Optimisation of cutting fluid concentration and operating parameters based on RSM for turning Ti–6Al–4V

The paper details experimental and optimisation results for the effect of cutting fluid concentration and operating parameters on the average surface roughness (Ra) and tool flank wear (V_B) when flooded turning of Ti-6Al-4V using water-miscible vegetable oil-based cutting fluid. Cutting fluid concentration, cutting speed, feed rate, and cutting tool were the control variables. Response surface methodology (RSM) was employed to develop an experimental design and optimise Ra and V_B using linear models. The study revealed that cutting fluid concentration has a little influence on Ra and V_B performance, while Ra was strongly affected by feed rate and cutting tool type. The developed empirical model also suggested that the best parameters setting to minimise Ra and V_B are 5%, 58 m/min and 0.1 mm/rev for cutting fluid concentration, cutting speed, and feed rate, respectively, using H13A tool. At this setting, the predicted surface roughness and tool wear were 0.48 and 30 μm, respectively. In the same vein, tool life and micro-hardness tests were performed at the suggested optimum cutting condition with different cutting speeds. A notable decrease in tool life (82.3%) was obtained when a higher cutting speed was used.