... hard formations.YG614.9 2100 90.0 For coring crowns, electric coal drill bits, coal cutting picks, oil cone bits and ... well boring.YG814.7 2400 89.5 For coring crowns, electric coal drill bits, coal cutting picks, cone drill bits and ... -hard, hard and very hard formations. K20 High quality tungsten carbide strips for sand making machine the drawing and specifications Tungsten carbide wear ...