POSTULATED MODELS FOR THE FRACTAL DIMENSION OF TURNED METAL SURFACES

Fractal geometry has been introduced to describe the roughness of machined surfaces for providing evaluation by one or two parameters. The present contribution is aimed at modelling the interactions of cutting conditions with fractal dimension of surfaces obtained by turning using analysis of variance (ANOVA) and response surface methodology. Also, single interactions were studied through single regression analysis. Four metallic materials were used namely, Ck60 plain carbon steel, 304 stainless steel, 6061 aluminum alloy and a brass. Longitudinal turning was performed with constant depth of cut, and feed and cutting speed varied over a wide range of values applied in roughing, semi-finishing and finishing. In relation to the fractal dimension D, the skewness of the profile distribution R-sk was considered in view of bearing properties of the surfaces. The predictive statistical models developed on D for all four materials considered with respect to feed and cutting speed showed fair to good correlation. Single regression models of D against feed exhibited very good correlation. Further, the findings of the present study were compared to results existing in literature and partial relevance was proved.