Optimization of process parameters in turning operation using CNT based minimum quantity lubrication (MQL)

Abstract

Smart and modern machining process is a key success parameter in process economics. Various machining methodologies have proven success in their respective verticals, but they possess certain limitations such as power loss, voluminous coolant, effective disposal of used coolants/oils, detrimental chip hazards to workers etc. earlier one factor at a time (OFAT) approach was implemented to overcome these limitations, but later these limitations were taken over by chemometric approaches such as Taguchi method, Response surface methodology (RSM) such as Central Composite Design (CCD) and Box-Benkhen design (BBD) and Doehlert’s design. In our study, three process variables such as carbon nanotubes (CNT) concentration (%), pressure (bar) and flow rate (ml/hr) were selected and experiment was conducted based on 15 run Box-Benkhen design, to optimize the effect of CNT on minimum quantity lubrication towards its effectiveness on machining of EN24 Alloy steel. At desirability factor of 1, a projected cutting force response of 218.28 (kgf) was obtained using CNT concentration (0.79 mg/L), pressure (6 bar), and flow rate (158.586 ml/hr) (kgf). Likewise, with a desirability factor of 1, the optimal anticipated conditions giving CNT concentration (0.828 mg/L), pressure (6 bar), and flow rate (135.354 ml/hr) yielded a projected surface roughness response of 3.3969 (μm). The experimental values were determined to be 211.32 (kgf) and 3.362 (μm) at the predicted conditions. At the expected ideal conditions, the experimental value was found to be quite close to the predicted value.