Choosing a roller compactor for pharma

 What is Roller Compactor in pharma?

A roller compactor is pharmaceutical machinery used for tablet manufacturing, as well as powdered fillings for sachets and capsules. The purpose of these machines is to agglomerate the powders containing active ingredients and excipients to form uniformly sized granules. This entails subjecting the powder to precisely metered crushing and grinding forces between rotating rollers.

Choosing the right roller compactor is a matter of matching its features and engineering to target application and individual needs.

Principle:

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.

Pharma Roller Compactor applications

Traditionally, dry granulation in tablet manufacturing was performed by ’slugging’ – feeding the blended granules direct into a tablet press, to be crushed and compacted under pressure in a forming die. The main issues with slugging are that fine particles do not flow well into the die, leading to unacceptable variations in tablet form and cohesion. Consequently, roller compaction has largely replaced slugging in dry granulation.

The roller compaction process usually involves feeding various sized particles of active ingredient plus excipients like lactose or cellulose between two textured press rollers that then produce a compacted powder called ‘ribbons, ‘flakes’ or ‘briquettes’. These can then be further milled to a uniform and cohesive powder, ready for final tablet manufacturing.

Use of laboratory roller compactors in formulation development, helps to overcome challenges of inconsistent bulk properties and fine powder characteristics to adapt substances to tableting or fillings.

Use of a roller compactor allows for higher performance manufacturing of capsules and tablets. Roller compaction improves the bulk density of the processed powders significantly.

Primary considerations when purchasing a granulation pharma compactor are its total costs of ownership (TCO), ease of cleaning, suitability for high containment manufacturing and suitability for processing target substances and ingredients. The latter consideration will be impacted by roller design.

As with any pharmaceutical equipment, there are operational challenges when using a roller compactor as granulation equipment. These include overcoming loss of recompactability (with effects on tensile strength) and formation of non-compounded powder residues in dry granulation.

Types of Roller Compactors:

Roller compactors can be divided into two categories: one is equipped with a fixed gap, the other one with a floating gap. Both consist of the three major units as explained above but differ in the way in which the smallest distance (gap) between the rolls is realized.

1. When a fixed gap is installed, the amount of powder drawn in into the compaction area between the rolls is inconsistent, which results in different forces applied to the powder bed. Like in slugging, this will cause large fluctuations in the ribbon and granulate properties.

2. In floating gap the distance between the rolls change according to the amount of powder provided. The force applied to the powder remains constant. This ensures that property fluctuations in the granules are reduced to a minimum.