Investigation of scratching specific energy in the Cerchar abrasivity test and its application for evaluating rock-tool interaction and efficiency of rock cutting

Wear occurs on mechanical tools during rock cutting and drilling, or any other kind of mechanical based excavation of rocks. The determination of rock abrasivity plays therefore a key role for estimating the tool's lifetime and for evaluating the economic efficiency. Due to simple design and convenient handling, the Cerchar abrasivity test is commonly used to assess the rock abrasivity and to predict the tool wear. However, the abrasivity index reflects only the abrasion of the stylus, and does not consider what happens on the tested rocks, as well as on how the stylus interacts with the rock during the scratching process. In this paper, an instrumented West apparatus is used to determine the applied horizontal force in the Cerchar test. The area under the forcedisplacement curve represents the consumed scratching energy. The material removed from the rock surface is measured using a digital microscope. Then, a new parameter called Cerchar specific energy, which is defined as the ratio of scratching energy to material removal volume, is proposed to assess the rock abrasivity, to describe the rock-stylus interaction, as well as to evaluate the efficiency of rock scratching, which can be used as indicator for rock cutting or drilling efficiency.