Experimental investigation of the tool radius and micro-cutting speed influence on micro-cutting mechanisms for marble based material

In this paper, a detailed experimental analysis of the effect of tool tip radius and cutting speed on the proposed mechanism of micro-cutting Plavi tok marble was performed. Although Plavi tok marble belongs to extremely brittle materials, experiments have shown that it can be processed in ductile mode (plastic deformation mode), i.e. without the presence of brittle fracturing of the material. Moreover, it has been established that the range of plastic deformation zone is a function of the tool tip radius and the cutting speed. The diamond tools used during the experiments had tip radius values of r = 0.15 and r = 0.2 mm, while cutting speeds were 15 and 25 m s(-1). When using tools with higher tip radius values, with increasing cutting speed, the critical penetration depth (ductile-brittle transition) increased from 8.8 to 9.3 mu m. On the other hand, tools with lower radius value led to a reduction of the plastic deformation zone range. This declining trend of plastic deformation zone continued during increased cutting speed, with critical penetration depths of 8.6 and 8.3 mu m for cutting speeds of 15 and 25 m s(-1), respectively. The intensity of lateral/radial destruction in the brittle fracturing mode was also directly dependent on the processing conditions. The reduction was achieved by using tools with a lower value of the tip radius while processing at lower speeds. In this paper, the identification of the components of the cutting force was carried out, whose intensities indicate the occurrence of the brittle destruction within the material