Sustainable milling of austenitic and martensitic stainless steels by minimum quantity lubrication method using nanofluids

Stainless steel materials are the materials that are hard to machine due to high strength, low thermal conductivity and work hardening tendency during machining. It is possible that these materials can be machined by using various cutting fluids, but cutting fluids have disadvantages such as being harmful to the environment, health and high cost because of excessive use of these using copiously. In this study, austenitic and martensitic stainless steel materials that are hard to machine, were machinedwithout being harmful to the environment by applying MQL method using nanofluids obtained from mixing commercial vegetable cutting fluid and nano powder. In literature, there area few studies about machining of stainless steel materials by using MQL method.In addition, there is not an application of MQL method using cutting fluid reinforced nano powder(nanofluids). In this study, nano powders such as the nano graphene, MWCNT (Multi-Walled Carbon Nano Tube) and nano MoS2 (Molybdenum Disulphide) were added to the commercial vegetable oil used as cutting fluid to be able to enhance the chilling and lubrication specifications. Austenitic and martensitic stainless steel materials were machined with uncoated and TiN (Titanium Nitride) coated WC (Tungsten Carbide) cutting tools in CNC milling center by applied MQL method using nanofluids. Milling operations were repeated even under dry condition to compare the results obtained from the MQL methods. The effects of the nano powders and the mixing ratios, which were used in different flow rates,on tool wear,surface roughness, cutting temperature, and burr formation were investigated. As a result of experimental studies, it was observed that MQL flow rate and nano powder mixing ratio contributedpositively to milling operation. However, increasing of MWCNT mixing ratio from 0,15%wt.to 0,2%wt. decreased the efficiency of MQL method because of the increasing of viscosity and the tendency of precipitation. When evaluating the nano powders, it was observed that nano graphenewas given the best results. TiN coated WC cutting tool decreasing flank wear, surface roughness, and cutting temperature, provided superior performance than uncoated WC cutting tool. Besides, less and shorter burrs were obtained by using TiN coated WC cutting tool.