Dry granulation

How granules are formed in dry granulation?

Roller compaction or Slugging

Difference between roller compactor and slugging?

Dear @ Sajjad_Ahmad
Just trying to explain in brief

Granulation is a process in which powder particles are made to adhere to each other, resulting in larger, multi-particle entities, so called granules. If such a process is performed without adding liquids, this is called dry granulation. In dry granulation, the powder blend is compacted by applying a force onto the powder, which in general causes a considerable size enlargement.

If a tablet press is used for the compaction process, the term slugging is used. But since particles with a small particle size do not flow well into the die of a tablet press, the results are weight differences from one tablet (slug) to another. This in turn causes large fluctuations in the forces applied onto the individual slugs, with translates in variations of
the slug’s mechanical strength. Therefore, the properties of these granulates obtained by milling the slugs cannot be controlled well either. This is one of the main reasons why slugging is hardly used any more as a dry granulation method.

Roller Compactor:

A roller compactor generally consists of three major units.

1.A feeding system, which converts the powder to the compaction area between the rolls.

2.A compaction unit, where powder is compacted between two counter rotating rolls to a ribbon by applying a force.

3.A size reduction unit, for milling the ribbons to the desired particle size.


1. In general, a major advantage of dry granulation over wet granulation is the absence of water or any organic solvents. Therefore, this methodology is especially attractive for drugs, which are moisture or heat sensitive.

2. This is suitable for compounds that either have a low melting point or degrade rapidly during heating, as the method does not involve any drying step.

3. Roll compaction results in granules that form porous tablets thus allowing water to penetrate more easily into the tablet. This leads to improved disintegration behavior of tablets.

4. In addition, this process is environmentally friendly. Also the roll compaction technique provides an efficient and easily automated process

5. Low operational cost.

6. Dust problems are minimized or avoided and the die filling during tableting is improved.

7. The capping of tablets might also be reduced.

8. Roll compaction/dry granulation can be used, if the drug or the excipient is poorly flowing or sensitive to heat or moisture.

9. It can also be used for densification of powders prior to encapsulation.


1. One of the disadvantages of roll compaction is a phenomenon called ‘loss of reworkability’. Tablets made by roll compaction often show inferior tensile strength compared to tablets prepared by wet granulation or direct compaction. Minimum compaction force should be used, as well as a smaller particle size of starting powder.

2. A second disadvantage of roll compaction is the production of non‑compacted powder. Because no liquid binder is used, high amounts of fines remain and less product yield is obtained versus wet granulation.


  1. Peter Kleinebudde, Roll compaction/dry granulation: pharmaceutical applications, European Journal of Pharmaceutics and Biopharmaceutics 58 (2004) 317–326
  1. The Process and Applications of a Roll Compactor


  1. Basic Principles of Dry Granulation and Roller Compaction Technology
  1. Pros And Cons Of Roll Compaction


  1. Jeon I, Maurya B, Gilli T, Vandamme T, Fand Betz G. How to minimize the limitations of roll compaction, Pharm Technol Eur 2009; 21: 31-34.



as for as your point in disadvantages regarding non compacted is concerned,to overcome fine loss ,Pneumatic Dry Granulation ,technique is used which prevent the lose and give max yield

We do slugging still dont get expected amount granules. Why is reason behind that & how to solve it?

expected amount mean?<

most of the api & excipient remain in powder form( around 70-80%). After slugging, when milling those tablet for blending it happened

may need to revise formulation or revise hardness limit and screen size acc to dissoluton profile

In dry granulation, is there any kind of moisture allowing to present either api or excipient?

Mcc,strch ect hv its own moisture level but not the req of extra level

You said one of your comment that 10-20% powder should present in the granules. Is that including lubricating agent or not?

its minimum requirment.
including lubricant.
bcz if no fine void spaces will not b occupied