Comparison between Nitrogen-Oil-Mist and Air-Oil-Mist Condition when Turning of Hardened Tool Stainless Steel

Minimum quantity lubrication (MQL) or as it’s called semi dry cutting is a technique which spray a small value of lubricant flow rate to the cutting zone area. MQL has been used in many machining process with different cutting tools and workpiece materials due to its green environments and economically advantageous. MQL has become an attractive option to dry and flood cutting in terms of reduce the temperature in the cutting zone and reduce the cost of the product. However, in MQL seems to be machining limited by cutting temperature, because at high speed the effect of oil mist becomes evaporated. Therefore another alternative cooling approach was used with oil mist in this research. This research presents study the performance of nitrogen gas as a coolant and oil mist as lubricant in turning of hardened stainless tool steel (STAVAX ESR) with hardness 48 HRC. Using a gas as coolant with oil mist is a new solution for enhancing machinability. Turning experiments are carried out on CNC turning machine. The cutting insert grade is KC5010 (PVD-TiAlN wiper coated carbide). The experimental results were: 1) nitrogen gas with oil mist prolongs tool life compare with air with oil mist. 2) better product surface finish by using nitrogen gas with oil mist.