ABSTRACT
Rock drilling, in the field of blasting, is the first operation carried out and its purpose is to open holes, with the adequate geometry and distribution within the rock masses, where the explosive charges will be placed along with their initiating devices. Even though there is an enormous variety of possible rock drilling systems, in mining and civil engineering drilling is presently carried out, almost exclusively, by mechanical energy. Blasthole drilling is almost always carried out in rock masses. The principal physical rock properties that have influence upon penetration mechanisms and, as a consequence, on choice of the drilling method are: hardness, strength, elasticity, plasticity, abrasiveness, texture, structure, characteristics of breakage. The hardness of rocks is the principal type of resistance that must be overcome during drilling, because once the bit has penetrated, the rest of the operation is easier.
