dry granulation

Dry granulation makes granules by squeezing the powder hard enough that it clumps on its own — no water, no drying. Imagine pressing dry flour into a packed cake and then breaking that cake into crumbs: the crumbs flow and behave better than the original loose flour.

There are two common ways to do it. In slugging, the blend is compressed into large rough tablets (slugs) and then milled back into granules. In roller compaction, the powder is squeezed between two counter-rotating rollers into a dense ribbon that is then broken and screened. Either way you get denser, free-flowing granules ready for blending and tableting, all without ever adding liquid.

Because it skips water and heat, dry granulation is ideal for moisture- or heat-sensitive drugs. The trade-offs are that not every powder compacts well dry, the equipment can generate fines and dust, and re-compressing material twice can sometimes reduce its later tablet strength.