Theory of Comminution or Size Reduction

A flaw in a particle is any structural weakness that may develop into a crack under strain. The Griffith theory (4) of cracks and flaws assumes that all solids contain flaws and microscopic cracks, which increase as the applied force increases, according to the crack length and focus of the stress at the crack apex. 

A granule or particle may be subjected to one or more of the following four forces during milling  

Impaction (the direct, high-velocity collision force) 

Tension (the force that works to elongate or pull a particle apart) 

The mechanism by which sizing of dried granules occurs is similar to that of crystalline materials. Cleavage occurs at the weakest point or points in the granule 

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There are no published studies describing compactormilling studies. The theory of comminution or size reduction is well written about by Rekhi and Vuppala. They described the criteria for mill selection, mill classification, and variables affecting the sizing process and scale-up. The interested reader is also recommended to peruse Parrot, Johnson, and Lantz. ... 

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