Modelling and optimization of dimensional accuracy and surface roughness in dry turning of Inconel 625 alloy

The CNC dry turning of Inconel 625 alloy was investigated in this study. Turning was performed using different feeds, corner radii, and insert types. The dimensions and the arithmetic mean surface roughness were measured before and after turning. The influence of the input parameters and the process modelling were evaluated using a full factorial design of experiments. Prediction models were developed, and process optimization was carried out to simultaneously maximize dimensional accuracy and surface quality. The optimal values of the input parameters were identified for the wiper insert, a feed rate of 0.1 mm/rev, and a corner radius of 0.8 mm. Under these conditions, the optimal deviation from the specified dimension was 0.2 mm, while the surface roughness was 0.297 µm. During the confirmation phase, the mean percentage errors were 0.9 % for surface roughness and 3.45 % for dimensional deviation. The percentage errors observed in the confirmation experiments, all of which were below 5 %, demonstrate the feasibility of using the proposed approach for modelling and optimizing the turning of Inconel 625 alloy.