Reducing surface roughness by varying aerosol temperature with minimum quantity lubrication in machining AISI P20 and D2 steels

Heat generation in metal cutting leads to numerous problems. Despite the development of many different cooling and lubrication methods in industry, opportunities are still open to develop novel methods. Minimum quantity lubrication (MQL) is a recent such development that has shown promising results. However, the effect of aerosol temperature on machining performance has not yet been studied in depth. Thus, the aim of this study is to explore the ability to improve surface roughness in machining by lowering the MQL aerosol temperature. To study the effect of the aerosol temperature in MQL, an experimental investigation is carried out using a simple turning operation on AISI P20 and D2 steels, with cutting tools and cutting fluids (CF) typically used in industry. The arithmetic average surface roughness of the workpiece is measured for each of the treatments. Measurements are taken with dry cutting condition, conventional flood cooling method, and several MQL temperatures. Significantly lower surface roughness in the workpieces is observed for all considered MQL temperatures in comparison to dry cutting and flood cooling conditions. Furthermore, a reducing trend with a quadratic behaviour in surface roughness is observed with decreasing temperatures. The lowest surface roughness is observed at MQL 5 °C for both material. Interestingly, the effect of aerosol temperature is observed to be high with D2 steel and lower temperatures achieved up to 50% reduction in surface roughness. The study concludes that surface roughness can be reduced using low-temperature MQL. The effect of the aerosol temperature on other tool-work material combinations and tribology studies are suggested as further work.