Grinding happens through utilizing different types of mills (hammer mill, nail mill, knife mill, etc.), the choice depending on the characteristics of the starting material and the use for which the ground material is intended.
As far as the processing of the dried medicinal plants, if one wants to obtain the herbal tea cut for preparing infusions and decoctions, it’s possible to use a knife mill adapted to the shredding of leaves, herbs, roots and bark (cortices).
Remember that in the case of hard and woody material, it’s not productive to subject it to extraction in the form that it is gathered (also in the case of one making a simple infusion).
It’s necessary to do a preventative shredding to reduce the dimensions to the appropriate granularity and allow the extractive solvent to arrive deep and completely extract the active ingredients.
Once the plant matter is shredded it must undergo sieving to eliminate traces of dust and granulated parts of the plant that aren’t homogenous.