Coal drill tips: Grade: YC6 YC8 YC8C etc Complete specifications ... 14.8 ≥90.0 ≥2150For coring crowns, electronic coal drill bits, coal cutting picks, oil cone bits and scraping ... 8 ≥89.5 ≥2320For coring crowns, electric coal drill bits, coal cutting picks, cone drill bits and scraping knife bits, used in ... the buttons of small and medium sized bits to drill soft and medium hard formations.YC8C 14.7≥88 ...