Investigation into effect of scratch length and surface condition on Cerchar abrasivity index: Fid-Bau Portal

Investigation into effect of scratch length and surface condition on Cerchar abrasivity index

Yaralı, O. / Duru, H.

Highlights • 15mm scratch length should be used in CAI test instead of 10mm of scratch length. • It is suggested that the CAI test should be carried out on sawn cut surface. • It was recommended to employ stylus having a Rockwell Hardness HRC 54±1. • New classification systems for both rough and sawn cut surfaces are proposed.

Abstract The Cerchar abrasivity index (CAI) obtained from Cerchar abrasivity tests is an indicator of abrasiveness of rocks, and widely used for the estimation of bit/cutting tool life and wear rates in various mining and tunnelling applications. The effect of scratch length on CAI is investigated in this study by use of West apparatus and 6 different steel styluses with Rockwell Hardness of HRC40-42, HRC44-46, HRC48-50, HRC50-52, HRC54-56, and HRC58-60. The tests are carried out on 15 different rock samples (sedimentary, igneous, and metamorphic) on which rough and sawn cut surfaces with scratch lengths varying between 2mm and 20mm with an increment of 2mm, thus resulting in total 27,000 scratches. It is observed that the CAI values between 85% and 93% are reached at the sliding distance of 10mm while about the final CAI value of 99% is reached at 15mm. It is also observed that the CAI values on rough surfaces are about 18% higher than those on sawn cut surfaces. Besides, it is determined that the most suitable surface condition in CAI test is sawn cut surfaces according to the coefficient of variation of CAI values in measurement depending on the stylus hardness and the measurement surface condition.