Energy, Environmental, Economic, and Technological Analysis of Al-GnP Nanofluid- and Cryogenic LN2-Assisted Sustainable Machining of Ti-6Al-4V Alloy

Abstract

The quest for advanced cooling/lubrication approaches for energy-efficient, eco-benign, and cost-effective sustainable machining processes is garnering attention in academia and industry. Electrical and embodied energy consumption plays an important role in reducing CO2 emissions. In the present study, new empirical models are proposed to assess sustainable indicators. The embodied energy, environmental burden, and cost of coolant/lubricant have been added in the proposed models. Initially, optimal levels of minimum quantity lubrication (MQL) oil flow rate, liquid LN2 flow rate, air pressure, and nanoparticle concentration were found. Based on optimal technological parameters, experiments were performed under the same cutting conditions (machining parameters) for MQL and cryogenic LN2-assisted external turning of Ti6-Al-4V titanium alloy. The electric power and energy consumption, production time/cost, and CO2 emissions were assessed for a unit cutting-tool life. Later, specific responses were measured and compared between both cooling and lubrication approaches. Results showed that hybrid Al-GnP nanofluid consumed 80.6% less specific cumulative energy and emitted 88.7% less total CO2 emissions. However, cryogenic LN2 extended tool life by nearly 70% and incurred 4.12% less specific costs with 11.1% better surface quality. In summary, after Energy–Economy–Ecology–Engineering technology (4E)-based analysis, cryogenic LN2 is sustainable economically but not environmentally and there is a need to improve the sustainable production of LN2 at an industrial scale to achieve environmental sustainability. The present study provides useful information to establish clean machining processes.

Nano-enhanced biolubricant in sustainable manufacturing: From processability to mechanisms

“…They suggesting that the mixing of CNT with Al 2 O 3 improves the spreadability, thanks to its smallest contact angle. In another researches, although lubrication performance was improved by composite of MoS 2 / Al 2 O 3 [122], CNT/Al 2 O 3 [123] and graphene/Al 2 O 3 [124][125][126], they found that it also affects the thermal conductivity negatively. This phenomenon maybe caused by increased viscosity of composite NEBL compared with mono NEBL, which weakens cooling performance.…”

Experimental analysis of cutting force during machining difficult to cut materials under dry, mineral oil, and TiO2 nano-lubricant

“…This proves that high cutting speed with low feed interactions leads to minimum cutting force during machining of Ti-6AL-4V-ELI alloy. Because the application of the nanoparticles in the mineral oil increases the mechanical property of the base oil, which significantly improves the machining condition during operation to reduce vibration and friction during the face-milling machining, this result is in line with [25,[31][32][33]. The vibration occurs due to the unwanted movement of the chips being removed from the workpiece in the machining process and can affect the workpiece during the machining operation.…”

Cryogenic minimum quantity lubrication machining: from mechanism to application

“…Thus far, the main cryogenic media for difficult-to-cut materials include liquid nitrogen (LN 2 ) [31], liquid carbon dioxide (LCO 2 ) [32], supercritical carbon dioxide (scCO 2 ) [33], and cryogenic air (CA) [34]. A low temperature can reduce the thermal softening degree of the workpiece and improve the cutting performance, which not only enhances the material removal rate of the workpiece but also effectively extends tool life [35]. The cost of cryogenic machining is lower than that of traditional machining methods considering high tool life and productivity [36][37][38].…”