Cutting Forces and Surface Roughness in Face-Milling of SKD61 Hard Steel

This experimental study investigated the effects of milling conditions on cutting forces and finished surface roughness. The face-milling processes were performed using heat-treated SKD61 steel at a hardness of 46 HRC. With three controllable factors/levels (cutting speed, axial depth of cut, and feed rate), the most suitable orthogonal array L 27 was performed with four performance measurements that are amplitudes of cutting forces in three directions (feed, normal, and axial) and surface roughness. With ANOVA analysis, the effect of cutting conditions on the amplitudes of cutting forces and surface roughness were analysed and modelled. The most suitable regression of the cutting force's amplitudes and surface roughness was a quadratic regression with the confidence level is more than 93.74 %, and they were successfully verified via experimental results with very promising results. The relationship between cutting force and surface roughness was also investigated. Furthermore, using the Taguchi and ANOVA methods, the optimization process of surface roughness was performed with very close results (different of surface roughness about 4.58 %). The approach method of the present study can be applied in industrial machining to improve the surface quality in finish face-milling the SKD61 hard steel.