Comparison of VT-20 alloy drilling performance evaluation under dry, MQL, EMQL, and hybrid nanoparticle assisted EMQL ecological conditions

Abstract

The potential of VT-20, a titanium (Ti) alloy in the aircraft industry, is increased as it has stronger thermal capabilities than other pseudo-α-Ti alloys. However, the alloy’s low heat conductivity and chemical reactivity make machining difficult and necessitate efficient cooling/lubrication. Cutting oils based on emulsion have been used to move heat from the cutting region; however, they are not sustainable due to their negative impacts on workers’ health and the environment. Therefore, this novel study investigates alternative lubricating approaches, such as drilling VT-20 alloy under dry, MQL, EMQL, and HNPEMQL conditions using SEM and line-scan EDS analysis. An indigenously developed electrostatic minimum quantity lubrication (EMQL) and hybrid nanoparticles (NPs) immersed in EMQL (HNPEMQL) techniques were utilized to improve drilling performance while reducing cutting oil consumption. Hybrid nanofluids for HNPEMQL application were developed using aluminium oxide (Al2O3) and plate-structured graphene nanoparticles using a two-step process. The surface quality of the drilled hole, tool wear, thrust force, power consumption, hole quality indicators, and microhardness are evaluated. The efficacy of HNPEMQL showed improved drilling efficiency compared to dry, MQL, and EMQL machining. HNPEMQL, EMQL, and MQL conditions reduced tool wear by 102 %, 53 %, and 19 %, respectively, to dry drilling. The HNPEMQL condition lowered the thrust force by 75.3 %, 28.69 %, and 18.02 %, respectively, compared to the dry, MQL, and EMQL. HNPEMQL demonstrated a 105 %, 41 %, and 22 % reduced variation in circularity values than dry, MQL, and EMQL for the same number of drilled holes. The findings show that HNPEMQL can be considered a promising cooling and lubricating strategy with improved drilling performance and quality.