Study of Cerchar abrasive parameters of monomineralic rocks and its application for evaluating cutting efficiency

The Cerchar test is the most commonly used method for evaluating rock abrasivity and estimating tool wear. The conventional test results are reported based on the measured changes of the wear parts, and little attention is paid to what happens on the rock surface and scratching force. Since the cutting process is the interactive behavior between cutting tools and rock materials, the changes in both parts are important to represent rock-tool interaction and evaluate cutting efficiency. In the present study, the Cerchar tests have been carried out on eleven types of monomineralic rocks by using an improved West apparatus. The related abrasive parameters have been comprehensively and systematically analyzed, including stylus tip wear, rock material loss, applied horizontal force, and scratching energy. The variation characteristics of those abrasive parameters have been studied. The specific abrasivity ratio (SAR) and scratching specific energy (SSE), which represent the tool wear and energy consumption per unit of rock removal respectively, have been developed to evaluate the cutting efficiency of different rocks. The results show that the SAR and SSE values of the tested rocks have comparable data ranges and variation trends due to the same mathematical treatment of the indices. Under the given rock removal volume, the SAR and SSE could be used to compare and classify the relative cutting efficiency of different rocks. The lower the SAR and SSE values, the less stylus wear and lower energy consumption in the cutting process, indicating higher cutting efficiency. According to their values, the cutting efficiency of the tested rocks is divided into four categories: high cutting efficiency, medium cutting efficiency, low cutting efficiency, and very low cutting efficiency. The SAR-based and SSE-based classifications are consistent for most of the tested rocks, and the SAR-based classification is lower to higher abrasive rocks (pyroxene, hematite, and quartz) due to it considering the influence of stylus tip wear. Hence the SAR-based classification is more suitable for hard and highly abrasive rocks.