To design assembly automates for pressed parts the capacity of power needed for pressing-in shall be defined. Reserve of pressing power is necessary to provide the assembly of details with interference fit by pressing. The current method for calculation of the pressed part interference fit is not accurate enough considering that cylindrical details are a dimensional object; therefore, roughness parameters corresponding to real surface shall be defined. The demand for a more precise calculation method is facilitated by development and progress of mechanical engineering, which asks for more and more accurate equipment and resistant parts with high durability.