Study of the Cutting Parameters on Surface Roughness and Material Removal Rate in Hard Turning of UHMWPE

The surface finish of industrial components has an important role in their performance and lifetime. Therefore, it is crucial to find the cutting parameters that provide the best surface finish. In this work, an experimental study of the effect of cutting parameters on ultra-high molecular weight polyethylene (UHMWPE) by hard turning process was carried out. Today, the UHMWPE polymer continues to find applications mainly in the automotive industry and biomechanics due it is resistant to wear, impact and corrosive materials. A face-centered Central Composite Design (CCD) and Response Surface Methodology (MSR) were applied to evaluate the influence of the speed (V_c), feed (f) and depth of cut (a_p) of the hard turning operation on the Average Surface Roughness (R_a) and Material Removal Rate (MRR). The results allowed obtaining adjusted multivariable regression models that describe the behavior of the Ra and MRR that depending on the cutting parameters in the hard turning process. The predictive models of Ra and MRR showed that they fit well with correlation coefficients (R²) around 0.9683 and 0.9680 to the experimental data for R_a and MRR, respectively. The ANOVA results for R_a showed that the feed is the most significant factor with a contribution of 42.3 % for the term f ², while the speed and depth of cut do not affect R_a with contributions of 0.19% y 0.18%, respectively. A reduction of feed from 0.30 to 0.18 mm·rev^-1 produces a decrease in surface roughness from 6.68 to 3.81 µm. However, if the feed continued to reduce an increase in surface roughness occurs, a feed of 0.05 mm·rev^-1 induces a surface roughness of 14.93 µm. Feeds less than 0.18 mm·rev^-1 causes heat generation during hard turning increasing the temperature in the process zone, producing surface roughness damage of the UHMWPE polymer. Also, the ANOVA results for MRR demonstrated that all of the cutting parameters are significant with contributions of 31.4 %, 27.4 % and 15.4 % to feed, speed and depth of cut, respectively. The desirability function allowed optimizing the cutting parameters (V_c = 250 m·min^-1, a_p = 1.5 mm y f = 0.27 mm·rev^-1) in order to obtain a minimum surface roughness (R_a = 4.3 µm) with a maximum material removal rate (MRR = 97.1 cm³·min^-1). Finally, the predictive models of Ra and MRR can be used in the industry to obtain predictions on the experimental range analyzed, reducing the surface roughness and the manufacturing time of UHMWPE cylindrical components.