... in complex formations; with high quality PDC or hard alloy cutters, advanced welding technology, multiple precise heat treatment. ... 、Φ28mm、 Φ29mm、Φ32mm、 Φ34mm、Φ36mm、Φ40mm、Φ43mm.Hard Alloy anchor bit features:Is suitable for the drilling of coal ... , good performance in harsh working conditions. High quality tungsten carbide alloy insterts,advanced welding technology, multiple accurate heat treatment. ...