Evaluation of trade-off between cutting time and surface roughness robustness regarding tool wear in hard turning finishing

This study proposes a robust optimization strategy to analyze the trade-off between the conflicting objectives of minimizing the cutting time and the distance between the actual value of the mean and total roughness of their respective targets, along with the variation caused by flank wear. The motivation for this work is that the effect of tool wear is often neglected by traditional roughness optimization approaches in hard turning. The wear evolution causes an unwanted variation in roughness, compromising the process's ability to meet specifications and leading to the underutilization of cutting tools. The methodologies used were as follows: robust parameter design, response surface methodology, combined array, multivariate mean square error, and normal boundary intersection. Cutting speed, feed rate, and depth of cut were the process factors considered. An experimental study was performed to demonstrate the strategy effectiveness for the dry finishing turning of AISI 52,100 hardened steel. The results showed that the effect of flank wear was statistically significant for both roughness. The lowest roughness values with maximum robustness are achieved at the expense of higher cutting times. As the process must be flexible to meet different specifications, the proposed strategy allows exploring other solutions that ensure that the machined parts throughout the tool life meet a roughness specification in the shortest possible cutting time. This decision-making support is the novelty and advantage of the proposed strategy. These solutions prevent the production of non-conforming parts and the underutilization of cutting tools and improve process productivity.