The whole pressing process is proposed to be divided into three stages: compaction (pre-pressing); formation of a compact body; volumetric compression of the resulting compact body. At the first stage of pressing, under the influence of an external force, the material particles converge and seal due to their displacement relative to each other and filling voids. The forces overcome in this case are insignificant, the seal becomes noticeable even at low pressures. The applied energy is mainly spent on overcoming internal (between particles) and external (between particles and matrix machines) friction.