Percussion and rotary-percussion drilling are used in non-coring drilling operations for medium to hard rock; applications include exploration and blasting boreholes, and degassing shafts.

This type of drilling is used when a core is not needed for analysis. In percussion drilling, the main function is a pneumatic-force driven pounding tip, which produces a hammering action parallel to the drill hole angle (compressive force); whereas rotary-percussion drills include rotating drill bit for added shear force. Cuttings from the drill hole can be collected for analysis.

Figure: Percussion drills rely on a delivering rapid, powerful compressive forces to fracture and break rock in boreholes, while rotary-percussion drills also provide shearing force.

A rotary drill utilizes shear forces to fracture and penetrate solids. These drills may be used for collecting samples, creating blast holes, or holes for ventilation of underground mines; auger-type rotary drills can also be used for mining soft deposits like coal (auger mining). Rotary drills use a variety of very sharp drill bits to recover samples from the earth's crust.

Common rotary drill bits are shown in the figure below:

• Auger drill-useful for soil and soft rock/coal (left)
• Tri-cone drill –useful for drilling through medium and hard rock (middle)
• Diamond bit drill-useful for drilling core samples (right)

Figure: Different rotary drills can be used for specific mining operations.