When the external mechanical force is applied to the dye aggregates, if the mechanical force is greater than the attraction between the dye aggregates, the dye aggregates will be destroyed, thus dispersing into primary particles. Dyes need to consume energy in the dispersion process, and the sanding process of a sanding mill is the process of providing energy to dye aggregates. The dye can be sanded by a process of collision, extrusion or shearing between the dye aggregates and the medium. The general sanding medium is glass beads.

Under the action of mechanical force, the interaction between medium and dye aggregation, makes some aggregate divided and broken, but there are a large part of the aggregate only produces a tiny crack, hours after mechanical force when the outside world, the small crack in molecular inter-atomic forces and aggregate surface under the action of surplus value chain heal on its own. Therefore, it is necessary to constantly apply mechanical forces to the dye aggregates to gradually break up the cracked aggregates. If the dye dispersant is added to the grinding system, the dye dispersant particles will tip into the cracks of the dye aggregate under the wetting and adsorption action of the dye dispersant, so as to prevent the self-healing of these cracks, so as to achieve the purpose of dispersion.