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QUICK FACT GUIDES FOR MACHINISTS
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GUIDES
FUNDAMENTALS OF
DRILLING & TAPPING
FUNDAMENTALS
OF THREADING ON A LATHE
FUNDAMENTALS OF
WORKING BETWEEN CENTERS FUNDAMENTALS OF HEAT TREATING
FUNDAMENTALS
OF MILLING
FUNDAMENTALS
OF SAWING
METALWORKING
SHOP TERMS
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CARBIDE
INSERT TERMS: ABRASION
RESISTANCE: The
ability of a material to withstand a change in dimension due to a rubbing
action. ABRASIVE WEAR:
The wear that occurs on a tool in use due to the rubbing action in machining.
See Flank Wear. ANVIL (SEAT, SHIM): A
removable part of a toolholder designed to provide support for the cutting
insert. See Insert Package. ATTACK ANGLE (LEAD ANGLE, SIDE CUTTING EDGE ANGLE): Term
preferred by some to avoid confusion over the meaning of Side Cutting Edge
Angle. See Lead Angle. BACK RAKE (TOP RAKE):
The angle of inclination of the face of the tool away from the end cutting edge.
It is measured in a plane perpendicular to the base of the tool and parallel to
the side cutting edge. See Rake. BAR (BORING BAR):
A toolholder specifically designed to support cutting tools in a boring
operation. Deep-hole boring often requires a long, round (or
"bar-shaped") toolholder that is supported on one end. BUILDUP: See
Build Up Edge. BUILD UP EDGE:
An adhering deposit of work material on the tool face (rake face) adjacent to
the cutting edge. CHAMFER:
A bevel on the cutting edge of a cutting tool for the purpose of increasing its
strength. The angle is measured from the cutting face downward and will
generally vary from 25 to 45 degrees. CHIPBREAKER: A
groove or irregularity in the face of a tool, or a separate piece fastened to
the tool or toolholder, to cause the chip to break into short sections, or curl.
CHIPBREAKER INSERT:
An insert with a built-in chipbreaker. This generally consists of a groove
around the top face of the insert near the periphery. CHIPPING: The
breakdown of cutting edges by loss of fragments broken away during the cutting
action. CLEARANCE: The
angle below or behind the cutting edge, which allows the cutting-edge to be
forced into the work. Without clearance, the tool will not cut. It is also the
term used for secondary relief in some cases. See Relief. CRATER: A
grooved area or depression caused by chips rubbing-away or eroding a groove or
well in the top (the rake face) of the insert behind the cutting edge of a tool.
CUTTING EDGE: That
part of the face edge along which the chip is separated from the work. The
cutting edge consists of the side cutting edge, the nose, and the end cutting
edge. CUTTING SPEED: In
turning, the peripheral velocity of the workpiece at the cutting radius. It is
measured in surface feet per minute, sfm. DEFORMATION:
The permanent change in the shape of a cutting tool due to cutting forces and
temperature. This generally occurs in high-speed or heavy machining. DEPTH OF CUT: The
distance between the bottom of the cut and the uncut surface of the work,
measured in a direction at right angles to the machined surface of the work.
This is the difference in height between the machined and un-machined surfaces. EDGE PREPARATION:
A conditioning of the cutting edge, such as honing or chamfering. See
Chamfer, Honing. END CUTTING EDGE ANGLE: The angle between the cutting edge on the end of the tool and a line
perpendicular to the side edge of the straight portion of the tool shank. END RELIEF ANGLE:
Angle between the portion of the end flank immediately below the cutting edge
and a line drawn through that cutting edge at right angles to the base of the
toolholder. See Clearance, Relief. ENTRANCE ANGLE:
The angle that the side-cutting edge of a tool makes with the machined surface
of the work, measured on the cutting-edge side of the tool point. FACE (RAKE FACE):
That surface of the cutting tool on which the chip impinges as it is separated
from the work. FEED:
In turning, the distance moved by the tool into or along the work for each
revolution of the work. It is measured in inches per revolution, irp. FLANK: That
surface adjacent to the cutting edge and below it when the tool is in a
horizontal position for turning. FLANK WEAR (ABRASIVE WEAR): The wear that occurs along the flank of a tool, below and immediately
adjacent to the cutting edge, while cutting. This wear reduces the clearance
angle of the tool until failure finally occurs. See Wear Land. HEAT CHECK:
Many small cracks in the surface caused by grinding too rapidly, without proper
coolant, or with too much pressure during grinding. HONED: Abrasively
finished, generally by rubbing, using a wet compound and abrasives. HONING: The
process of rounding or blunting the cutting edge with abrasives for increased
edge strength. It may be done by hand or by machine. See Edge Preparation.
INCLUDED ANGLE:
A measurement of the total angle within the interior of a piece. The angle
between any two intersecting lines or surfaces. The corner angle of an insert. INSCRIBED CIRCLE (IC):
The circle that can be constructed internal to any closed figure or shape so
that all sides of the figure are tangent to the circle. The inscribed circle is
most often used to describe the dimensions of a triangle, pentagon, hexagon,
octagon, or trigon.
The IC of a square or parallelogram is equal to the perpendicular
distance between opposite sides, the IC of a round insert is the same as the
insert diameter. INSERT:
The cutting tip, made of hard material, that is mechanically applied to the
toolholder for use. It can generally be indexed to present more than one cutting
edge. INSERT PACKAGE:
The complete assembly that fits into the insert pocket of a toolholder. This
includes such components as a seat, setscrew, insert, chipbreaker, clamp, and
clamp screw. INSERT POCKET: The
space that has been machined out of a toolholder to receive the insert package
(seat, insert, chipbreaker, etc.) LAPPING: An
abrasive finishing process involving rubbing with a wet compound. Commonly used
to achieve a high degree of flatness on inserts. LEAD ANGLE (SIDE CUTTING EDGE ANGLE, ATTACK ANGLE): The
angle between the side cutting edge and the projected side of the tool shank or
holder, which leads the tool into the work. See Attack Angle. MACHINABILITY RATING: A
numerical value expressing the ease or difficulty of machining a particular
workpiece material in comparison with AISI B 1112 cold-rolled steel being turned
at 180 sfm, which is rated at 100 percent. NEGATIVE LAND (K-LAND): A bevel along the cutting edge causing the rake to become more negative.
It may range from 3 to 5 degrees and is measured off the top face of the insert.
See Chamfer. NEGATIVE RAKE:
A rake angle that is less keen or more blunt than zero rake. See Rake NEUTRAL RAKE:
A rake angle of zero degrees. This angle is perpendicular to the surface of the
work and neither positive or negative. See Rake. NOSE:
The corner angle formed by joining the side and end cutting edges of a tool. NOSE RADIUS: The
radius on the tool between the end and side cutting edges. PIN-TYPE-INSERT: An
indexable cemented-carbide cutting-tool insert with a hole in the center used to
locate the insert and clamp it in place by means of a pin in the toolholder. The
need for a top clamp is thus avoided. POCKET: See Insert Pocket. POSITIVE RAKE: A
rake angle that is keener or more acute than zero rake. See Rake. PRECISION INSERT: An
insert (Code G in the third position) that is ground on all surfaces to
specified dimension plus or minus 0.0012 inch on the cutting point and plus or
minus 0.005 inch on the thickness. See Super Precision Insert.
PREHONED:
Machined honed to a uniform size by the insert manufacture. See Honing. RAKE: The
angle of inclination between the face of the cutting tool and the work. If the
face of the tool lies in a plane through the axis of the work (on a round
workpiece), the tool is said to have zero, or neutral, rake. If the inclination
of the tool face makes the cutting edge keener or more acute than when the rake
angle is zero, the rake is defined as positive. If the inclination of the tool
face makes the cutting edge less keen or more blunt than when the rake angle is
zero, the rake is defined as negative. See Back Rake,
Side Rake. RAKE FACE: See
Face. RELIEF: The
clearance angle behind or below the cutting edge, allowing the cutting edge to
be forced into the work. It is sometimes divided into primary relief (adjacent
to the cutting edge) and secondary relief (beyond the primary relief.) Depends
on both the clearance angle of the insert and the insert attitude in the tool
holder. SEAT (ANVIL, SHIM): A
removable part of a toolholder, designed to support the cutting insert.
See Anvil, Insert Package. SFM (SURFACE FEET PER MINUTE): Peripheral velocity of the workpiece at cutting radius. See Cutting
Speed. SIDE CUTTING EDGE ANGLE LEAD ANGLE, ATTACK ANGLE):
The angle between the side cutting edge and the projected side of the shank or
holder. See Lead Angle. SIDE RAKE: The
inclination of the face of the tool away from the side cutting edge. It is
measured in a plane perpendicular to the top plane of the cutting edge. See
Rake. SIDE RELIEF ANGLE: The
angle between the side flank immediately below the side cutting edge and a line
drawn through the side cutting edge perpendicular to the base. SPEED (CUTTING SPEED, SURFACE SPEED): See Cutting Speed. SUPERPRECISION INSERT: An insert ground on all surfaces to closer tolerance than a precision
insert. There are several classes of superprecision inserts with tolerances on
the nominal point dimension ranging from plus or minus 0.0002 inch to plus or
minus 0.001 inch and, on thickness dimensions from plus or minus 0.001 inch to
plus or minus 0.005 inch. TOOLHOLDER:
A tool component that mechanically holds the insert and that, in turn, is
mechanically affixed to a tool-carrying component of the machine tool, such as a
turret. Loosely, a tool-shank for insert type lathe tooling. TOP RAKE (BACK RAKE):
The angle of inclination of the tool face away from the end cutting edge. It is
measured in a plane perpendicular to the base of the tool and parallel to the
side cutting edge. See Rake. TRANSVERSE RUPTURE STRENGTH: Breaking strength of a material in a standard bending test. Measured in
pounds per square inch (psi) in the U.S. Generally used as an indication of the
toughness of a cutting-tool material although certain limitations exist. For
example, the test is static and may not provide a good prediction of performance
in a dynamic cutting mode. UTILITY INSERT:
An insert (Code U in the third position) ground on the top and bottom surface
only, with a common tolerance of plus or minus 0.005 inch. WEAR LAND:
A flat area worn on the relieved flank face of the insert, below or behind the
cutting edge. The depth of wear affects size and finish, and the width of the
wear land is a good indicator for comparing insert performance or for
determining the proper time to change or index the tool. See Abrasive
Wear,
Flank Wear. WORKING ANGLE:
Those angles between tool and work that depend not only on the shape of the
insert but also on its position with respect to the work as determined by the
toolholder. ZERO RAKE (NEUTRAL RAKE): See Rake |
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Copyright © 2002 QUICK FACT GUIDES FOR MACHINISTS
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