MQL milling of TC4 alloy by dispersing graphene into vegetable oil-based cutting fluid

Titanium alloy TC4 is widely used in aerospace, petrochemical, shipbuilding, automobile, and medicine due to its excellent comprehensive performances. However, TC4 is a difficult-to-machine material because of its low thermal conductivity, large friction coefficient, high chemical activity, and low elasticity modulus. In this paper, Minimum Quantity Lubrication (MQL) with vegetable oil-based cutting fluid was adopted in TC4 milling. Meanwhile, graphene nanoparticles were dispersed into the vegetable oil-based cutting fluid to improve the cooling and lubrication performances. In order to evaluate the performances, a series of milling experiments were conducted under the four cooling/lubrication conditions (dry, gas, pure MQL, and graphene MQL). The milling characteristics of TC4 in terms of milling force, milling temperature, tool wear, and surface integrity were compared. Results showed that the graphene additive was effective for improving the milling characteristics. Overall, the results could be explained that the graphene additive could enhance the cooling and lubrication performances of the oil film formed in the milling zone. The findings of this paper are expected to be meaningful to provide some experimental basis for the application of the graphene additive in MQL milling.