Comparison between mixed ceramic and reinforced ceramic tools in terms of cutting force components modelling and optimization when machining hardened steel AISI 4140 (60 HRC)

This paper describes a comparison between mixed ceramic [Al2O3 (70%) + TiC (30%)] and reinforced ceramic [Al2O3 (75%) + SiC (25%)] tools in terms of cutting force components when machining in dry hard turning AISI 4140 steel, hardened to 60 HRC. The response surface methodology (RSM) and the analysis of variance (ANOVA) are applied to investigate effects of cutting speed, feed rate and depth of cut on cutting force components in order to model and optimize these technological parameters. Results of this study indicate that the machining with the mixed ceramic insert generates lower values of cutting force components than reinforced ceramic insert. Consequently, the mixed ceramic CC650 is the most powerful tool. The developed models can be used in the metal machining industries and would be helpful in selecting cutting variables for optimization of hard cutting process

Machinability analysis of dry drilling of carbon/epoxy composites: cases of exit delamination and cylindricity error

International audienceThe aim of this work is to define the cutting conditions that allow the dry drilling of carbon fiber reinforced epoxy (CFRE) composite materials taking into consideration the quality of the drilled holes (the exit delamination factor and the cylindricity error) and the optimum combination of drilling parameters. A further aim is to use grey relational analysis to improve the quality of the drilled holes. The machining parameters were measured according to 3(3) full factorial parameter designs (27 experiments with independent process variables). The experiments were carried out under various cutting parameters with different spindle speeds and feed rates. Drilling tests were done using WC carbide, high-speed steel (HSS), and TiN-coated carbide drills. The experiment design was accomplished by application of the statistical analysis of variance (ANOVA). Results show that the thrust force is mainly influenced by the tool materials and the feed rate, which has a strong influence on the exit delamination factor. On the other hand, the spindle speed particularly affects the cylindricity error of the holes. Correlations were established between spindle speed/feed rate and the various machining parameters so as to optimize cutting conditions. These correlations were found by quadratic regression using response surface methodology (RSM). Finally, tests were carried out to check the concordance of experimental results