Abstract :
Theoretical model of surface roughness forming, factors and parameters that describe the surface geometrical state as well as the disturbances in real surface after machining were presented. The usefulness of chaotic attractors, Lapunovʹs exponent and fractal dimensions was evaluated in order to assess the geometrical structure of surface after machining. Chaotic attractors and Lapunovʹs exponents were recognized to be useless for evaluating the surface geometrical structure; however, of many definitions of fractal dimensions the box dimension was considered to be most useful. Experiments were carried out in lathe. Three materials with different properties and metallographic structures, i.e., steel for treatment C55E, gray cast iron EN-GJL-150 and brass CuZn40Pb2, were turned. The measurements of the of surface geometrical structure were carried out on the Rank Taylor Hobson roughness meter model Form Talysurf 120L. For all three materials the fractal dimension was measured as a function of machining parameters, i.e., feed and cutting speed. Moreover, the correlation between the values of fractal dimensions and roughness parameters Ra and Rku for 2D and Sa and Sku for 3D measurements were analysed. Also comparative analysis of fractal dimension values for all there materials was made. Cognitive and utilitarian conclusions as well as further directions of investigations were given.
