Effect of Pin Speed on Cerchar Abrasion Test Results

Abstract Abrasive properties of rocks affect tool selection and design of rock excavation machines as well as their productivity and operational costs. The Cerchar test is a simple and commonly used method of measuring rock abrasion. The current article focuses on the effect of pin sliding speed on the Cerchar abrasion index. For this study, Cerchar tests were conducted on seven mono-mineral rock samples with different pin speeds. The results showed that the variation of pin speed could affect the wear of the pin tip. However, the effect is not uniform and depends on the hardness of rocks and pins. The changes in the pin speed can change the pin penetration into the sample surface as well. Harder pins penetrate deeper into the sample surface. However, the difference between harder and softer pins decreases with an increase in pin speed. Pin tip penetration into the sample surface is not changed by its sliding speed in hard samples such as quartz. Accordingly, a new parameter was introduced: the ratio of the volume of rock removed by scratch to the volume of pin tip wear. This ratio is called scratch volume to wear ratio (SVWR) and is used to determine the optimum pin motion speed in various conditions. The optimum pin speed could also be used as a guide to determine the optimum speed of cutting tools on rock surfaces in practical conditions. A new abrasion classification system was introduced based on SVWR and showed that it could be used regardless of pin hardness.