In recent years, the use of cutting fluids has become crucial in hard metal
machining. Traditional non-biodegradable cutting fluids have long dominated
various industries for machining. This research presents an innovative approach
by suggesting a sustainable alternative: a cutting fluid made from a blend of
glycerol (GOL) and distilled water (DW). We conducted a thorough investigation,
creating 11 different GOL and DW mixtures in 10% weight increments. These
mixtures were rigorously tested through 176 experiments with varying loads and
rotational speeds. Using Design-Expert software (DES), we identified the optimal
composition to be 70% GOL and 30% DW, with the lowest coefficient of friction
(CFN). Building on this promising fluid, we explored further improvements by
adding three nanoscale additives: Nano-graphite (GHT), zinc oxide (ZnO), and
reduced graphene oxide (RGRO) at different weight percentages (0.06%, 0.08%,
0.1%, and 0.3%). Comparative tests using a four-ball wear tester revealed that
the fluid with 0.08% nano-GHT performed the best, boasting a CFN of 0.039,
surpassing both the unmodified fluid and conventional commercial cutting fluids
(CMCFs). To validate the practicality of this novel cutting fluid, we conducted
machining experiments on EN31 material. Our comprehensive analysis, including
surface roughness, chip formation, and scanning electron microscopy (SEM)
examination, compared the outcomes with those obtained using a CMCF. Overall,
our study highlights the advantages of the optimized cutting fluid composed of
70% GOL + 30% DW and 0.08% nano-GHT. It delivers enhanced machining performance
while promoting environmental sustainability in machining operations.
