Document Type

Conference Paper

Publication Date


Publication Details

Esmat Sarwary and Paul Hagan, Changes in Cutter Performance with Tool Wear, 15th Coal Operators' Conference, University of Wollongong, The Australasian Institute of Mining and Metallurgy and Mine Managers Association of Australia, 2015, 283-290.


Mechanical excavators such as shearers, road-headers, and continuous miners that utilise conical picks are increasingly being used in civil construction and mining. Their application has broadened to include stronger and more abrasive rock types that result in higher wear rates and considerably shorter life span. This results in a bottleneck resulting in lower utilization and lower productivity. An understanding of the factors that cause high wear rates is crucial in the selection and design of an excavator, selection of cutter tools, and definition of optimum cutting geometry. All these parameters can contribute to major cost savings for companies using mechanical excavators. This paper explores how tool wear affects the cutting performance of a point attack pick with changes in the depth of cut. Linear rock cutting tests were performed using samples of Gosford Sandstone and Gambier Limestone at a constant speed of 0.06 m/s and pick attack angle of 55°. The rock samples were cut at depths ranging between 5 mm and 20 mm using a standard conical pick having tip angles of 70°, 90° 100° and 110°. The cutting forces and normal forces, specific energy, and yield were correlated against depth of cut. The results reveal that for each rock type, the specific energy increases at a decreasing rate with pick wear, confirming cutting efficiency decreases with increasing pick wear whereby a slight increase in pick wear resulted in a significant reduction in cutting efficiency. There was a near two to threefold decrease in efficiency between a sharp pick and worn out pick. The cutting and normal forces were also found to increase at a decreasing rate with pick wear.