Experimental studies on cryogenic CO₂ face milling of Inconel 625 superalloy

ABSTRACT

In this study, face milling operation was carried out on an Inconel 625 superalloy. About 27 experiments (L₂₇) were conducted using Design of Experiments (DOE), which comprised three levels of cutting speed (V_c) and feed rate (f_z) with a constant cutting depth (a_p). The study included three coolant environmental conditions such as no coolant (dry), normal coolant (wet) and cryogenic CO₂ coolant. The output responses such as cutting temperature (T_s), cutting forces (F_x, F_y and F_z) and surface roughness (R_a) were observed during the experiments. The results were optimized using the TOPSIS technique with ANOVA tests. The optimization results of highest closeness coefficient (C_i) value indicated the lowest level of cryogenic CO₂ coolant environment and the input parameters were the cutting speed (V_c) 80 m/min and feed rate (f_z) 0.05 mm/tooth. The optimization results of the highest closeness coefficient (C_i) value were at cutting speed (V_c) 80 m/min, feed rate (f_z) 0.05 mm/tooth in cryogenic CO₂ coolant environment. The findings indicated that cryogenic CO₂ was both environmentally harmless and the best choice in comparison with dry and wet coolant.

KEYWORDS:

• Inconel 625
• face milling
• temperature
• cutting forces
• surface roughness
• SEM
• optimization

Acknowledgments

The authors would like to thank Dr T. Sundararajan, Professor, Department of Mechanical Engineering, IIT Madras, Chennai, for providing the experimental facilities.