A CONTRIBUTION TO GRINDING OF TITANIUM Ti-6Al-4VALLOY WITH VARIOUS COOLANT DELIVERY TECHNIQUES
Antonio Vitor de Mello1; Rosemar Batista da Silva1; Cleudes Guimaraes1; Raphael Lima de Paiva1; Armando Marques2; Rogerio Valentim Gelamo3; Fabio Martinho Cezar de Freitas4
1 Universidade Federal de Uberlandia; 2 Federal University of Uberlandia; 3 Federal University of Triangulo Mineiro, UFTM; 4 Saint-Gobain Abrasivos América do Sul
doi:10.20906/CPS/COB-2015-2581
Resumo
Most application of Ti-6Al-4V alloy is in aerospace and biomedical industries, but its application in automotive and cutting implements, like scissors and knives, for example, has also become more commonly employed. Although Ti-6Al-4V alloy is not as hard as medium carbon steel, it possesses some outstanding properties such as: it is virtually unbreakable, high strength-to-weight ratio and excellent resistance to corrosion in many environments. However, Ti-6Al-4V alloy is referred as difficult-to-cut material due to its unique combination of low thermal conductivity, high chemical reactivity with most cutting tools and rapid work hardening during machining that affect quality of the machined component. As a result of its poor thermal conductivity, heat is more concentrated in the cutting zone. This will become more critical in grinding operation, since ordinary abrasive wheels have also poor conductivity property. Then, an effective coolant delivery combined with a cutting fluid having outstanding coolant properties, as well was, geometry and positioning of jet nozzle will help to minimize heat in the cutting zone and consequently avoiding dimensional and geometrical distortions of the machined surface. Although many studies about machining of titanium at different cutting fluid delivery techniques have been related to turning and milling operations, information about grinding operation is still few. Into this context, this work presents the results of grinding Ti-6Al-4V alloy with different coolant delivery techniques as a contribution to machining field. The minimal quantity of lubrication technique (MQL) and conventional technique (flooding) were employed as well as jet nozzle positioning was varied. Two radial depth of cut values were tested. Ra surface roughness parameter was the output parameter analyzed. Images of the machined surfaces were also obtained via SEM. Results show that surface roughness is dependent on the positioning of nozzle and it increased with depth of cut. Ra values were below 0.90 µm fo
Palavras-chave: grinding; Ti-6Al-4V alloy; MQL technique; nozzle positioning; surface roughness; micro-cracks