Effect of Graphene Addition in Cutting Fluids Applied by MQL in End Milling of AISI 1045 Steel

The cutting fluids applied to the machining processes by the MQL process aim to reduce the machining temperatures and tool wear as well as improve the surface and dimensional finishing of the parts. To increase the efficiency of these fluids, graphene lubricating platelets are added. This work investigated the performance of three different cutting fluids with graphene sheets added and applied via MQL, considering the tool life, wear, and wear mechanisms acting on TiAlN-coated cemented carbide cutting tools in the end milling of AISI 1045 steel. We evaluated two vegetable- (MQL15 and LB1000) and one mineral-based (MQL14) neat oils and the same fluids with the addition of 0.05 and 0.1%wt graphene nanoplatelets. Dry cuts were also performed and investigated for comparison. The experiments were conducted under fixed cutting conditions (vc = 250 m/min, fz = 0.14 mm/tooth, ap = 1 mm, and ae = 20 mm). The end-of-tool-life criterion followed the guidelines of ISO 8688-1 (1989). To analyze the results, ANOVA and Tukey’s test were applied. The addition of graphene sheets in the vegetable-based cutting fluids effectively increased the lubricating properties, partially reducing the wear mechanisms acting on the tools. In addition, there was a predominance of thermal fatigue cracks and mechanical cracks as well as adhesive and abrasive wear mechanisms on the tools used in the cutting with the MQL15 and MQL14 fluids, indicating greater cyclical fluctuations in temperature and surface stresses.