Performance improvement of eco-friendly MQL technique by using hybrid nanofluid and ultrasonic-assisted grinding

MQL technique has many technological and economic advantages in grinding operation. It can improve grinding performance in terms of surface integrity, grinding forces and G-ratio. On the other hand, MQL is eco-friendly technique because of its small consumption of cutting fluid. Despite these advantages, MQL technique has a serious thermal problem in grinding operations due to a small amount of cooling. Nanofluids can increase heat transfer from workpiece/wheel interface due to its high thermal conductivity. On the other hand, ultrasonic machining can decrease heat generation due to its reciprocating mechanism and reduction of time and length of contact between grain and workpiece. So, it is anticipated that simultaneous utilization of these techniques can reduce thermal damages. In this research MWCNT, Al2O3 and hybrid MWCNT/Al2O3 nanofluid oil mists have been utilized in ultrasonic assisted grinding. MWCNT has high thermal conductivity and Al2O3 has good lubrication effect. Output parameters were maximum temperature, grinding forces and friction coefficient. The results revealed that combination of MQL and UAG decrease of maximum grinding temperature up to 56.3% in comparison to dry grinding (from 254 to 111 °C). Moreover, tangential and normal grinding forces and friction coefficient have been reduced up to 61.5, 47.1, and 27.3%, respectively. Moreover, shiny surface without any thermal damages and burning obtained in comparison to dark and burned surface in dry grinding.