... passed the ISO9000/2000 3.coal mining bits 1.We can supply all kinds of RUIZUAN brand coal mining bits, sleeves and ... mines, iron ores, aluminum ores, geotechnical engineering etc;3.We can design and produce different bits according to different hardness of ... , produce and repair all kinds of cutter drums.5.We can supply the following Bits and Holders:U82,U84,U85,U92,U94 ...