... ≥90.0 ≥2150For coring crowns, electronic coal drill bits, coal cutting picks, oil cone bits and scraping ... knife bits, applied in geological prospecting, coal mining and oil well boring. YC8 K30 14 ... ≥89.5 ≥2320For coring crowns, electric coal drill bits, coal cutting picks, cone drill bits and scraping ... used as the buttons of small and medium sized bits to drill soft and medium hard ...