Influência do fluido lubrirrefrigerante sobre o desgaste emtorneamento de tubos de ferro fundido

Abstract

This study evaluated the influence of different lubrication/cooling conditions (dry, MQL - Minimum Quantity Lubrication, and flood coolant) on insert wear during the turning of centrifuged gray cast iron tubes. The presence of surface carbides, resulting from the centrifugation process, adds complexity to the machining of this material. The objectives included analyzing the effects of the cutting fluids on wear mechanisms and their impact on tool life. Furthermore, the impact of fluid reduction on equipment cleanliness and part handling was analyzed, in addition to the physical characterization of wear and the use of statistical analysis. The methodology employed a controlled experimental design with constant cutting parameters on Alloy 8 ABNT NBR 16080 material and Mitsubishi SNMA 120412 MC5005 inserts, with an end-of-life criterion defined by a flank wear (VBmax) de 0.3 mm. The tests were performed similarly on the same CNC lathe. The results identified the wear types; in all three cases, they were characterized by abrasion, followed by adhesion and oxidation, according to results obtained through Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS) analysis. Regarding tool life and wear, the tests with flood coolant achieved a longer insert life in machined meters compared to dry and MQL tests. It was observed, through the collected data, that the flood coolant and dry tests showed behavior characterized by three wear stages: initial rapid wear (break-in), followed by steady-state wear, and finally accelerated wear, which is characteristic of the tool's end of life. The MQL test presented wear fluctuation and proved unstable in estimating the tool life trend, despite showing residual values within the expected range. [resumo fornecido pelo autor]