Roller compactor is the equipment used in pharma for manufacturing of tablets, capsules and dry powder suspensions.
- This equipment is used for the manufacturing of those products which are sensitive to heat & moisture.
- Roller compactor is the equipment used in pharmaceutical industries for the dry granulation process.
- As the name indicates, a roller compactor consists of rollers which are used to compact the powders to form flakes, sheets or briquettes.
Principle of Roller compactor?
The roller compactor works on the principle of application of pressure by two counter-rotating wheels. The amount of pressure is controlled by the gap between two rotating wheels. When the amount of pressure is increased, the gap between rollers is decreased, and the thickness of flakes is decreased, and when pressure is reduced, the gap is increased and powder flakes with higher thickness are produced.
Roller compaction method
- The blend of active pharmaceutical ingredients and excipients is filled in a hopper and this powder blend from the hopper is supplied by a screw type feedering system to the rollers where it passes through two wheels or rollers which move in opposite directions.
- When the blend of powder passes through these two wheels, the pressure is applied over it, due to which the flakes of powder are formed.
- These flakes are broken down by using a cutting mill or oscillating granulator to obtain the granules of desired size.
- In some advanced types of roller compactors, the pneumatic suction system is applied to collect very fine powder particles and these are again passed through the rollers to obtain high quality granules with reduced concentration of fines.
- These sized granules are blended with lubricant and other excipients and are ready for compression or filling.
Why use a roller compactor?
For manufacturing of tablets, capsules and dry powder suspensions, we can also use a slugging process for heat and moisture sensitive products.
But when we use the slugging process, the flow issues are observed, due to which hardness and weight variation issues are observed during the process of slugging.
In roller compactor the uniform flow is ensured through screwed powder supply mechanism.
To ensure uniform hardness, the gap between two rollers is adjusted to control the thickness of powder flakes.
Benefits of roller compactor?
- The use of roller compactors enhances the flowability of granules.
- The roller compactor increases the bulk density of the product.
- The solvent is not required if we are using the roller compactor.
- The process of drying is also eliminated by the use of roller compactors in pharma.
- Powder flow is uniform as compared to the slugging.
- Roller compactor is used to compress herbal products very well, which have poor flow.
Pharma application of roller compactors
- In pharmaceutical industries, roller compactors can be used for manufacturing of immediate release tablets, sustained release tablets and effervescent tablets.
- Roller compactors in pharma are also used for high potent active pharmaceutical ingredients.
Types of roller compactors
Depending upon the roller pressure gap, the roller compactors are of two types
- Fixed Gap Roller compactor
- Floating Gap Roller Compactor
Fixed Gap Roller compactor
Fixed gap roller compactor means the gap between two rollers is not adjustable and both rollers are fixed.
Due to the fixed gap, if there is any change in material properties, then the amount of pressure will change and the produced powder ribbons will not be of uniform hardness.
Floating Gap Roller Compactor
Floating gap means the gap between the rollers can be adjusted.The gap can be increased or decreased depending upon the product nature, so equal pressure transmission is ensured inthe floating gap roller compactor.
Factor Affecting Roller Compaction
The main factors which may affect the process of formation of powder flakes during roller compaction are as follows,
- Diameter of roller
- Speed of roller
- Feeding system
- Material Nature
- Cutting mill speed
Diameter of roller
Higher pressure will be exerted by the rollers if they have a large diameter as compared to the rollers with a small diameter.
Speed of Roller
The contact between powder and rollers will be less if the speed of rollers is high and to exert more uniform pressure, the speed must be low to increase the contact time.
Feeding system
As the fine powders have poor flow so the feeding system must be screw type to ensure uniform and uninterrupted supply of product from hopper to rollers.
Material Nature
The amount of pressure required to compress the powders into flakes also depends on the nature of the materials.
Cutting mill speed
A fast cutting mill speed will result in the production of more fine so speed must be adjusted to ensure the production of good quality granules.
Parts of roller compactors
A roller compactor is divided into three main parts
- Feeding system
- Compaction system
- Cutting system
Feeding system
Feeding system consists of a hopper and screwed feeder to feed powder from hopper to the compaction unit.
Compaction system
Compaction unit is the part of roller compactors where the pressure is applied. This unit consists of two rollers which rotate in opposite directions.
Cutting system
Cutting system or size reduction unit consists of a cutting mill or oscillating granulator where a mesh is also installed to get the desired size granules.
Difference between wet granulation and roller compaction
In wet granulation, we always require a liquid solvent, and along with the liquid solvent, the application of heat is also required to remove the excessive moisture.
In the roller compaction method, there is no need for liquid solvent and only the pressure is applied by the rollers to compact the powders.
As there is no need for a liquid solvent, the heating process is also not required during roller compaction.
Conclusion
Roller compactor is used in pharmaceutical industries for manufacturing of moisture and heat sensitive oral solid dosage forms like tablets, capsules and dry powder suspensions.
The processing carried out by using roller compactor is known as roller compaction & in this process, powders are transformed into flakes by exerting the pressure with the help of two counter-rotating wheels or rollers.
The powder flakes are broken down into granules with the help of a cutting mill and then blended with the remaining excipients and again compressed by using a compression machine or filled in hard gelatin capsules or bottles in case of dry powder suspensions.
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