Influence of Technology Parameters on the Total Cutting Force in the Hard Turning Process with NF MQL and NF MQCL Method Using Nanofluids

Hard turning technology has received much attention and is becoming an alternative to the grinding process due to its high productivity, suitability for complex profiles, reduced use of cutting oil, and good surface quality. However, very severe cutting zone conditions such as very high friction, cutting forces and temperature in the cutting zone require special cutting tool materials and limited cutting modes. MQL and MQCL methods with nano-cutting oils are used to support hard-turning processes that improve cutting efficiency while ensuring environmentally friendly properties. Currently, the selection of suitable lubrication methods, base oil, and nanoparticle type is an issue that needs to be researched. Moreover, the trend of researching suitable lubricating technology so that conventional cutting tools (carbide inserts) can be used in hard machining is also an interesting research trend. This paper focuses on analyzing and evaluating the machining efficiency when turning 90CrSi (60 - 62 HRC) steel using MQL and MQCL by adding Al2O3 and MoS2 nanoparticles to the base liquid (soybean oil and emulsion). Analysis of variance (ANOVA) was used to evaluate the influence of the MQL and MQCL parameters on the total cutting force. At the same time, the trend and influence of the parameters MQL and MQCL on the total cutting force are also analyzed. The obtained results showed that the uses of MQL with nanofluid made from MoS2 and emulsion or MQCL with nanofluid made from Al2O3 and soybean can significantly reduce the total cutting force. The obtained results showed that the machinability of carbide inserts was improved and the highest machinable hardness was increased from 35 HRC to 60 ÷ 62 HRC (rising by approximately 75%) by using the nanofluid MQL and MQCL methods. Furthermore, MQCL gives better performance than MQL, and the MoS2 nanofluid exhibits a better result in terms of the total cutting force values than the Al2O3 nanofluid. From these results, technical guidance will be provided for further studies using Al2O3, MoS2 or hybrid Al2O3/MoS2 nanofluids for MQL and MQCL methods, as well as their application in machining practice.