Variable And Fixed Gap 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.

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.

With floating gap (e.g. GERTEIS®-Machines) 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.