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.
Highlights
With the increasing population and higher demand for industrial products, energy consumption is increasing
The novelty of the present work lies in (1) the development of new empirical models for production time, energy consumption, CO2 emission, and production cost; (2) determining optimal resource consumption for economical and energy-efficient machining processes; Metals 2021, 11, 88 (3) synergetic reduction in electrical and embodied energies; (4) holistic sustainability assessment and comparison of two different approaches based on 4E methodology
The electrical energy consumed during machining stages and embodied energy used by consumed resources are responsible for CO2 emission
Summary
With the increasing population and higher demand for industrial products, energy consumption is increasing. Carbon price/carbon tax is known as an environmental cost, and it is a tax on carbon-based energy which can help to decrease the demand for energy-intensive processes or force the producer to switch to other sustainable approaches [4]. Both academia and the metal processing industry are trying to cope with challenges occurring during the machining of difficult-to-cut materials. The novelty of the present work lies in (1) the development of new empirical models for production time, energy consumption, CO2 emission, and production cost; (2) determining optimal resource consumption for economical and energy-efficient machining processes; Metals 2021, 11, 88. (3) synergetic reduction in electrical and embodied energies; (4) holistic sustainability assessment and comparison of two different approaches based on 4E methodology
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