Study of nanolubricants performance in the turning of AISI D6 tool steel
Hard turning, AISI D6 tool steel, Nanolubricants, MQL
Cutting fluids (based on mineral oil) are widely used in machining processes due to their lubricating and cooling properties. Their use, although quite advantageous to the process, has been questioned due to the presence of toxic substances in their composition that causes damage to the environment and problems of occupational health. This issue has been motivated the emergence of laws to restrict the use of certain products or components considered harmful. In this context, this work aided to evaluate and compare the machining performance of three vegetable-based nanolubricants (epoxidized soybean oil) with the addition of different nanoparticles (CuO, aC: H and CuO + aC: H), supplied in turning process of the tempered and tempered AISI D6 tool steel by MQL technique. For this, facing turning tests were performed with constant cutting parameters (vc = 100 m/min, ap = 0.3 mm and f = 0.1 mm/rot.) with PCBN cutting tools. For comparison, tests were performed with a mineral oil emulsion in flood technique and with pure vegetable oil (without the addition of nanoparticles) applied by MQL. The average roughness (Ra) of the machined surface, the wear and wear mechanisms of the cutting tools and the shape and appearance of the chips were investigated. The nanofluid of aC: H and the hybrid (CuO + aC: H), provided a longer useful life when compared to a dry condition, as well as chips with a higher thickness ratio, which may indicate, in an previous way, lower efforts for chip formation. For roughness, the wet condition was the one that presented the lower values, the MQL conditions presented lower values than those obtained with dry machining but without significant difference between them.