The application of cylindrical perforated sifting surfaces with volumetric riffles in vibrocentrifugal machines for separation of loose materials requires the development of methodologies for studying the dynamics of particles in working zones and ensuring structural reliability. The analogy with hydrodynamic models became the basis for mathematical modeling of the movement of loose materials along the sifting surface. The movement of loose material was considered as the movement of a pseudo-liquid medium, which has characteristic parameters such as viscosity, density, porosity, and layer height. The use of volumetric riffle-activators on a perforated sifting surface intensifies the processes of loose medium separating, however, it requires studying their dynamics and reliability of structures. The obtained mathematical expressions for the velocity and flow rate of the medium take into account the design and kinematic parameters of sifting surface, riffle-activators and properties of loose material. To test the obtained mathematical expressions, studies were conducted on sifting surfaces with rectangular holes with riffles of various shapes and sizes. The study also analysed the degree of properties influence of loose materials, using corn and sunflower seed mixtures as an example, on their dynamic indicators. The dynamics of loose medium on cylindrical perforated surfaces with riffle-activators is one of the main tasks for calculating the productivity and quality of the sieve separation process. Obtained appropriate dependencies of technological indicators of perforated vibrating surfaces allowed to establish ranges of variation of their rational ranges of design parameters, including the parameters of riffle-activators. The natural frequencies and shapes have been determined on the basis of numerical and experimental methods, which make it possible to assess the possibility of resonant modes during the operation of cylindrical sifting surfaces. Oscillations depending on its structural and kinematic parameters and properties of loose materials have been studied, which will ensure the reliability and technological durability of the structure of riffled sifting surfaces.