Geometry Parts of Twisted Drill:
Twist
drill has three principal parts
1. Drill point or dead center
2. Body
3. Shank.
Drill
axis is
the longitudinal line.
Drill
point is
the sharpened end of the drill body consisting of all that part which is shaped
to produce lips, faces and chisel edge.
Lip
or cutting edge is
the edge formed by the intersection of the flank and face
Lip
length is
the minimum distance between the outer corner and the chisel-edge corner of the
lip.
Parts of twisted drill
Face is that portion of the
flute surface adjacent to the lip on which the chip impinges as it is cut from
the work.
Chisel
edge is
the edge formed by the intersection of the flanks.
Flank is that surface on a drill
point which extends behind the lip to the following flute.
Flutes are the grooves in the
body of the drill, which provide lips, allow the removal of chips, and permit
cutting fluid to reach the lips.
Flute
length is
the axial length from the extreme end of the point to the termination of the
flutes at the shank end of the body.
Body is
that portion of the drill nomenclature, which extends from the extreme cutting
end to the beginning of the shank.
Shank is
that portion of the drill by which it is held and driven,
Heel is
the edge formed by the intersection of the flute surface and the body
clearance.
Body
clearance
is that portion of the body surface reduced in diameter to provide diametric
clearance.
Core
or web
is the central portion of the drill situated between the roots of the flute sand
extending from the point end towards the shank; the point end of the core forms
the chisel edge.
Lands are the cylindrically ground surfaces on the
leading edges of the drill flutes.