Effect of Machining Parameters on Surface Integrity in End Milling of Inconel 625

Abstract

This study exclusively deals with surface integrity aspects, such as residual stresses, surface roughness, and micro-hardness, in the end milling of Inconel 625 using TiAlSiN-coated carbide-cutting tools distinctively developed for dry machining of the nickel-based superalloy. The aim of this research was to build up a set of guiding principles, which would help out the selection of the proper cutting conditions and tool geometry to enhance surface integrity of nickel-based superalloy Inconel 625. As part of the study, the effect of cutting speed, feed per tooth, radial depth of cut and radial rake angle on surface roughness, residual stresses and micro-hardness was studied. It was observed from results of analysis of variance that the surface roughness is significantly influenced by feed per tooth, followed by cutting speed, while radial depths of cut and radial rake angle have a small influence. The experimental results revealed that the minimum surface roughness (0.084 µm), residual stress (123.2 Mpa) and maximum micro-hardness (344) were observed at higher cutting speed (90 m/min), positive radial rake angle (13°), lower feed per tooth (0.05 mm/tooth), and lower radial depth of cut (0.2 mm). Based on the experimental analysis, it was observed that the higher cutting speed, the lowest feed per tooth, and lower radial depth of cut coupled with the use of positive radial rake angle can ensure induction of superior surface integrity in the machined surfaces.