Impact of Grain Size on the Cerchar Abrasiveness Test

The Cerchar abrasiveness test is a common testing procedure for the prediction of tool wear but consistent and detailed recommendations of the testing procedure are inexistent until now. One point of disagreement is the required number of scratch tests per sample to obtain reliable results depending on the grain size of the samples. The focus of this work was to verify the influence of grain size on the number of required single examinations per sample. Grain size analyses were performed to get sum-curves of each tested rock sample. From the grain size data the median and the interquartile range of the grain sizes were calculated. CAI values after 5 and after 10 scratch tests were compared with the median and the interquartile-range of the grain size. No grain size dependency of the CAI deviation between 5 and 10 tests in the analysed range was observed.