Nomenclature of twist drill

 

Body 

It is the part of the drill without its shank and neck. Helical grooves are cut on the body of the drill. 

Shank

It is the part of the drill by which it is held and driven. The shank may be straight or taper. The shank of the drill can be fitted directly into the spindle or by a tool holding device. 

Tang 

The flattened end of the taper shank is known as tang. It is meant to fit into a slot in the spindle or socket. It ensures a positive drive of the drill.

Neck 

It is the part of the drill, which is diametrically undercut between the body and the shank of the drill. The size of the drill is marked on the neck.

Point 

It is the sharpened end of the drill. It is shaped to produce lips, faces, flanks and chisel edge. The point angle for a normal grade drill is 118 degree.

Lip 

It is the edge formed by the intersection of flank and face. There are two lips and both of them should be of equal length. 

Land 

It is the cylindrically ground surface on the leading edges of the drill flutes adjacent to the body clearance surface. 

Flutes 

The grooves in the body of the drill are known as flutes. Flutes form the cutting edges on the point. It allows the chips to escape and make them curl. It permits the cutting fluid to reach the cutting edge.