Effects of the granite forming minerals on the surface roughness in the milling processes
Six lines were formed on the surface of each granite specimen by milling. Milling was done by the same machine (Prussiani Golden Plus), with the same parameters (1 mm cutting depth, 40 mm cutting width and 0,1 mm/min feedrate), with the same tools (60 mm diameter, milling tool with 8 segments). While numerous parameters are constant, the rotational speed of spindle was changed and the cutting speed was calculated (37,7 m/min, 75,4 m/min, 113,1 m/min, 150,8 m/min, 188,5 m/min, 226,2 m/min) based on this rotational speed. The area-based average surface roughness of the minerals was measured in the granite. These component minerals were quartz, mica and feldspar. Quartz, albite and biotite were constant components in each sample. However, in the first two specimens, orthoclase and mica were observed along with albite. For exact surface roughness, measurements were made at the beginning, middle and end of the line. The surfaces of the samples were cleaned with high pressure air. Then the specimens were put under an Alicona InfiniteFocus IFM G4 confocal microscope. InfiniteFocus is a fast and flexible optical 3D surface measurement system. During the study, the focus was set to include the roughness peaks and roughness valleys. If the focus is poor, the surface roughness cannot be evaluated. Precise measurement is also supported by the precise movement of the InfiniteFocus object-slide. The surface roughness of the selected minerals was calculated by the evaluation software of the microscope. During the experiment, area-based roughness was measured instead of line-based roughness to obtain more accurate results. So, it can be stated that the order of the effect of minerals on surface roughness is the same at all cutting speeds and every particle size. The results may be greatly influenced by the microhardness of the minerals, their different orientation, and the percentage composition of the sample.