Machining Performance of Inconel 718 Under Dry, MQL, and Nanofluid MQL Conditions: Application of Coconut Oil (Base Fluid) and Multi-walled Carbon Nanotubes as Additives

Abstract

The present work intends to investigate the application potential of coconut oil, as cutting fluid, during metal machining of a nickel-based superalloy. In doing so, machining performance of difficult-to-cut aerospace superalloy Inconel 718 is studied under dry, minimum quantity lubrication (MQL), and nanofluid MQL (NFMQL) using uncoated WC–Co tool, operated at varied cutting speeds. MQL environment is created by supplying air-oil mist in which commercially available coconut oil is used as cutting fluid. On the other hand, nanofluid is prepared by dispersing a specific concentration of multi-walled carbon nanotubes within coconut oil. Machining performance as observed in MQL and NFMQL is compared to that of dry machining. The following machining performance indicators are considered herein: cutting force magnitude, tool-tip temperature, and width of flank wear progression. In addition, studies on dominant modes and mechanisms of cutting tool wear, chip morphology (macro/micro), and surface roughness of the machined work part are also carried out. In the purview of machined surface roughness, it is concluded that NFMQL performs better than dry machining and conventional MQL. Flank wear is witnessed more severe during dry machining than MQL/NFMQL. However, beyond 83 m/min cutting speed, conventional MQL outperforms NFMQL (with 0.2 wt% nano-additives concentration) machining, from the viewpoint of flank wear width.