Rock cutting by diamond tools: an experimental research

Rock is a random-composite material, and rock cutting diamonds are randomly shaped tools. Based on this, a research program has been planned, starting from single diamond operation on actual rock specimens. Points to be elucidated are the forms of the mathematical linkages between cutting force, normal force, cross section of the kerf produced and rock micro-hardness; the last point, due to obvious scale effects, does not seem to be reasonably predictable from conventional geo-mechanical tests and macroscopic scale cutting tests, nor from conventional rock mechanics theories. Following a synthetic discussion of the problem, the experimental apparatus is described and the results of tests under different conditions are presented. These tests cover the range of the normal and tangential forces applied by a single diamond of a wire saw bead, on different rock types. The results are then analysed, and a mathematical model of the single diamond action, in a form suitable to the application to a simulation of the multi-diamond cutting tool, is presented. In the meantime, the most suitable way to characterise the rock in diamond cuttability problems is discussed and, in particular, the problem of obtaining quantitative micro-strength distribution data from conventional mineralogical-petrographic description is treated.