Multi-objective optimization of cutting parameters for finishing end milling Hardox® 450

Abstract

Hardox® 450 is pre-hardened structural steel with high hardness and mechanical strength, designed to resist under abrasion wear, cracks, and breakages. This material provides a longer service life for crushers, buckets, and gears due to its excellent mechanical properties, which result in low machinability. Moreover, the knowledge about machining this material is limited, justifying further investigation. Thus, this study aims to evaluate the influence of cutting speed (vc), axial depth of cut (ap), and feed per tooth (fz) on the machining forces and surface finish during the finishing end milling of Hardox® 450 with a CVD-coated carbide tool. The experiment was planned and analyzed through a 3-factor, 3-level Box-Behnken Design. The analysis of variance showed that ap was the most significant parameter for all response variables considered in this study. A multiobjective optimization was carried out to determine the ideal levels of cutting parameters, considering the lowest values of static and dynamic machining forces and average and total surface roughnesses. The model suggests that the best results are achieved with vc = 89 m/min, fz = 0.1 mm/tooth, and ap = 0.212 mm. Even with efficient results, the predicted and measured response variables differed slightly (mainly due to tool wear).