Investigation the effects of minimum quantity lubrication on surface roughness and tool wear in milling of Hastelloy C276 alloy

In this study, the effects of cutting parameters, Minimum Quantity Lubrication (MQL) and Nano-MQL on machining performance in milling of Hastelloy C276 superalloy were investigated. The experiments were carried out in CNC machining center using CVD coated cemented carbide tools. In the first stage of the optimization of MQL parameters for surface roughness was performed by using Taguchi's L9 experimental design. At this stage, flow rate (20, 60 and 100 ml/h), nozzle angle (30, 45 and 60°) and pressure (4, 6 and 8 bar) were considered as control factors and cutting speed (75 m/min), feed rate (0.15 mm/rev) and cutting depth (0.5 mm) were kept constant. According to the test results, the best surface roughness value was obtained in 100 ml/h flow rate, 45° nozzle angle and 8 bar pressure. According to the analysis of variance, the most effective factor on surface roughness was the flow rate with a contribution rate of 74.6%. This was followed by pressure and nozzle angle, with contrubition rates of 9.1% and 3.3%, respectively. In the second stage, the effects of Nano-MQL and cutting parameters on machining performance were investigated by considering the optimum MQL parameters obtained in the first stage. For this purpose, full factorial experiment design was performed by using Taguchi's L27 vertical array. Surface roughness and tool life were considered as performance characteristics in the experimental design. Cutting speed (60, 75 and 90 m/min), feed rate (0.1, 0.15 and 0.20 mm/rev) and nanoparticle concentration ratio (0.5, 1 and 1.5% by volume) were determined as control factors. According to the test results, the best surface roughness value was obtained at a cutting speed of 90 m/min at 0.1 mm/rev feed rate with a concentration rate of 1% by volume. The highest tool life was obtained at a cutting speed of 60 m/min at a feed rate of 0.1 mm/rev at a feed rate with a concentration rate of 1% by volume. According to the analysis of variance, the most effective parameter was the feed rate with 56.2% contribution rate on surface roughness and cutting speed with 49.1% contribution rate in tool life.