The increasing industrial demand for hard materials and their wide range of applications requires significant investigations to improve their machinability. Therefore, the current study addresses cutting forces and surface roughness during hard turning of AISI 52100 steel (59 hardness Rockwell C (HRC)) using ceramic tool. Turning experiments were held out by varying cutting speed, depth of cut, feed rate, and tool nose radius. For so doing, a central composite design (CCD) was adopted including 30 tests. Cutting forces and surface roughness were modeled using response surface methodology (RSM). The effects of each input parameter on output responses were investigated using analysis of variance (ANOVA) and response surface graphics. The findings of this study demonstrated that the force components were significantly influenced by depth of cut, followed by feed rate with a lower degree. Likewise, the negative result of the small undeformed chip thickness on surface roughness was reduced by the employment of large nose radius. Conclusively, a correlation between cutting force behavior and surface roughness was established and confirmed by the threedimensional topographic maps of the machined surfaces. The RSM was utilized to define the optimal machining parameters.

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The aim of this study is to evaluate the impact of factors such as cutting speed, feed rate, and depth of cut on surface roughness and Material Removed Rate (MRR) when machining in dry face milling AISI 1040 steel with coated carbide inserts GC1030 using the response surface methodology (RSM). For this purpose, a number of machining experiments based on statistical three-factor and three-level factorial experiment designs, completed (L27) with a statistical analysis of variance (ANOVA), were performed in order to develop mathematical models and to identify the significant factors of these technological parameters. Multi-objective optimization procedure for minimizing Ra, Ry and Rz and maximizing MRR using desirability approach has been also implementented. The current study was also carried out to investigate the tool life of the inserts. The models found the relationship between the cutting parameters (Vc, fz and ap) and the studied technological parameters. It has been found that the cutting speed was the most affecting surface roughness which is due to the geometry of the insert which has a scraping edge and enables to obtain low roughness even at important feed rate, followed by the feed rate and the depth of cut at the end. The optimal combination of cutting parameters were cutting speed of 314 m/min, feed rate of 0.16 mm/tooth and depth of cut of 0.6 mm with a composite desirability of 0.924.