In this paper we present a method of determination of the static and dynamic friction coefficients values for the milling products and we study how these depend of the kinematic parameters of the sieve motion. The determination of the static friction coefficient was made using the inclined plane method, while the dynamic friction coefficient is based on the determination of the resistant mechanical work consumed to overcome the frictions. The determined friction coefficients have general aspect, due to the fact that the materials motion on the working surface is very complex: slipping, rolling, sliding etc.
