Surface quality analysis in ball end milling of Inconel 718 cantilevers by response surface methodology

The ball end milling process is commonly used for generating complex three-dimensional sculptured surfaces with definite curvature. In such cases, variation of surface properties along with the machined surface is not well understood. Therefore, this article investigates the effect of machining parameters on the quality of surface in ball end milling of thin-shaped cantilever of Inconel 718. A distinct variation is also observed in the measured values of deflection of workpiece: surface roughness and surface damage in different regions, that is, fixed end, mid portion and free end of machined surface. The experiments were conducted according to the central composite design with four factors, namely, cutting speed, feed, workpiece thickness and workpiece inclination with tool path orientation. It is observed that the process parameters have statistically significant effect on machined surface of Inconel 718. Horizontal tool path condition during milling is most favourable in all aspects of surface quality with high speed and lower feed. The surface roughness values at the fixed end of plate are less as compared with that of mid portion and free end sides. Scanning electron microscope images show various defects such as side flow, smeared layer, microparticle, grooves and feed marks.

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