Dry granulators effectively prevent moisture absorption and caking of materials while rapidly and efficiently completing the granulation process. They serve as essential granulation equipment widely used in pharmaceutical, food, and other industries.
This guide will provide detailed information about dry granulation machines including their advantages, working principles, components, and more, to help you more easily select equipment.
What is a Dry Granulator?
A dry granulator compacts powder into granules without adding liquid binders. It mechanically compresses powder into dense pellets, which are then crushed by a granulation system into particles of the desired size. This machine is particularly suitable for moisture-sensitive or heat-sensitive raw materials.
Advantages of Dry Granulators
Production versatility
By adjusting the roller gap and the granule sieve specifications, you can rapidly switch between different particle size specifications from 0.5 to 5 mm without complex changeovers. This can significantly enhance your production flexibility.
Continuous Processing
The dry roller compaction process supports continuous production mode, delivering higher efficiency than batch granulation and meeting your demands for high-volume manufacturing.
Strong Raw Material Protection
The whole granulation process avoids solvents or thermal treatment to prevent degradation of active ingredients. It is highly suitable for processing heat-sensitive, moisture-sensitive, and highly active raw materials.
Superior Particle Quality
Dry granulation provides uniform particle density (bulk density variation ≤5%) and controllable hardness, with tablet weight precision of ±1.5%—exceeding wet granulation’s ±2%. This ensures more consistent finished product weight and appearance during subsequent tableting or capsule filling.
No drying step required
The dry granulators have no need for liquid binders, which avoids instability caused by added water or solvents. For moisture-sensitive or hygroscopic materials, you can directly obtain granules ready for tableting or filling, significantly reducing energy consumption and process time.
Compact Footprint
The equipment adopts a compact overall design and is suitable for installation in production environments with limited space.
Energy saving
The entire granulation process requires no heating or drying. This means it saves energy compared to traditional wet granulation while lowering equipment operating and maintenance costs.
Enhanced Flowability
Dry-granulated pellets exhibit uniform particle size and regular morphology, significantly improving flowability compared to raw powders. This enhances operational stability in downstream equipment such as tablet presses and filling machines.
Supports Enclosed Granulation
For highly active or high-risk materials, the equipment can be paired with an optional fully enclosed system and negative pressure dust collection structure. This effectively prevents dust escape, ensures operator safety and maintains a clean production environment at the same time.
Working Principle of Dry Granulator
Preparation
Mix the powder with excipients to keep uniform distribution of material components. Then, steadily conveys the material by the feeding system to the granulator’s compression rollers. To prevent bridging or blockages, some models are paired with forced feeders or vibrating feed systems to ensure continuous and even powder flow into the tableting station.
Pellet Formation
Roll Compaction
The machine feeds the powder between a pair of counter-rotating rollers. Under high pressure, the powder is compacted into dense pellets or blocks.
By adjusting the roller gap, roll speed, and applied pressure, it can flexibly control pellet thickness and density to satisfy your different hardness and bulk density requirements.
Dry Compaction
High-tonnage press wheels directly compress powder into larger dry blocks (over 25mm diameter, 10–15mm thickness). This simpler method is particularly suitable for pilot-scale validation and small-batch process scale-up.
Crushing
The granulator (or crushing unit) crushes compacted sheets or blocks into granules by hammer mill or other machines.
Screening
The granules then enter a vibro sifter machine to remove oversized or undersized powder to ensure consistency in particle size, density, and flowability of the final product. Qualified granules are typically used in subsequent processes such as tableting, capsule filling, coating, or fluid bed granulation.
Types of Dry Granulators
Roll Compaction Dry Granulator
The roll compaction dry granulator adopts a 316L stainless steel roll compaction structure and it offers robust compaction capability and superior corrosion resistance to withstand continuous high-pressure operation over extended periods. It produces 10–2000 kg of granules per hour which can meet large-scale continuous production demands in pharmaceutical, chemical, and food industries.
Some premium models further incorporate hydraulic pressure closed-loop control, online sampling inspection, and automatic cleaning (CIP or SIP) functions, helping you to achieve higher production traceability and quality consistency.
Heavy Duty Dry Granulator
The heavy duty dry granulator employs a compaction principle similar to a single-punch tablet press machine. It uses a “punch die + pressure wheel” mechanism to compress powder into large “dry tablets” (10–50 mm diameter), and then crushed and rounded into granules. It is capable of producing 5–50 kg per hour at pressures ranging from 30–50 MPa, particularly suited for processing high-hardness, low-flowability, or highly reactive materials.
Its compact design with minimal footprint makes it ideal for laboratory, pilot-scale, or small-batch custom production applications.
Components of The Dry Granulator
Hopper
The hopper temporarily stores powdered material awaiting compaction. You can select from various capacity specifications based on production requirements. If the powder is prone to caking, a bin blender is recommended.
Feeding System
The feeding system controls material flow rate to ensure consistent filling for each compression cycle. It is always using variable frequency drives or servo-controlled feeding systems which can automatically adjust rotational speed based on powder characteristics such as bulk density, particle size distribution, friction coefficient to achieve superior compaction uniformity.
Crushing Blade Assembly
The blades are made from high-speed steel (HSS) or tungsten carbide coating, demonstrating exceptional wear resistance and cutting precision. It shatters the blank into coarse particles ranging from 2 to 10 mm, typically arranged in a spiral configuration.
Screen System
The screening system is used to classify crushed particles. It removes excessively fine or coarse fractions to ensure uniformity in the final product’s particle size.
You can select the appropriate mesh size (typically 0.5–5 mm) based on different product processing requirements.
Control System
The entire machine usually adopts a PLC-based automatic control system with a human-machine interface (HMI). This makes you better at setting in real time and monitoring critical process parameters such as roller pressure, roller speed, feed rate, and particle size.
Dust Collection System
Certain models can be equipped with an independent dust collection system to recover fine powder generated during granulation. It can reduce waste and prevent cross-contamination.
If your production involves highly active or toxic materials, it is recommended selecting a negative-pressure sealed dust collection structure or HEPA filtration system. This protects the operating environment while ensuring product purity and operational safety.
Clean in Place System
In pharmaceutical or high-cleanliness production environments, you can optionally integrate a CIP (Clean-In-Place) system which realizes automated cleaning of the compression rollers, feed screw, and crushing chamber.
Applications for Dry Granulator
In the pharmaceutical industry, dry granulators are particularly suitable for preparing granules of moisture-sensitive, heat-sensitive, or easily degradable drugs, such as vitamins, analgesics, antibiotics, and various active pharmaceutical ingredients (APIs).
In the food industry, dry granulators are commonly used to produce nutritional supplements, functional food additives, instant beverage granules, and similar products. The precise particle size control brings uniform granule appearance, excellent flowability, and stable dissolution rates for you.
In addition, dry granulators achieve high-density particle compaction in industries including chemicals, ceramic powders, battery materials, and catalyst carriers.
Considerations for Dry Granulator
Material Type
Please make sure the granulator is compatible with your material. If your powder is poor flowability, weak compressibility, or high oil content, it may be challenging to form stable pellets during roller compaction. You can take additives or pretreatment (like dry blending or modification) to improve this. So it is advisable to conduct small-scale trials before finalizing your selection.
Particle Size
Dry granulators can meet different product particle size requirements by adjusting roller gap and sizing screen specifications. If you need frequent changes to the product line, select models with quick-change screen structures to minimize changeover time and enhance production flexibility.
Production Capacity
Equipment capacity must precisely match your production schedule. For large-scale continuous production, roller-compaction models ensure stable output under prolonged, high-load conditions. To guarantee continuous operational reliability, opt for models with independent cooling systems and automatic lubrication devices for extending equipment lifespan and reducing maintenance frequency.
Convenience
To minimize downtime, prioritize models featuring modular quick-release designs and CIP (Clean-in-Place) functionality. This configuration enables rapid material changeovers and thorough cleaning, significantly improving your batch transition efficiency while maintaining hygiene standards.
Conclusion
Dry granulators offer a highly efficient and reliable solution for pelletization, enabling granulation without water or solvents to ensure consistent product quality. When selecting equipment, we recommend prioritizing compatibility between the machine and your materials, ease of cleaning, and the supplier’s technical support to guarantee long-term stable operation and high-quality output. If you require customized dry granulation solutions, please contact us to receive professional recommendations.
FAQ
Can the equipment be expanded if future production capacity demands increase?
Some dry granulators support modular expansion, such as increasing drive power, widening the compression rollers to enhance line speed and production capacity.
If you have clear expansion plans during the initial selection phase, please tell us in advance so we can recommend models that facilitate future upgrades.
What technical support and services are provided?
We offer one-stop services from project proposals, equipment selection, and layout design to installation and commissioning.
All equipment complies with cGMP and CE requirements, and we provide process validation and GMP validation support tailored to your specific process flow.
Does the dry granulator support aseptic production?
We offer models meeting aseptic requirements.
All material-contact components utilize sterile-grade polished stainless steel and support SIP functionality. Its sealed design effectively prevents microbial contamination which meets stringent requirements for aseptic API and high-end pharmaceutical production.
What is the replacement cycle for the “compression rollers” and “granulation sieves”?
Their service life primarily depends on material characteristics and operating intensity.
Compression rollers made of highly wear-resistant materials can operate continuously for thousands of hours under normal conditions. Sieves are considered wear parts, so it is advised for you to do regular inspection and replacement based on production frequency and maintenance schedules to ensure consistent particle quality and equipment stability.
