Study on the cooling and lubrication mechanism of magnetic field-assisted Fe3O4@CNTs nanofluid in micro-textured tool cutting

To address the challenge of insufficient lubricity and thermal conductivity of conventional lubricating fluids and single type of nanofluids during cutting, a new nanofluid (Fe3O4@CNTs nanofluid) was prepared in this paper, and the coupling effect of Fe3O4@CNTs nanofluid and micro-texture on the cutting performance of TiC ceramic tools under the action of magnetic field was revealed for the first time. The micro-texture (TTC) was prepared on the rake face of the tool by laser processing technique, and the non-textured tool (TC) was used as a control group. The conventional Fe3O4 nanofluid (F-0.5) and Fe3O4@CNTs composite nanofluid (FC-0.5) and with a volume fraction of 0.5 vol% were prepared by co-precipitation method. For facilitating the penetration of the nanofluid into the tool/chip contact area, an external magnetic field was applied during machining operations. The cutting test of titanium alloy was performed, and the influence of various magnetic field strengths on the friction properties of micro-textured tool/chip interface under the lubrication condition of Fe3O4@CNTs nanofluid was studied. Simulation analysis of the flow characteristics of nanofluid in micro-texture under the action of magnetic field was performed to provide theoretical support for the subsequent results. The results of the cutting tests showed that the cutting forces and tool wear of TTC + FC-0.5 were alleviated in the presence of magnetic field, and the cutting performance was further improved with the increasing of magnetic field from 300 Gs to 1200 Gs. Under the highest magnetic field strength (1200 Gs), TTC + FC-0.5 has 36.9 % lower cutting force and 28.15 % lower surface roughness than TC + F-0.5. Additionally, the penetration and lubrication mechanisms of Fe3O4@CNTs nanofluid on micro-textured tool/chip contact interface under the influence of applied magnetic field was exposed.