mixers, twin-screw granulators or fluidised bed equipment, followed by a drying step to remove the added liquid - see drying. Dry granulation uses roll compactors or similar equipment to densify powders under pressure. After either method, granule sizing typically uses milling and sieving to achieve a uniform final particle size distribution.
Batch Sizes and Production Scale
Granulation batch sizes are set by equipment capacity, and manufacturers should be able to confirm expected throughput for a specific granulation method and target granule size.
Quality and Regulatory Considerations
Granule size distribution, flow properties and, for wet granulation, residual moisture content are typical quality measures, tested against agreed specifications - see setting quality specifications.
Why Build Particles Up
Granulation is the reverse of milling - building fine powder into larger, more uniform granules. The reasons are practical rather than chemical. Granules flow better than powders, which improves handling and filling accuracy. They generate far less dust, reducing both exposure and explosion risk. They segregate less during handling, so a blend stays uniform. And they dissolve or disperse more predictably in use.
For products supplied to end users who will dose or dilute them, these are significant benefits, which is why granular forms are common in agrochemicals, detergents and water treatment products.
Methods and Control
Granulation may be wet, using a liquid binder followed by drying, or dry, using compaction. Wet granulation generally gives better control of granule properties but adds a drying step with its own cost and heat exposure; dry granulation avoids that but suits fewer materials.
Granule size distribution, strength and dissolution behaviour are the properties to specify. Granules that are too fragile break down during handling and reintroduce the dust problem granulation was meant to solve, while granules that are too hard may not disperse properly in use - so strength is a genuine specification parameter rather than an assumed property.
Questions to Ask a Manufacturer
- Which granulation method do you recommend for our material's moisture and heat sensitivity?
- What equipment do you use, and what granule size range can you achieve?
- For wet granulation, how do you control residual moisture content?
- What sizing and sieving steps follow granulation?
Related Manufacturing Capabilities
Frequently Asked Questions
Is wet or dry granulation cheaper?
Dry granulation generally has a simpler process and shorter production time since it avoids a drying step, but the right method depends on your material's properties, not cost alone.
Can granulation improve a product that currently has poor flow properties?
Often yes - granulation is commonly used specifically to address poor powder flow, dust generation, or segregation issues in an existing formulation.
Does granulation change the chemical composition of the product?
No - granulation is a physical process that changes particle structure and size, not the underlying chemical composition of the ingredients.
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Search the DirectoryLast reviewed: August 2026. Regulation and guidance change — verify anything you rely on against the primary source. Tell us if something here is out of date.