Drill Tool Nomenclature:-
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| Drill Tool Nomenclature, Drill Tool Terminology |
The following are the twist drill elements:
Axis
The longitudinal centre line of the drill.
Body
The portion of the drill extending from its extreme point to the commencement of the neck,
if present, other
wise extending to the commencement of the shank.
if present, other
wise extending to the commencement of the shank.
Body clearance
That portion of the body surface which is reduced
in diameter to provide diametral clearance.
in diameter to provide diametral clearance.
Chisel edge
The edge formed by the intersection of the flanks.
The chisel edge is
also sometimes called
dead centre. The dead centre
or the chisel edge acts
as a flat drill and cuts its own hole in the workpiece.
The chisel edge is
also sometimes called
dead centre. The dead centre
or the chisel edge acts
as a flat drill and cuts its own hole in the workpiece.
Chisel
edge corner
The corner formed by the intersection
of a lip and the chisel edge.
of a lip and the chisel edge.
Face
The portion of the flute
surface adjacent to the lip on which
the chip impinges as it is cut from the work.
surface adjacent to the lip on which
the chip impinges as it is cut from the work.
Flank
That surface on a drill point which extends behind the lip tp the following
flute.
flute.
Flutes
The groove in the body of the drill which
provides lip. The functions of the flutes are:
provides lip. The functions of the flutes are:
To form the cutting
edges on the point
edges on the point
To allow the chips to escape
To cause the chips to curl
To permit the cutting fluid to reach the cutting
edges.
edges.
Heel
The edge formed by the intersection
of the flute surface and the body clearance.
of the flute surface and the body clearance.
Lands
The cylindrically ground
surface on the leading edges of the drill flutes.
The width of the land is measured at right angles to the flute helix.
The drill is full size only across
the lands at the point end. Land keeps
the drill aligned.
surface on the leading edges of the drill flutes.
The width of the land is measured at right angles to the flute helix.
The drill is full size only across
the lands at the point end. Land keeps
the drill aligned.
Lip (cutting
edge)
edge)
The edge formed by the intersection of the flank and face. The
requirements of the drill lips are: 1. Both lips should be at same angle of inclination
with the drill axis, 59o for general work
2. Both lips
should be of equal length
3. Both lips should
be provided with the correct
clearance.
requirements of the drill lips are: 1. Both lips should be at same angle of inclination
with the drill axis, 59o for general work
2. Both lips
should be of equal length
3. Both lips should
be provided with the correct
clearance.
Neck
The diametrically undercut portion between the
body and the shank of the drill. Diameter and other particulars of the drill are engraved
at the neck.
body and the shank of the drill. Diameter and other particulars of the drill are engraved
at the neck.
Outer corner
The corner formed
by the intersection of the flank and face.
by the intersection of the flank and face.
Point
The sharpened end of the drill, consisting of all that part of the drill which is
shaped to produce lips, faces,
flanks and chisel
edge.
shaped to produce lips, faces,
flanks and chisel
edge.
Right
hand cutting drill
hand cutting drill
A drill which cuts when rotating in
counter – clockwise direction viewed on the point end of the drill.
counter – clockwise direction viewed on the point end of the drill.
Shank
that part of the drill by which it is held and driven. The most common types
of shank are the taper
shank and the
straight shank. The taper shank
provides means of cantering and holding the drill by friction in the tapered
end of the spindle.
of shank are the taper
shank and the
straight shank. The taper shank
provides means of cantering and holding the drill by friction in the tapered
end of the spindle.
Tang
The flattened end of the taper shank intended to fit into a drift slot in the spindle, socket or drill holder. The tang ensures
positive drives of the drill
from the drill spindle.
positive drives of the drill
from the drill spindle.
Web:
The central portion of the drill situated between the roots of the flutes and
extending from the point toward the shank, the point end of the web or core forms the chisel edge.
The central portion of the drill situated between the roots of the flutes and
extending from the point toward the shank, the point end of the web or core forms the chisel edge.
The following are the linear
dimensions of the drill.
Back
taper
It is the reduction in diameter of the drill from
the point towards the shank.
the point towards the shank.
Body clearance
diameter
The diameter
over the surface
of the drill body which is
situated behind the lands.
over the surface
of the drill body which is
situated behind the lands.
Depth
of body clearance
of body clearance
The amount of radial reduction on each
side to provide body clearance.
side to provide body clearance.
Diameter
The
measurement across the cylindrical lands
at the outer corners of the drill.
measurement across the cylindrical lands
at the outer corners of the drill.
Flute length
The axial length
from the extreme
end of the point to the termination of the flute at the shank end of the body.
from the extreme
end of the point to the termination of the flute at the shank end of the body.
Lead
of helix
of helix
The distance measured parallel to the drill axis
between the corresponding point on the leading edge of the flute in one
complete turn of the flute.
between the corresponding point on the leading edge of the flute in one
complete turn of the flute.
Lip length
The minimum distance
between the outer corner and the chisel
edge corner of the lip.
between the outer corner and the chisel
edge corner of the lip.
Overall length
The length over the extreme
ends of the point and the shank of the drill.
ends of the point and the shank of the drill.
Web (core) taper
The increase in the web or core thickness from the point of the drill
to the shank end of the flute.
to the shank end of the flute.
Web thickness
The minimum dimension of the web or core measured at the point end of the drill.