Mining and Well Drilling Bits Information
Mining and well drilling bits are boring tools that drill through and penetrate soft and hard rock materials. They are used in mining, quarrying, tunneling, construction, well drilling, geological exploration, and blasting applications.
Mining and well drilling bits typically feature a threaded connection for attachment to a drill or drillstring and a hollow body through which drill fluids are circulated. Drill fluids are required to clear drill cuttings, cool the bit, and stabilize the borehole wall. Types of well drilling bits include the following:
Tri-cone or roller bits contain three toothed cones, each with a journal angle pitched towards the bit’s primary axis. The journal angle is modified according to the hardness of the formation. The teeth of each cone mesh against one another to bore through solid earth. The bit is driven by the weight-on-bit (WOB) while being pulled by the rotary action of the drill bit head.
Button bits are fixed-head bits that have conical or chisel bit inserts aligned in a matrix about the drill bit head. The head configuration of the bit may be convex, concave, or flat. Button bits with polycrystalline diamond compact (PDC) inserts may be referred to as PDC bits and are commonly used in directional drilling operations.
Cross bits and chisel bits are fixed-head bits that have hardened steel or carbide blades. Chisel bits are defined by a single blade while cross bits contain two or more blades that cross at the center of the bit. The blades are typically tapered down toward the cutting surface.
Anchor bits are commonly used in coal mining operations to drill pilot holes for the insertion of roof bolts. The roof bolts function to support roof rock and prevent cave-ins. Anchor bits are typically fixed-head winged bits and offer fast cutting action for drilling bore holes up to several feet long, ranging from a half-inch to an inch or more.
ISO 1717--Connection dimensions for rotary drill-rods and drill bits
Lilly M / CC BY-SA 3.0