Machining performance and sustainability analysis of Al₂O₃-CuO hybrid nanofluid MQL application for milling of Ti-6Al-4V

Abstract

Machining of Ti-6Al-4V presents challenges due to its low thermal conductivity, and conventional cutting fluids (CCF) are inadequate in providing a productive and sustainable solution. This study aims to achieve more sustainable and productive machining of Ti-6Al-4V by utilizing Al₂O₃ and CuO-added Nanofluid Minimum Quantity Lubrication (NMQL) individually and in hybrid form with different concentrations. A comparison is made with pure-MQL, CCF and dry conditions. The study consists of three stages. In the first stage, the physical properties of the coolants, like contact angle and surface tension, are investigated. The second stage involves slot milling operations, and various outputs including cutting forces, surface roughness, surface topography, surface finish, and subsurface microhardness are analyzed. In the last stage, a sustainability analysis is conducted based on the Pugh Matrix Approach. The results indicate that Al₂O₃-NMQL exhibits lower contact angles and surface tensions compared to other conditions. Furthermore, HNMQL applications result in lower cutting forces (up to 46.5%), surface roughness (up to 61.2%), and microhardness (up to 6.6%), while yielding better surface finish and topography compared to CCF. The sustainability analysis demonstrates that HNMQL application is the most suitable option for achieving sustainable machining of Ti-6Al-4V.

Keywords:

• Ti-6Al-4V
• nanofluid minimum quantity lubrication
• cutting force
• surface quality
• microhardness
• sustainability assessment

Acknowledgment

The authors express their gratitude to Belgin Oil Company for providing the MQL oil, Atılım University Department of Chemical Engineering for their assistance during nanofluid preparation, Atılım University Metallurgy and Materials Engineering Department for their support in sample preparation and the use of the microhardness device, and Dr. C. Merih Şengönül for facilitating the use of the optical tensiometer.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research was supported by The Scientific and Technological Research Council of Turkey (TÜBİTAK), under grant number 222M381.