Mathematical Modeling of the Bearing Ratio Curve Rmr (50% Rz), through Investigation of the Effect of Process Parameters in Hard Turning of Steel C55 (DIN) with Mixed Ceramics MC2 (Al2O3 + TiC)

The subject of modeling and predicting roughness parameters in hard machining has been discussed in many literature sources. However, most of these sources cover only the amplitude parameters such as Ra and Rz, leaving it unexplored to the right extent compared to its importance the roughness parameter bearing ratio curve (the Abbott–Firestone curve) which is essential in understanding the actual contact area of mating surfaces. To bridge this gap, this research has developed a mathematical model using the design of experiments method through investigation of the effect of process parameters in hard turning of Steel C55 (DIN) with mixed ceramics MC2 (Al2O3 + TiC). The model predicts the bearing ratio curve parameter Rmr (50% Rz), statistically processed using CADEX and Matlab. The research includes the ANOVA as a complementary tool in validating the generated mathematical model. The research analyzes the effects of material properties, cutting forces, and tool geometry as factors that affect the machining process. Additionally, it emphasizes the robustness of hard turning in consistently producing waviness patterns. Overall, this research provides valuable insights into the predictable effects of parameters on machined surfaces, which contributes to a better understanding of surface finish in metalworking.