Abstract
Demand for increased production rates, better quality, and incorporation of
green manufacturing practices has been continually challenging the manufacturers.
This could be feasible by adopting high-speed machining (HSM) using eco-friendly
cutting fluids but with careful process control. On these lines, the current paper
explores process characteristics of the exotic superalloy Inconel 718 being turned at
high speeds with tooling as coated carbide inserts and eco-friendly cutting fluid as
water vapour. The experiments were carried out by varying three process parameters,
viz. cutting speed, feedrate as well as water vapour pressure, following central
composite design based on response surface methodology. A special tool holder with
an in-built fluid supply channel was used to facilitate precise delivery of water vapour
cutting fluid onto the machining zone. The process mechanics has been analyzed with
the aid of the chip deformation coefficient as the same is a crucial indicator revealing
the cutting fluid performance in machining as a result impacting the surface integrity,
tool wear, machinability, etc. Analysis revealed that the response surface quadratic
model for the chip deformation coefficient was statistically significant. The feedrate,
vapour pressure, and the interaction between feedrate and vapour pressure were highly
dominating factors influencing the chip deformation coefficient, with contributions of
around 23.41%, 25.33% and 21.49%, respectively. An increase in vapour pressure was
highly beneficial in lowering the chip deformation coefficient on account of water
vapour’s better penetrability and performance into the machining zone. Overall usage
of cutting fluid as water vapour within feasible HSM parametric ranges can be notably
beneficial.