Effect of cutting speed and feed on surface roughness in dry turning of Inconel X-750

Abstract

Dry turning is one of the sustainable way to achieve sustainability in machining but due to low heat precipitation rate of Inconel X 750, the excess temperature is generated during dry cutting which further causes built-up-edge formation and consequently creates poor surface finish. As a general practice, sharp edge of cutting tool reduces the vibration and enhances the surface roughness. Accordingly, the use of small nose radius is a better solution to smoothly cut the HRSA materials. Therefore, an attempt has made to study the effect of cutting speed and feed rate on surface roughness during turning of Inconel X-750 under dry environment by using PVD TiAlN coated negative inserts with small tool nose radius of 0.4 mm. The cutting speed and feed has been applied in three different ranges viz. 60,80 & 100 m/min and 0.05, 0.1 and 0.15 mm/rev respectively. Whereas, the depth of cut of 0.5 mm has kept constant for all experiments. In most of the cases it is noticed that with Ra value goes on increasing and found within acceptable range with increase in cutting speed and feed. However, at feed rate of 0.1 mm/rev with corresponding speed of 100 m/min, the continuous chips are produced which caused the rubbing action. Hence, excessive localized heat is generated at chip-tool interface and built up edge is formed. Consequently, the poor surface finish is produced due to the hard turning. The highest cutting speed and feed of 100 m/min and 0.15 mm/rev respectively found to be optimum cutting condition which imparted acceptable surface roughness value of 1.50 µm as per ANSI/ASME B46.1–2009 standards. The cutting speed and feed rate are found to be important parameters while studying surface roughness. However, In comparison to cutting speed, the feed rate havegreater impact on surface integrity.