K series bits are non-sealed roller bearing bits that are cooled and cleaned by air. The main structure features include:a. Utilizes carbide compacts of high strength and high toughness for increased impact strength and wear resistance while reducing compact breakage.b. Optimized number of compact rows, total number of compacts, compact exposure and shapes maximize the cutting ability and drilling speed of the bit.c. Adequately heat-treated bearing surface to increase the bearing capacity and service life.d. The thrust bearing can further increase the overall bearing capacity while improving the air circulation condition inside the bearing cavity, thus helpful for reducing the temperature in the cavity.e. The air-water separator can prevent water or formation cuttings from entering the bearing cavity through waterway or nozzles while supplying cooling air to the bearing.f. Strategically placed nozzles are advantageous to thoroughly clean the bottom hole, and the nozzle diameter can be selected according to specific air pressure and displacement.g. Optimum designed head shape provides maximum space for removing the cuttings off the bottom hole and also increases the penetration rate. Head OD is well protected by additional carbide compacts and special hard facing.h. By utilizing trimmer technology, K series mining bit can be combined into KT series bit.