Evaluation of Cutting Forces and Surface Integrity in Flank Milling of Heat-Resistant-Super-Alloys with Coated Cemented Carbide Tools

In aerospace industry, heat-resistant-super-alloys (HRSA) are widely used for its high strength, high hardness and low thermal diffusivity at high temperature. Flank milling is performed by employing the side of a cutter to touch the desired workpiece surface. Compared to traditional point milling, flank milling has attracted interest because of its high material removal rate and no scallops on the workpiece for single passage flank milling. Experimental investigation of the cutting performance in flank milling of HRSA is a preliminary step to the practical usage of HRSA, although this issue is absent to date. This paper firstly reviews the state of the art on the cutting forces and surface integrity in HRSA milling process. Then the experimental studies of cutting forces variation and surface integrity in flank milling of HRSA with PVD coated cemented carbide tools are presented. The cutting tests are performed at various cutting speeds (40–120 m/min), cutting depths (9–15 mm) and feed rates (0.03–0.09 mm/rev) in flank milling under lubricant condition. Additional measurements (surface roughness, residual stresses, microstructure and micro-hardness) are performed with the sample of the machined surface in addition to the cutting forces. The feed rate is the most influential parameter with surface roughness in flank milling operation. The tensile residual stresses are observed on the machined surface and a work hardening layer arises beneath the machined surface. The results show that the lower cutting forces and smaller micro-hardness generated with the higher cutting speed. The detailed analysis of the relationship between cutting parameters and surface micro-hardness is given in this paper.