Tool surface modification methodology to improve the machinability of Ti6Al4V through combination of micro-EDM texturing and AlSi-10Mg soft coating techniques in dry turning

Abstract

Machinability of Ti-6Al-4V, despite its numerous applications, is challenging owing to its poor thermal conductivity, severe chemical affinity and strain hardening characteristics. Although various coating techniques and expensive lubrication strategies have been tried, a significant improvement in tool life characteristics are yet to be achieved. Hence this work aims at suggesting a novel cost-effective and ecofriendly tool treatment technique by exploring the impact of a dual combination of an AlSi-10Mg coating developed by an emerging pre-conditioning technique with the incorporation of micro-textures on tool face to observe significant improvements in tool life and machinability characteristics of the alloy. It was analyzed from the results that while the micro-textures played a vital role in reducing the severe contact stress and machining temperature due to its improved heat transfer by convection, AlSi-10Mg film effectively shielded the cutting edges of the tool by providing a dampening effect along the edges, thereby ensuring improved tool life and enhanced machinability characteristics at the same time. The proposed tool combination was observed to be successful in significantly reducing the flank wear by 35%, 43% and 30% where 75, 253, and 371 µm were observed at 80, 100, and 120 m/min as compared to 117, 449, and 531 µm in the case of uncoated non-textured tool at the same operating conditions. Surface roughness of Ti-6Al-4V also reduced by 25%, 34%, and 37% where 1394, 1168, and 872 nm as compared to plain tool where 1840, 1770, and 1370 nm were recorded. Moreover, average chip curl diameter was observed to be 2.62, 3.36, and 6.49 mm as compared to chips generated by uncoated tools which recorded values of 4.33, 11.9, and 18.87 mm at 80, 100, and 120 m/min respectively.