... a variety of taper angles, generally, the light duty rock drill usually use 7 taper or smaller taper angle, the ... heavy duty rock drill mainly use 11,12 taper angle. And the ... usually. Regarding Integral drill steels,the quality of a steel material and a tungsten carbide is very important to ... in bundles.(6)Productivity: 20000pcs / month MAXDRILL rock drill steel rod