Why do drill bits have spirals or flutes?
Drill bits have spirals or flutes for several reasons but the main two are to remove chips or cut material and to help cool the bit. The spiral or flute controls the rate of removal. A fast spiral allows higher volumes of material to be removed with a slower cut and a slower spiral is used where higher speeds remove material quicker when cutting more dense materials. The cut material needs removed to ensure a cleaner cut, and to prevent clogging or galling the cutting edge or hole surface. The cutting edge of a twist drill bit is tempered to give it a sharper stronger edge. Heat can cause that tempered edge to soften and become dull shortening its usefulness. The spirals help dissipate the heat from the point. Another way heat is controlled at the cutting edge is slowing the drill and using cutting fluid.
