A Drill bit, is a device attached to the end of the drill string

Drill string

A drill string on a drilling rig is a column, or string, of drill pipe that transmits drilling fluid and torque to the drill bit. The term is loosely applied as the assembled collection of the drill pipe, drill collars, tools and drill bit...

 that breaks apart, cuts or crushes the rock formations when drilling a wellbore

Wellbore

A wellbore is any hole drilled for the purpose of exploration or extraction of natural resources such as water, gas or oil where a well may be produced and a resource is extracted for a protracted period of time....

, such as those drilled to extract water, gas, or oil.

The drill bit is hollow and has jets to allow for the expulsion of the drilling fluid

Drilling fluid

In geotechnical engineering, drilling fluid is a fluid used to aid the drilling of boreholes into the earth. Often used while drilling oil and natural gas wells and on exploration drilling rigs, drilling fluids are also used for much simpler boreholes, such as water wells. Liquid drilling fluid...

, or "mud", at high velocity and high pressure to help clean the bit and, for softer formations, help to break apart the rock. A tricone bit comprises three conical rollers with teeth made of a hard material, such as tungsten carbide

Tungsten carbide

Tungsten carbide is an inorganic chemical compound containing equal parts of tungsten and carbon atoms. Colloquially, tungsten carbide is often simply called carbide. In its most basic form, it is a fine gray powder, but it can be pressed and formed into shapes for use in industrial machinery,...

. The teeth break rock by crushing as the rollers move around the bottom of the borehole. A polycrystalline diamond compact (PDC) bit has no moving parts and works by scraping the rock surface with disk-shaped teeth made of a slug of synthetic diamond attached to a tungsten carbide cylinder.

The tricone bit is an improvement on the original bit patented in 1909 by Howard R. Hughes, Sr.

Howard R. Hughes, Sr.

Howard Robard Hughes, Sr. was an American entrepreneur, best known as the father of Howard Robard Hughes, Jr., the famous aviation pioneer and film producer. Hughes, Sr. created the fortune that Hughes, Jr. inherited when he turned 18.-Early years:Hughes, Sr...

 of Houston, Texas

Houston, Texas

Houston is the fourth-largest city in the United States, and the largest city in the state of Texas. According to the 2010 U.S. Census, the city had a population of 2.1 million people within an area of . Houston is the seat of Harris County and the economic center of , which is the ...

, father of the famed billionaire Howard R. Hughes, Jr.

Howard Hughes

Howard Robard Hughes, Jr. was an American business magnate, investor, aviator, engineer, film producer, director, and philanthropist. He was one of the wealthiest people in the world...

.

PDC bits, first came into widespread use in 1976, used for gas and oil exploration the North Sea

North Sea

In the southwest, beyond the Straits of Dover, the North Sea becomes the English Channel connecting to the Atlantic Ocean. In the east, it connects to the Baltic Sea via the Skagerrak and Kattegat, narrow straits that separate Denmark from Norway and Sweden respectively...

. They are effective at drilling shale formations, especially when used in combination with oil-base drilling muds.