A comprehensive investigation on eco-benign grindability improvement of Inconel 625 using nano-MQL

This work uses an alumina wheel to investigate the eco-benign grinding for better surface integrity of Inconel 625 (IN 625). To achieve this, applying nanofluids (NFs) with the minimum quantity lubrication (MQL) principle has been adopted, aiming at eco-benign grinding practices. In this work, MoS₂ NFs, MWCNTs NFs and hybrid NFs (prepared by mixing MoS₂ and MWCNTs in a 1:1 ratio) prepared using deionized water as the base fluid have been used. An in-house developed MQL setup is used to aim the NFs inside the grinding zone. The first attempt has been made to grind IN 625 in these environments. The characterisation of NFs in terms of nanofluid stability, dynamic viscosity, thermal conductivity and surface wettability have been performed before their utilization in grinding operations. A comparison has been made between the results obtained from NFs grinding and those from dry and soluble oil-based MQL grinding. It has been found that hybrid NFs provide excellent lubrication and cooling effects, reducing grinding forces and improving surface quality. Moreover, scanning electron microscopy, energy-dispersive spectroscopy and X-ray photon spectroscopy are applied to investigate the ground surfaces under different grinding conditions. Also, residual stress (with the help of X-ray diffraction and electron backscattered diffraction) and microhardness have been determined to gain further insights into the grinding behaviour. The wheel and chip morphology analyses have been performed to support the findings. The findings from this investigation lead to the conclusion that applying nano-MQL improves grinding effectiveness and promotes cleaner grinding outcomes. Hybrid NFs prove especially effective, as the physical synergistic effect enhances and safeguards the surface integrity of the produced ground components.