|
|
| Abrasive |
A
substance such as finely divided aluminum oxide or silicon carbide used
for grinding (abrading) |
| Abrasive Water Jet
Machining |
A machining process where
high-pressure water containing an abrasive material is directed through the
workpiece. |
| Absolute programming |
A method of programming in which all coordinates in the program are
determined from a single origin. |
| Accuracy |
A measure of the conformity of the geometry produced to that described
by the drawing or file. |
| Acute angle |
An angle of less than 90
degrees. |
| Alignment |
The proper positioning or
state of adjustment of parts in relation to each other |
| Alloy |
A combination of two or
more substances |
| Aluminum oxide |
a.k.a. alumina (A1203).
Occurs in nature as corundum and is used extensively as an abrasive. Today
most aluminum oxide abrasives are manufactured. |
| Angular |
Having one or more angles;
measured by an angle; forming an angle. |
| Angular measure |
The means by which an arc
of a circle is divided and measured. This can be in degrees (360 degrees
in a full circle) |
| Angularity |
The quality or
characteristic of being angular. |
| Anneal |
A heat treatment in which
metals are heated and then cooled very slowly for the purpose of
decreasing hardness. Annealing is used to improve machinability and to
remove stress from weldments |
| Arbor |
A rotating shaft upon which
a cutting tool is fastened. Often used as a term for mandrel |
| As rolled |
when metals bars are hot
rolled and allowed to cool in air |
| Austenite |
A solid solution of iron
and carbon or iron carbide in which gamma iron |
| Axial |
Having the characteristics
of an axis (that is |
| Axial rake |
An angular cutting surface
that is rotated about the axial centerline of a cutting tool such as a
drill or reamer. |
| Axis
|
Centerline or center of
rotation of an object or part; the rotational axis of a machine spindle
which extends beyond the spindle and through the workpiece. Machining of
the object imparts the machine axis to that area of metal cutting. The
line along which a major machine tool component such as a mill table |
Backlash
|
A condition created due to
clearance between a thread and nut. The amount of thread turn before a
component begins to move. |
| Beam |
The scale on a vernier
caliper or height gage that is graduated in true or full sized units. |
| Bellmouth |
A condition in a machined
hole where the end is flared out in a bell shape to a dimension larger
than the nominal size of the hole. |
| Bezel |
A rim that holds a
transparent face of a dial indicator that can be rotated to bring the
index mark to zero. |
| Bimetallic |
Made from two different
metals. |
| Blind hole |
A hole that does not go
completely through an object. |
| Block |
All of the information contained in a single line of CNC machine code |
| Blotter |
A paper disk placed between
a grinding wheel and the retaining flange |
| Bore |
(1) A machined hole. (2)
The process of enlarging a drilled hole to a larger size. |
| Bore |
An operation and tool in which the single tool tip (similar to a lathe
tool) is offset radially from the axis of rotation by the radius of the
hole. The tool is rotated and
traversed axially to produce an accurately sized and round hole. |
| Boring |
The process of removing
metal from a hole by using a single-point tool. The workpiece can rotate
with a stationary bar |
| Brinell hardness |
The hardness of a metal or
alloy measured by hydraulically pressing a hard ball (usually 10 mm
diameter) with a standard load into the specimen. A number is derived by
measuring the indentation with a special microscope. |
| Broaching |
The process of removing
unwanted metal by pulling or pushing a tool on which cutting teeth project
through or along the surface of a workpiece. The cutting teeth are each
progressively longer by a few thousandths of an inch to give each tooth a
chip load. One of the most frequent uses of broaching is for producing
internal shapes such as keyseats and splines. |
| Buffing wheel |
A disk made up of layers of
cloth sewed together. Fine abrasive is applied to the periphery of the
cloth wheel to provide a polishing surface as the wheel is rotated at a
high speed. |
| Burnish |
To make shiny by rubbing.
No surface material is removed by this finishing process. External and
internal surfaces are often smoothed with high pressure rolling. Hardened
plugs are sometimes forced through bores to finish and size them by
burnishing. |
| Burr |
(1) A small rotary file.
(2) A thin edge of metal |
| Bushing |
A hollow cylinder that is
used as a spacer |
| Button die
|
A thread-cutting die that
is round and usually slightly adjustable. It is held in a diestock or
holder by means of a cone point setscrew that fits into a detent on the
periphery of the die. |
| Calibration |
The adjustment of a
measuring instrument such as a micrometer or dial indicator so it will
measure accurately. |
| Cam |
A rotating or sliding part
with a projection or projecting geometry that imparts motion to another
part as it slides or rotates past. |
| CAT 40 |
Short for Caterpillar is common for the ANSI B5.18 machine tool spindle
taper. |
| Cavity |
A machine feature |
| Center drill |
A preliminary drilling operation with a tool designed to produce an
extremely accurate starting location for subsequent operations. Rule of
thumb; hole depth ˜ hole diameter. |
| Centerline |
A reference line on a
drawing or part layout from which all dimensions are located. |
| Chamfer |
A bevel cut on a sharp edge
of a part to improve resistance to damage and as a safety measure to
prevent cuts. |
| Character |
A single alphanumeric value contained in a CNC program |
| Chasing |
a thread In machining
terminology |
| Chatter |
Vibration of workpiece |
| Checked |
A term used mostly in
grinding operations |
| Chip breaker |
An addition or modification
to a tool |
| Chips |
The particles that are
removed when materials are cut; also called filings. |
| Circularity |
The extent to which an
object has the form of a circle; the measured accuracy or roundness of a
circular or cylindrical object such as a shaft. A lack of circularity is
referred to in shops as out of round |
| Circumference |
The periphery or outer edge
of a circle. Its length is calculated by multiplying ~ (3.1416) times the
diameter of the circle. |
| Clutch |
A component usually found
in a mechanical drive that permits a driven component and driving
component to be mechanically disconnected and reconnected at will. |
| Coarseness |
A definition of grit size
in grinding or spacing of teeth on files and other cutting tools. |
| Coincident |
Two graduations on separate
graduated scales being in line with each other |
| Cold finish |
Refers to the surface
finish obtained on metal by any of several means of cold working |
| Cold working |
Any process such as rolling |
| Complementary angles |
Two angles whose sum is 90
degrees. Often referred to in machine shop work since most angular
machining is done within one quadrant or 90 degrees. |
| Concave |
An internal arc or curve; a
dent. |
| Concentricity |
The extent to which an
object has a common center or axis. Specifically |
| Contour Machining |
an uneven but continuous
path on a workpiece in two or three dimensions. |
| Convex |
An external arc or curve; a
bulge. |
| Coolant |
A cutting fluid used to
cool the tool and workpiece |
| Coordinate |
A method of specifying
point locations in a two dimensional plane system defined by two
perpendicular axes. |
| Copy mill |
|
| Cosine error |
A condition where the axis
of a measuring instrument is out of line with the axis of the measurement
to be taken |
| Counterbore |
A flat bottomed version of the countersink, to accommodate a cap screw
or bolt head. |
| Countersink |
Typically
an 82º included angle, the countersink produces a corresponding angled
hole to fit the countersunk, flathead screw. |
| Crest of thread |
Outer edge (point or flat)
of a thread form. |
| Critical temperatures |
The upper and lower
transformation points of iron between which is the transformation range in
which ferrite changes to austenite as the temperature rises. |
| Cutoff |
Uses a special grooving tool to separate the part from the remainder of
the stock material |
| Cutting fluid
|
Any of several materials
used in cutting metals: cutting oils |
| Deburr |
To remove a sharp edge or
corner caused by a machining process. |
| Degrees |
The circle is divided into
360 degrees |
| Diagonal |
A straight line from corner
to corner on a square |
| Diameter |
Twice the radius; the
length of any straight line going through the center of a figure or body;
specifically |
| Diametral pitch |
The ratio of the number of
teeth on gears to the number of inches of pitch diameter. |
| Die |
(1) Cutting tool for producing external threads. (2) A device that is
mounted in a press for cutting and forming sheet metal. |
| Die cast metal |
Metal alloys |
| Dimension |
A measurement in one
direction; one of three coordinates-length |
| Discrimination |
The level of measurement to
which an instrument is capable within a given measuring system. e.g. a
.001-in. micrometer can be read to within one thousandth of an inch. With
a vernier |
| Dovetail |
An angular shape used on
many types of interlocking slide components |
| Drill |
The most commonly known hole making tool. Most common is the jobber's length 118º point twist drill,
but there are very many variations. |
| Drive /Part |
|
| Ductility
|
The property of a metal to
be deformed permanently without rupture while under tension. A metal that
can be drawn into a wire is ductile. |
| Eccentricity |
A rotating member whose
axis of rotation is different or offset from the primary axis of the part
or mechanism. Thus |
| ECM |
a.k.a. Electrochemical
machining or electrochemical deburring (ECDB) |
| Edgefinder |
A tool fastened in a
machine spindle that locates the position of the workpiece edge in
relation to the spindle axis. |
| EDM |
a.k.a. Electrical-discharge
machining. In Plunge EDM a graphite or metal electrode is slowly fed into
the workpiece that is immersed in oil. A pulsed electrical charge causes
sparks to jump to the workpiece |
| Elasticity |
The property of a material
to return to its original shape when stretched or compressed. |
| Electrode |
A tool or other device used
to make an electrical contact such as the cutting tool in EDM machining
equipment. |
| ELG |
a.k.a. Electrolytic
grinding. A machining process in which an abrasive with a conducting bond
is used to deplate the workpiece material. |
| Endmill |
A
common rotating cylindrical cutting tool, with a maximum length to
diameter cutting ratio of between 2:1 and 4:1.
They get their name from the fact that they are capable of cutting
on the axial aspect of the cylinder, as well as the radial aspect. |
| Extruding
|
A form of metal working in
which a metal bar |
| Face |
(1) The side of a metal
disc or end of a shaft when turning in a lathe. A facing operation is
usually at 90 degrees to the spindle axis of the lathe. (2) The periphery
or outer cylindrical surface of a straight grinding wheel. |
| Face mill |
Milling on the uppermost surface of the part with the axial aspect of
the tool, generally a face mill. |
| Feed rate |
The rate at which the tool traverses the work, either in inches per
minute (mill) or thousandths of an inch per revolution of the spindle
(lathe). Affected by tool and
work variables such as material, rigidity, operation type. |
| Ferrous |
From the Latin word ferrum |
| Fillet |
(1) A concave junction of
two surfaces. (2) An inside corner radius of a shoulder on a shaft. (3) An
inside corner weld. |
| Finish bore |
Produces final geometry on the internal diameter of the part. |
| Finish face |
Produces the final geometry on the face of the part. |
| Finish turn |
The operation that produces the finished geometry on the outside
diameter of the part. |
| Finishing |
(surface) The control of
roughness by turning |
| Fixture |
A device that holds
workpieces and aligns them with the tool or machine axis with repeatable
accuracy. |
| Flash |
Excess material that is
extruded between die halves in die castings or forging dies; also |
| Flowline |
|
| Flute |
The groove in a drill |
| Forming
|
A method of working sheet
metal into useful shapes by pressing or bending. |
| Galling |
Cold welding of two metal
surfaces in intimate contact under pressure. Also called seizing |
| Gib |
A part of a slide mechanism
used to adjust the clearance between two sliding parts. |
| Glazing |
(1) A work-hardened surface
on metals resulting from using a dull tool or a too rapid cutting speed.
(2) A dull grinding wheel whose surface grains have worn flat causing the
work-piece to be overheated and "burned" (discolored). |
| Graduations |
Division marks on a rule |
| Graphite |
Carbon used as the material
for EDM electrodes. |
| Grit |
(1) Any small |
| Ground and polished |
(G & P) A finishing
process for some steel alloy shafts during their manufacture. The rolled |
| Gullet
|
The bottom of the space
between teeth on saws and circular milling cutters. |
| Hardenability |
The property that
determines the depth and distribution of hardness in a ferrous alloy
induced by heating and quenching. |
| Hardening |
Metals are hardened by cold
working or heat treating. Hardening causes metals to have a higher
resistance to penetration and abrasion. |
| Harmonic chatter |
A harmonic frequency is a
multiple of the fundamental frequency of sound. Any machine part. such as
a boring bar |
| Hazard |
A situation that is
dangerous to any person in the vicinity. Also |
| Heat treated |
Metal whose structure has
been altered or modified by the application of heat. |
| Helical |
The geometry of a helix
where a point both rotates and moves parallel to the axis of a cylinder.
Examples include threads |
| Helix |
The path described by a
point rotating about a cylinder while at the same time being moved along
the cylinder. The distance of movement compared to each revolution is the
lead of the helix. |
| High-pressure lube |
A petroleum grease or oil
containing graphite or molybdenum disulfide that continues to lubricate
even after the grease has been wiped off. |
| Hog |
To remove large amounts of
material from a workpiece with deep heavy cuts. |
| Hole Making |
A group of processes that produce one or more holes in a part for
various purposes. Examples
include drills, reamers, taps, etc. |
| Horizontal |
Parallel to the horizon or
base line; level. |
| Hot rolled |
Metal flattened and shaped
by rolls while at a red heat |
| Hub
|
A thickening near the axis
of a wheel |
| Increment |
A single step of a number
of steps; a succession of regular additions; a minute increase. |
| Incremental Programming |
Programming method in which each upcoming coordinate is specified
relative to the previous point coordinates. |
| Inert gas |
A gas |
| Infeed |
The depth a tool is moved
into the workpiece. |
| Interface |
The point or area of
contact between tool and workpiece; also the contact point or area of two
mating parts in an assembly. |
| Interference fit |
Force fit of a shaft and
bore |
| Internal stress |
a.k.a. residual stress
Stress in metals that is built in by heat treatment or by cold working. |
| Involute
|
Geometry found in modern
gears that permits mating gear teeth to engage each other with rolling
rather than sliding friction. |
| Jig |
A device that guides a
cutting tool and aligns it to the workpiece. |
| Journal
|
The part of a rotating
shaft or axle that turns in a bearing. |
| Kerf |
The width of a cut produced
by a saw. |
| Key |
A removable metal part that |
| Keysea |
t a.k.a. keyway An axially located rectangular groove in a shaft or hub. |
| Keystock |
Square or rectangular
cold-rolled steel bars used for making and fitting keys in keyseats. |
| Knurl
|
Diamond or straight
impressions on a metal surface produced by rolling with pressure. The
rolls used are called knurls. |
| Laminated |
Composed of multiple layers
of the same or different materials. |
| Laser |
An intense source of
coherent light energy that may be used as a cutting tool. |
| Lead |
The distance a thread or
nut advances along a threaded rod in one revolution. |
| Loading |
A grinding wheel whose
voids are being filled with metals |
| Lobe |
The offset or projection on
a cam that contacts the part to which motion is to be imparted. |
| Longitudinal
|
Lengthwise |
| Machinability |
The relative ease of
machining |
| Malleability |
The ability of a metal to
deform permanently without rupture when loaded in compression. |
| Mandrel |
A cylindrical bar upon
which the workpiece is affixed and subsequently machined between centers.
Mandrels |
| Manual |
Establishes an option for the operator to produce geometry outside of
computer control. |
| Manual |
Allows a manual intervention by the machine operator. Rarely Used. |
| Manual Volume Clear |
A rarely used option that allows the machine operator to manually remove
the bulk of material, or to program the material removal by other methods. |
| Mar |
To scratch or otherwise
damage a machined surface. |
| Metal spinning |
A process in which a thin
disc of metal is rapidly turned in a lathe and forced over a wooden form
or mandrel to form various conical or cylindrical shapes. |
| Metallizing |
Applying a coating of metal
on a surface by spraying molten metal on it. Also called spray weld and
metal spray. |
| Metrology |
The science of weights and
measures or measurement. |
| Milling |
Operations performed on a milling machine in which the tool is rotated
and the work stays relatively stationary |
| Mode |
A particular way in which
something is done or a machine is operated |
| Mushroom head
|
(1) An oversized head on a
fastener or tool that allows it to be easily pushed with the hand. (2) A
deformed striking end of a chisel or punch that should be removed by
grinding. |
| Neutral |
In machine work |
| Nominal |
Usually refers to a
standard size or quantity as named in standard references. |
| Nonferrous |
Metals other than iron or
iron alloys; for example |
| Normalizing |
A treatment consisting of
heating to a temperature above the critical range of steel followed by
cooling in air. Normalizing produces in steel a "normal
structure" consisting of free ferrite and cementite or free pearlite
and cementite |
| Nose radius
|
Refers to the rounding of
the point of a lathe cutting tool. A large radius produces a better finish
and is stronger than a small one. |
| Obtuse angle |
An angle greater than 90
degrees. |
| Orthographic drawing |
Projections of a single
view ofan object in which the view is projected along lines perpendicular
to both the view and the drawing surface. |
| Oxide scale |
At a red heat |
| Oxidize |
To combine with oxygen; to
burn or corrode by oxidation. |
| Oxyacetylene
|
Mixture of oxygen and
acetylene gases to produce an extremely hot flame used for heating and
welding. |
| Parallax error |
An error in measurement
caused by reading a measuring device |
| Parallel |
The condition in which
lines or planes are equidistant from each other. |
| Parting |
a.k.a. cutting off a lathe
operation in which a thin blade tool is fed into a turning work-piece to
make a groove that is continued to the. center to sever the material. |
| Pecking |
A process used in drilling
deep holes to remove chips before they can seize and jam the drill. The
drill Is fed into the hole a short distance to accumulate some chips in
the flutes and then drawn out of the hole |
| Pedestal |
A
base or floor stand under a machine tool. |
| Penetrant |
A thin liquid that is able
to enter small cracks and crevices. Penetrant oils are used to loosen
rusted threads; dye penetrants are used to find hidden cracks. |
| Periphery |
The perimeter or external
boundary of a surface or body. |
| Perpendicular |
At 90 degrees to the
horizontal or base line. |
| Pin Straight |
tapered |
| Pinion |
The smaller gear of a gear
set |
| Pinning |
A condition where chips of
workpiece material jam in the teeth of a file. |
| Pitch |
In saw teeth |
| Pitch diameter |
For threads |
| Plasma beam machining |
A machining process where a
very high-temperature gas (plasma) is used as the cutting tool. Plasma
arcs are very effective for cutting materials in sheet form. |
| Plunge mill |
An operation in which an endmill is plunged axially into the workpiece
at a given rate (typically 1/2 the radial federate) to produce a location
from which to begin cutting at that depth in the X-Y plane. |
| Post Processor |
A small program done within the CAM software that converts the general
machining instructions developed by the CAM program and programmer to the
detailed and machine specific G and M code required to operate the
machine. |
| Pot metals |
Die-casting alloys |
| Precipitation hardening |
A process of hardening an
alloy by heat treatment in which a constituent or phase precipitates from
a solid solution at room temperature or at a slightly elevated
temperature. |
| Precision |
A relative but higher level
of accuracy within certain tolerance limits. Precision gage blocks are
accurate within a few millionths of an inch |
| Pressure |
Generally expressed in
units as pounds per square inch (psi) |
| Profile |
An outline view |
| Profile |
Generally a finishing operation, causes the tool to follow the contours
of the part to produce the part geometry. |
| Proportion |
An equality of two ratios. |
| Prototype |
A full-scale original model
on which something is patterned. |
| Pulley
|
A flat-faced wheel used to
transmit power by means of a flat belt. Grooved pulleys are called
sheaves. |
| Quench |
A rapid cooling of heated
metal for the purpose of imparting certain properties |
| Quench cracking |
Cracking of heated metal
during the quenching operation caused by internal stresses. |
| Quick-change gearbox |
A set of gears and selector
levers by which the ratio of spindle rotation to lead screw rotation on a
lathe can be quickly set. Many ratios in terms of feeds or threads per
inch can be selected without the use of change gears. |
| Quick-change tool post |
A lathe toolholdlng device
In which preset cutting tools are clamped in tool-holders that can be
placed on the tool post or interchanged with others to an accurately
repeatable location. |
| Quill
|
The nonrotating but
retracting and extending portion of a drill press or milling machine
containing the bearings and machine spindle. |
| Radial |
Radiating outward from the
center. |
| Radial rake |
On cylindrical or circular
cutting tools |
| Radian |
A unit of angular
measurement that Is equal to the angle at the center of a circle subtended
by an arc equal in length to the radius. |
| Radius |
On a circle |
| Rake |
A tool angle that provides
a keenness to the cutting edge. |
| Rapid traverse |
A rapid-travel arrangement
on a machine tool used to quickly bring the workplece or cutting tool Into
close proximity before the cut Is started. |
| Recessing |
Grooving. |
| Reciprocating |
A movement back and forth
along a given axis. |
| Reference point |
On a layout or drawing |
| Relief angle |
An angle that provides
cutting edge clearance for the cutting action. |
| Right angle |
A 90-degree angle. |
| Ring test |
A means of detecting cracks
in grinding wheels. The wheel is lightly struck and |
| Rockwell |
A hardness test that uses a
penetrator and known weights. Several scales are used to cover the very
soft to the very hard materials. The Rockwell C scale is mostly used for
steel. |
| Root |
The bottom of a thread or
gear tooth. |
| Root truncation |
The flat at the bottom of a
thread groove. |
| Rough bore |
Similar to the rough turn, but done to internal diameter of the part. |
| Rough face |
Similar to the rough turn but accomplished with cuts parallel to the
face (perpendicular to the axis of rotation) |
| Rough groove |
Used to produce the rough geometry of internal or external grooves in a
part |
| Rough turn |
Removes the majority of material excess to the finished part, generally
in a series of cuts of smaller and smaller diameter.
Leaves a small amount of material for finishing operations |
| Roughing |
In machining operations |
| RPM |
Revolutions per minute. |
| RPM |
Revolutions per minute. Calculated
by (4*SFPM)/ rotational diameter. |
| Runout
|
An eccentricity of rotation
as that of a cylindrical part held in a lathe chuck being off center as It
rotates. The amount of runout of a rotating member Is often checked with a
dial indicator. |
| Scriber |
A sharp-pointed tool used
for making scratch marks on metal for the purpose of layout. |
| Sector |
A portion of a circle
between two rays defining a specific angle. |
| Seize |
A condition where two metal
parts are pressed together without the aid of lubrication |
| Semiprecision |
Using a method of layout |
| Serrated |
Small grooves |
| Set |
The width of saw tooth. The
set of saw teeth is wider than the blade width. |
| Setup |
The arrangement by which
the machinist fastens the workplece to a machine table or work-holding
device and aligns the cutting tool for metal removal. A poor setup Is said
to be when the workplece could move from the pressure of the cutting tool |
| sfm or sfpm |
Surface feet per minute on
a moving workplece or tool. |
| Shank |
The part of a tool that is
held in a work-holding device or in the hand. |
| Shearing |
(1) A concentration of
forces in which the bending moment Is virtually zero and the metal tends
to tear or be cut along a transverse axis at the point of applied
pressure.(2) The process by which (1) is used to cut metal |
| Sheaves |
Grooved pulleys such as
those used for V-belts or cables. |
| Shim |
A thin piece of material
used to take up space between workplece and work-holding device: a piece
used to fill space between machinery and foundations in assemblies. |
| SI |
Systeme International. The
metric system of |
| Silicon carbide |
A manufactured abrasive.
Silicon carbide wheels are used for grinding nonferrous metals |
| Sine bar |
A small precision bar with
a given length (5 or 10 in.) that remains constant at any angle. It is
used with precision gage blocks to set up or determine angles within a few
seconds of a degree. |
| Sintering |
Holding a compressed metal
powder briquette at a temperature just below its melting point until it
fuses into a solid mass of metal. |
| Slot |
Groove or depression as in
a keyseat slot. |
| Snagging |
Rough grinding to remove
unwanted metal from castings and other products. |
| Soluble oils |
Oils that have been
emulsified and will combine with water. |
| Solution heat treating |
See Precipitation
hardening. |
| Solvent |
A material |
| Spark testing |
A means of determining the
relative carbon content of plain carbon steels and identifying some other
metals by observing the sparks given off while grinding the metals. |
| SPC |
a.k.a. Statistical Process
Control. The methods and tools used to determine the results of a
manufacturing process by recording and graphing part dimensions and then
generating various statistical Information about the results. |
| Specifications |
Requirements and limits
for a particular job. |
| Speeds |
Machine speeds are
expressed in revolutions per minute; cutting speeds are expressed in
surface feet per minute. |
| Sphericity |
(1) A condition of
circularity in all possible axes. (2) The quality of being in the shape of
a ball. (3) The extent to which a true sphere can be produced with a given
process. |
| Spindle |
The portion of a machine tool that rotates the tool or work piece at the
specified RPM |
| Spiral |
A path of a point in a
rotating plane that is continuously receding from the center is called a
flat spiral. The term spiral is often used |
| Spline |
A shaft 6n which teeth have
been machined parallel to the shaft axis that will engage similar internal
teeth in a mating part to prevent turning. |
| Spot face |
Essentially a counterbore of minimal depth, used to produce a small
machined spot on a casting, forging, or other imperfect surface for
accurate location and fit of a fastener or locating device. |
| Sprockets |
Toothed wheels used with
chain for drive or conveyor systems. |
| Squareness |
The extent of accuracy
that can be maintained when making a workpiece with a right angle. |
| Stepped shaft |
A shaft having more than
one diameter. |
| Stick-slip |
A tendency of some machine
parts that slide on ways to bind slightly when pressure to move them is
applied |
| Straightedge |
A comparison measuring
device used to determine flatness. A precision straightedge usually has an
accuracy of about plus or minus .0002 In. in a 24-in. length. |
| Strength |
The ability of a metal to
resist external forces. This can be tensile |
| Stress |
An external force applied
to an object. |
| Stress relief anneal |
A heat treatment |
| Stroke |
A single movement of many
movements |
| Surface plate |
A cast iron or granite
surface having a precision flatness for precision layout |
| Surface speed (SFPM) |
A initial value for the linear velocity interaction between cutting tool
and work piece. Variables
affecting this value are tool and work materials, operation types, etc. |
| Symmetrical |
Usually bilateral in
machinery where two sides of an object are alike but usually as a mirror
image. |
| Synthetic oils
|
Artificially produced oils
that have been given special properties such as resistance to high
temperatures. Synthetic water soluble oils or emulsions are replacing
water soluble petroleum oils for cutting fluids and coolants. |
| Tang |
The part of a file on which
a handle Is affixed. |
| Tap |
The tool and operation to produce threaded holes for use with bolts and
screws. This shop is best
equipped to produce SAE (non-metric) threads. |
| Tap extractor |
A tool that is sometimes
effective in removing broken taps. |
| Tapered thread |
A thread made on a taper
such as a pipe thread. |
| Tapping |
A method of cutting
Internal threads by means of rotating a tap into a hole that Is
sufficiently under the nominal tap size to make a full thread. |
| Telescoping gage |
A transfer type tool that
assumes the size of the part to be measured by expanding or telescoping.
It is then measured with a micrometer. |
| Temper |
(1) The cold worked
condition of some nonferrous metals. (2) Also called draw |
| Template |
A metal |
| Tensile strength |
The maximum unit load that
can be applied to a material before ultimate failure occurs. |
| Tension |
A stretching or pulling
force. |
| Terminating threads |
Methods of ending the
thread |
| Test bar |
A precision ground bar that
is placed between centers on a lathe to test for center alignment using a
dial indicator. |
| Thermal cracking |
Checking or cracking caused
by heat. |
| Thread |
Creates internal or external threads using a single point threading
tool. |
| Thread axis |
The centerline of the
cylinder on which the thread is made. |
| Thread chaser |
A tool used to restore
damaged threads. |
| Thread crest |
The top of the thread. |
| Thread die |
A device used to cut
external threads. |
| Thread engagement |
The distance a nut or
mating part is turned onto the thread. |
| Thread fit |
Systems of thread fits for
various thread forms range from interference fits to very loose fits;
extensive references on thread fits may be found in machinist's handbooks. |
| Thread lead |
The distance a nut travels
in one revolution. The pitch and lead are the same on single lead threads
but not on multiple lead threads. |
| Thread pitch |
The distance from a point
on one thread to a corresponding point on the next thread. |
| Thread relief |
Usually an internal groove
that provides a terminating point for the threading tool. |
| T-nut |
A threaded nut in a T shape
that Is designed to fit into the T-slot on a machine tool table. |
| Tolerance |
The allowance of acceptable
error within which the mechanism will still fit together and be totally
functional. |
| Tool geometry |
The proper shape of a
cutting tool that makes it work effectively for a particular application. |
| Tooling |
Generally any machine tool
accessory separate from the machine itself. Tooling includes cutting tools |
| Toolmaker |
An experienced general
machinist often involved with high precision work making other tools |
| Torque |
A force that tends to
produce rotation or torsion. Torque is measured by multiplying the applied
force by the distance at which it is acting to the axis of the rotating
part. |
| Toxic fumes |
Gases resulting from
heating certain materials are toxic |
| Transfer measurement |
A step in measurement In
which a transfer measuring tool such as a telescoping gage is set to the
unknown dimension and subsequently measured with a direct measuring tool
such as a micrometer. |
| Traverse |
To move a machine table or
part from one point to another. |
| Trueing |
In machine work, making the
part or part feature more closely aligned with a given standard |
| Truncation |
To remove the point of a
triangle (as of a thread) |
| T-slot |
The slot in a machine tool
table |
| Tungsten carbide |
An extremely hard compound
that Is formed with cobalt and tungsten carbide powders by briquetting and
sintering Into tool shapes. |
| Turning
|
Machine operations in which
the work Is rotated against a single point tool. |
| Ultrasonic machining |
A machining process where
high-intensity sound (above 20 KhZ) is used to propel abrasive as a
material removal tool. |
| User defined |
Allows the user to define a custom hole making cycle to suit specific
needs. Not for the
inexperienced user. |
| Vernier |
A means of dividing a unit measurement on a graduated scale by means of
a short scale made to slide along the divisions of a graduated instrument. |
| Vibration |
An oscillating movement
caused by loose bearings or machine supports |
| Vise |
A workholdlng device. Some
types are bench |
| Vise |
A common fixturing method that clamps the work piece between a fixed jaw
and a movable one. Properly
set up, provides very fast exchange of parts for repetitious jobs. |
| Volume clear
|
A rough machining operation to remove the bulk of material prior to
finishing operations. |
| Weights and measures. |
|
| Wheel dressing |
Sharpening the grinding
surface of an abrasive wheel by means of a dressing tool such as a diamond
or Desmond dresser. |
| Word |
Letters within a CNC program with specific meaning to the CNC machine
control such as the "S-word" meaning spindle speed. |
| Wrought |
Hot or cold worked; forged. |
| Zero back rake |
a.k.a. neutral rake neither
positive nor negative; level. |
| Zero index
|
a.k.a. zero point. The
point at which the position displays machine are set to zero and the
cutting tool is located to a given reference |
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