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Table 1 Summary of rock removal performance parameters. Rock removal performance parameters for Rorschach sandstone (left) and Grimsel granite (right), evaluated under untreated and after-treatment material conditions

From: The influence of thermal treatment on rock–bit interaction: a study of a combined thermo–mechanical drilling (CTMD) concept

 SandstoneGranite
UntreatedAfter treatmentUntreatedAfter treatment
Removal rate  [mm3/min]9.9714.250.0461.362
Wear rate  [mm3/min]\(5.57\times 10^{-4}\)\(1.43\times 10^{-4}\)0.0150.028
Performance ratio  [−]\(1.79\times 10^{4}\)\(9.96\times 10^{4}\)3.0948.99
Specific energy  [J/mm3]0.440.2954.642.62