Evaluation of fine material and chip formation in rock cutting with a conical tool

The production of fines and chips during rock cutting plays an essential role in the efficiency of rock cutting, which in turn impacts productivity and performance of mechanical excavators. In this study, small scale linear rock cutting experiments were conducted using a conical tool on thirteen sedimentary and metamorphic rock samples to evaluate the transition between ductile to brittle cutting mode by examining the volume of fines versus chips produced in the process of cutting. Cuts with depths of 0.5, 0.8, 1, 2, 3, 4, 5, and 6 mm were made to investigate the production of fines and chips in unrelieved cutting mode. The forces acting on the conical tool, cutting rate, and volume of fines were measured. Initially, the critical cutting depth was determined by analyzing the cutting force signals, aiming to identify both ductile and brittle cutting failure zones. Subsequently, the percentage of fines were classified into three classes using the hierarchical clustering algorithm. Finally, the support vector machine algorithm was employed to create a two-dimensional space utilizing cutting parameters, enabling the identification of the fines to chip transition zone. The effective cutting depth was determined based on specific energy variations, and subsequently, the effective limit was determined in the fines transition zone. The results showed that cutting depths lower than the critical value lead to the production of high fines under ductile failure mode. Also, the results obtained from assessing the performance of the two-dimensional fines space, predicated on cutting parameters, demonstrated that the developed model effectively evaluates the fines transition zone with a high level of accuracy. The results of this study can help in managing the fines production.