OBRABOTKAMETALLOV Vol. 28 No. 1 2026 97 TECHNOLOGY References 1. Schenk O., Doost M.V., genannt Wäcken P.B., Meurer M., Bergs T., Broeckmann C. Multiscale characterization of surface integrity of machined Inconel 718. Materials Letters, 2026, vol. 403, p. 139507. DOI: 10.1016/ j.matlet.2025.139507. Sustainability evaluation using an eco-index for Inconel 718 EDM with a hybrid Al2O3-graphene nano-dielectric fl uid Paresh Kulkarni 1, a, Satish Chinchanikar 2, b,* 1 Mechanical Department, D.Y. Patil International University, Akurdi, Pune, Maharashtra, 411044, India 2 Department of Mechanical Engineering, Vishwakarma Institute of Technology, Affi liated to Savitribai Phule Pune University, Pune - 411037, India a https://orcid.org/0000-0002-2761-8754, paresh2410@gmail.com; b https://orcid.org/0000-0002-4175-3098, satish.chinchanikar@vit.edu Obrabotka metallov - Metal Working and Material Science Journal homepage: http://journals.nstu.ru/obrabotka_metallov Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science. 2026 vol. 28 no. 1 pp. 81–100 ISSN: 1994-6309 (print) / 2541-819X (online) DOI: 10.17212/1994-6309-2026-28.1-81-100 ART I CLE I NFO Article history: Received: 01 January 2026 Revised: 14 January 2026 Accepted: 19 January 2026 Available online: 15 March 2026 Keywords: Electrical Discharge Machining (EDM) Inconel 718 Sustainability Nano-dielectric fl uid Eco-index ABSTRACT Introduction. Environmentally sustainable machining is crucial to improve the manufacturing sector’s costeff ectiveness and resource effi ciency while mitigating its negative environmental impact. The “eco-index” is a multi-criteria metric that assesses the sustainability of the electrical discharge machining (EDM) of Inconel 718 by quantifying its total environmental and economic impact using a normalized and weighted approach. The purpose of this work is to describe the eco-index for Inconel 718 EDM, which assesses sustainability through environmental indicators such as energy and material consumption, waste generation, emissions, and toxicity, as well as economic indicators including operating and disposal costs along with productivity metrics. However, there are limited studies on sustainability evaluation using the eco-index for Inconel 718 EDM processed with a hybrid nano-dielectric fl uid. The methods of investigation. This study investigates the machining performance and environmental sustainability of the EDM process of Inconel 718 using a hybrid nanoparticle-mixed dielectric fl uid. A hybrid nano-dielectric fl uid was prepared by dispersing Al2O3 and graphene nanoparticles in an equal proportion (total concentration of 0.1%) in EDM oil using a two-step method involving SDS as a surfactant, magnetic stirring, and ultrasonication to ensure a stable suspension. Experiments were conducted on an EDM machine with a copper electrode by varying the pulse on-time (50–150 μs), peak current (3–10A), and discharge voltage (40–50 V). Key performance responses, including material removal rate (MRR), surface roughness (Ra), tool wear rate (TW), hole cylindricity (ρ), energy consumption (E), and a weighted eco-index (EI), were evaluated to quantify the combined productivity, quality, and sustainability performance. Results and Discussion. The results demonstrate that the hybrid nano-dielectric fl uid improves overall EDM effi ciency compared to conventional EDM oil by promoting stable discharge behaviour, enhanced heat transfer, and effi cient debris fl ushing, which increases MRR, improves surface fi nish, reduces tool wear, enhances the cylindricity of the machined hole, and lowers energy consumption, leading to a higher eco-index across most machining conditions. Surface integrity analysis using SEM revealed a substantial reduction in recast layer thickness, which decreased from 17.05 μm (base oil) to 3.91 μm (hybrid nano-dielectric fl uid), indicating reduced thermal damage and resolidifi cation. EDX further confi rmed nanoparticle involvement through carbon enrichment (graphene deposition) and Al–O signatures (alumina contribution), supporting the proposed mechanisms for improved plasma stability and reduced metallic redeposition. Overall, the hybrid Al2O3–graphene nano-dielectric fl uid provides an eff ective and sustainable approach for the EDM of Inconel 718 by balancing precision, productivity, and environmental effi ciency. For citation: Kulkarni P., Chinchanikar S. Sustainability evaluation using an eco-index for Inconel 718 EDM with a hybrid Al₂O₃-graphene nano-dielectric fl uid. Obrabotka metallov (tekhnologiya, oborudovanie, instrumenty) = Metal Working and Material Science, 2026, vol. 28, no. 1, pp. 81–100. DOI: 10.17212/1994-6309-2026-28.1-81-100. (In Russian). ______ * Corresponding author Satish Chinchanikar, Ph.D. (Engineering), Professor Department of Mechanical Engineering, Vishwakarma Institute of Technology, Affi liated to Savitribai Phule Pune University, Pune – 411037, India Tel.: 91-2026950401, e-mail: satish.chinchanikar@vit.edu
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