MATERIALI IN TEHNOLOGIJE, vol.48, no.3, pp.373-378, 2014 (SCI-Expanded)
The experimental study presented in this paper aims to select the most suitable cutting and offset parameter combination for a milling process in order to obtain the desired surface roughness value for a machined workpiece of chromium 210 Cr12 steel, in terms of cutting speed, feed rate and depth of cut for the milling process. A series of experiments was performed on chromium material with a cutting width of 50 mm using a round, uncoated, cemented-carbide insert on a engine power 5.5 kW Jhonford VMC550 CNC vertical machining center without any cutting fluid. The experiments were carried out using four different cutting speeds ((70, 90, 110, 130) m/min) at a constant depth of cut (1 mm) and feed rate (0.3 mm/r) and the effects of the cutting speeds on the primary cutting force and the surface roughness were investigated. The cutting force (F-c) and the surface roughness (R-a) decreased with the workpiece material's easy machinability. From the experiments, the highest average primary cutting force was obtained as 658.17 N at a cutting speed of 70 m/min. The lowest average surface roughness was 0.36 mu m, which was obtained at a cutting speed of 70 m/min. The experimental results indicated that the obtained chip form is narrow and short stepped.