Influence of coated and uncoated carbide tools on tool wear and surface quality during dry machining of stainless steel 304

Machining of difficult-to-machine materials has always been a prime area of investigation for researchers. With regard to that tool wear and surface roughness are some of the most important machinability indicators to evaluate the performance of machining processes. This paper reports a part of investigation conducted on dry turning of SS 304 using uncoated and multilayer coated carbide tools. In this work, the influence of machining parameters on tool wear and surface roughness is studied. The mechanisms of both crater wear and flank wear have been analyzed through scanned electron microscopy and energy dispersive spectroscopy. Moreover, surface roughness (mean roughness depth) profiles have been investigated. Carbide tools coated with TiAlN/TiN alternate layers outperformed uncoated tools with a significant reduction in tool flank wear and mean roughness depth (R_z). The percentage reductions in tool flank wear and R_z were investigated at different levels of input machining parameters. On average approximately 25% reduction in tool wear and 15% reduction in R_z was observed using coated tool than uncoated tool. Furthermore, the tool life has been improved by approximately 200% after using coated tools. Comparatively less irregular surface while machining with coated tools has been found than uncoated tools. The research is also complemented with a short chip morphology study. The present work recommends the use of multilayer TiAlN/TiN coating on carbide tools for machining of SS 304 under dry conditions.