The different parts of the drill bit are shown in Figure 19.30.
Figure 19.30 Drill Nomenclature
Flute: The helical groove in the drill body is known as flute. Its functions are to carry the chips, admit the coolant, make the chips to curl, and provide the cutting edges on the point.
Point: It is conical part of the drill; cutting lips are ground on the point.
Body: The part of the drill that is fluted and relieved is known as body.
Tang: The flattened end of the taper shank is known as tang. It helps to remove the drill from socket or sleeve from the spindle without injuring the shank.
Dead Centre: The point at which the two lips are properly ground and meet is known as dead centre.
Lips: The cutting edges of a drill are known as lips. Both lips should have equal length, same angle of inclination, and correct clearance.
Margin or Land: The narrow surface along the groove that determines the size of the drill and keeps the drill aligned is known as margin or land.
Web: The backbone of the drill of the narrow section between the flutes is known as web.
Heel: The edge which is formed by the intersection of the flute surface and the body clearance is known as heel.
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