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QUICK FACT GUIDES FOR MACHINISTS
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GUIDES |
GRINDING TERMS:
ACCURACY:
Conformity
in dimension to an exact standard. ALUMINA:
Un-fused
Aluminum Oxide. ALUMINUM
OXIDE: An
abrasive made by fusing the mineral Bauxite. ARBOR:
The spindle of the grinding machine on which the wheel is mounted. ARBOR
HOLE: The
hole in a grinding wheel sized to fit the machine arbor. ARC
OF CONTACT:
That portion of the circumference of a grinding wheel in contact with the work
being ground. ARKANSAS
OILSTONES:
A natural stone quarried in the Ozark Mountains and produces the finest cutting
edges. BALANCED
(Dynamic): A piece in static balance is in dynamic balance, if, upon rotating,
there is no vibration on or "whip" action due to unequal distributing
of its weight throughout its length. BALANCE
(Static):
A grinding wheel is in static balance when, centered on a frictionless
horizontal arbor, it remains at rest
in any position. BALANCING:
Testing for balance, adding or subtracting weight to put a piece into either
static or dynamic balance. BAUXITE:
A mineral ore high in aluminum oxide content, from which Alundum abrasive is
manufactured. BEARING:
Point of supports. The part of a machine in which the spindle revolves. BENCH
STAND: An
off-hand grinding machine, mounted either one or two wheels mounted on a
horizontal spindle, attached to a bench. BLOTTER:
A
disc of compressible material usually of blotting paper stock, used between a
wheel and flanges when mounting a grinding wheel. BOND:
The
material in a grinding wheel which holds the abrasive grains together. BORON
CARBIDE:
Next to diamonds, the hardest material ever made commercially by man. BRICK:
A block of bonded abrasive used for such purposes as rubbing down castings,
scouring castings, general foundry and machine shop use, scouring chilled iron
rolls, polishing marble, and work of like nature. BRINNELL
HARDNESS TESTER: A
machine used for testing the indentation hardness of metals except very hard
ones like tool steel. BURNING
(The Work): A
change in the work being ground caused by the heat of grinding, usually
accompanied by surface discoloration. BURR:
A
turned over edge of metal resulting from punching a sheet and sometimes from a
grinding or cut-off operation. BURRING
(pulpstone): Passing over
the face of a pulpstone with a special tool to develop a pattern to provide a
free cutting surface. BUSHING:
The
material, usually lead, babbitt or aluminum, which sometimes serve as a lining
for the hole in a grinding wheel. CENTER
HOLE LAPPING: The
cleaning or lapping of center holes with a bonded abrasive wheel cemented into a
steel mandrel. To present a clean surface for a dead center. CENTERLESS
GRINDING: Grinding
the outside or inside diameter of a round piece not mounted on centers. CENTERS:
Conical
steel pins of a grinding machine upon which the work is centered and rotated
during grinding. CHATTER
MARKS: Surface
imperfections on the work being ground, usually caused by vibrations between the
wheel and the work. CHUCK:
A
device for holding grinding wheels of special shape or the work piece being
ground. COATED
ABRASIVE:
Paper or cloth having abrasive grains bonded onto the surface. COLLETS:
See Flanges. CONE
WHEEL:
A small wheel shaped like a bullet nose which is used for portable grinding. CONTROLLED
STRUCTURE: The
process of manufacturing grinding wheels whereby the relationship between the
abrasive and bond is definitely controlled. COOLANT:
The liquid or solution used to cool the work and to prevent it from rusting. COPING:
Sawing
stone with a grinding wheel. CORNER
WEAR: The
tendency of a grinding wheel to wear on a corner so that it does not grind sharp
corners without fillets. CORUNDUM:
A natural abrasive of the aluminum oxide type, of higher purity then emery. CRANK
WHEEL:
An expression used to designate wheels for grinding crankshafts. CRITICAL
SPEED: Every
spindle or mandrel with a wheel or point mounted on it has a certain critical
speed at which vibration due to deflection or whip tends to become excessive. CRUSH
TRUING (OR FORMING): The
process of using steel rolls to true or form grinding wheels to a wide variety
of shapes. CRYSTAL:
A
solid symmetrical particle, bounded by plane surfaces. CRYSTALLINE:
Made up of crystals. CRYSTALLIZE:
To
convert into crystals. CUP
WHEEL:
A grinding wheel shaped like a cup or bowl. CUTTERS:
The
part of a grinding wheel dresser that comes in contact with the wheel and does
the cutting. CUTTING-OFF
WHEEL:
A thin wheel, usually made with an organic bond, for cutting off material. CUTTING
RATE: The
amount of material removed by a grinding wheel per unit of time. CUTTING
SURFACE: The
surface or face of the wheel against which the material is ground. CYLINDER
WHEEL:
A grinding wheel of similar characteristics to a straight wheel but with larger
hole size in proportion to its diameter and usually of several inches height. CYLINDRICAL
GRINDING:
Grinding the outside surface of a cylindrical part mounted on centers. DIAMOND
TOOL: A
diamond dresser. DIAMOND
WHEEL:
A grinding wheel in which the abrasive is mined or manufactured diamond. DISC
GRINDER:
A machine on which abrasive discs are used for grinding. DISC
WHEEL: A
grinding wheel shaped similar to a straight wheel, but usually mounted on a
plate and using the side of the wheel for grinding. DISCOLORATION:
See
Burning (The Work). DISH
WHEEL: A
wheel shaped like a dish. DOG:
A
device attached to the workpiece by means of which the work is revolved. DRESSERS:
Tools used for dressing a grinding wheel. DRESSING:
A
grinding wheel is dressed to improve or alter its cutting action. EMERY:
A natural abrasive of the aluminum oxide type. EXTERNAL
GRINDING: Grinding
on the outside surface of an object as distinguished from internal grinding. FACE:
That
part of a straight wheel on which cylindrical and surface grinding is usually
done. FEED,
CROSS: Surface
grinding. The distance of horizontal feed of the wheel across the table. FEED,
DOWN: Surface
grinding. The rate at which the abrasive wheel is fed into the work. FEED,
INDEX: Cylindrical
grinding. Measurement indicated by the index of the machine. On most machines
this measurement refers to the diameter of the work; on a few, to the radius. FEED
LINES:
A pattern on the work produced by grinding. The finer the finish the finer and
more evident are these lines. Some types of feed lines indicate incorrect
grinding conditions. FINISH:
The surface quality or appearance, such as that produced by grinding or other
machining operations. FLANGES:
The
circular metal plates on a grinding machine used to drive the grinding wheel.
See Wheel Sleeves. FLARING
CUP:
A cup wheel with the rim extending from the back at an angle so that the
diameter at the outer edge is greater than at the back. FLOOR
STAND GRINDERS:
An offhand grinder, mounting either one or two wheels running on a horizontal
spindle fixed to a metal base attached to the floor. FREEHAND
GRINDING:
Grinding by holding the work against the wheel by hand, usually called offhand
grinding. GENERATED
HEAT: Heat
resulting from the removal of metal by a grinding wheel. GLAZING:
The dulling of the cutting particles of a grinding wheel resulting in a
decreased rate of cutting. GLAZED
GRINDING WHEEL: A wheel is
"glazed" when the cutting particles have become dull or worn
down even
with the bond,
when the bond is so hard that the
abrasive
grains are
not dislodged when too dull to cut effectively. Glazing may indicate
either that the wheel is too hard for the work, or that the wheel speed is too
high. The remedy, then, for glazing is to decrease the speed or use a softer
wheel GRADE:
The
strength of bonding of a grinding wheel, frequently referred to as its hardness.
GRAIN:
Abrasive classified into predetermined sizes for use in polishing, in grinding
wheels and in coated abrasives. GRAIN
SIZE: The
size of the cutting particles of a grinding wheel or polishing abrasive. GRINDING
SPACING:
The relative position of the cutting particles in a grinding wheel. GRINDING:
Removing material with a grinding wheel. GRINDING
ACTION: Refers
to the cutting ability of, and finish produced by, a grinding wheel. GRINDING
MACHINES:
Any machine on which a grinding wheel is operated. GRINDING
WHEEL: A
cutting tool of circular shape made of abrasive grains bonded together. GRINDSTONE:
A flat, circular grinding wheel cut from natural sandstone sometimes used for
sharpening tools. HAND
GRINDING: See
Offhand Grinding. HEMMING
MACHINES:
Machines used for grinding flat surfaces such as cutlery blades and skates,
named after the inventor Mr. C. H. Hemming. HONING:
An abrasive operation typically performed on internal cylindrical surfaces and
employing bonded abrasive sticks in a special holder to remove stock and obtain
surface accuracy. HOODS:
Metal guards used for protection against wheel breakage. HUNTINGTON
DRESSER:
A tool using star shaped cutters for truing and dressing grinding wheels,
invented by a man named Huntington. INSERTED
NUT: Disc,
segment or cylinder wheels having nuts embedded in the back surface for mounting
on the machine. INTERNAL
GRINDING: Grinding
the inside surface of the hole in a piece of work. LAPPING:
A finishing process typically employing loose abrasive grains but now often
including similar types of operations with bonded abrasive wheels or coated
abrasives. LOADED
GRINDING WHEEL:
A grinding wheel is "loaded" when the pores or interstices between the
cutting particles are partly or entirely clogged with the material being ground.
Loading prevents the wheel from cutting and causes excessive heat to be
generated. If a wheel becomes loaded, the bond may be too hard or the speed too
slow. The remedy for loading is to increase the speed or use a softer wheel. LOADING:
Filing of the pores of the grinding wheel surface with the material being
ground, usually resulting in a decrease in production and poor finish. LUBRICANT:
The
liquid or solution used to lubricate the wheel and promote a more efficient
cutting action. MANDREL:
A solid cylindrical metal core, around
which abrasive material (grinding wheel) is mounted. MOUNTED
WHEELS: Small
bonded abrasive shapes and wheels that are mounted on steel mandrels. MOUNTING:
Putting a grinding wheel on
the arbor or spindle of the machine. NATURAL
ABRASIVE: A
hard mineral found in nature. See Abrasive. OFFHAND
GRINDING: Where
the work is held in the operator's hand, otherwise known as freehand grinding. OILSTONE:
A natural or manufactured abrasive stone impregnated with oil and used for
sharpening keen edged tools. OPERATION
SPEED:
The speed of revolution of a grinding wheel expressed in either revolutions per
minute or surface feet per minute. ORGANIC
BOND:
A bond made of organic materials such as the synthetic resins, rubber or
shellac. PERIPHERAL
SPEED:
The speed at which any point or particle of the face of the wheel is traveling
when the wheel is revolved, expressed in surface feet per minuet (s.f.m.)
Multiply the circumference in feet by the revolutions per minute. PERIPHERY:
The
line bounding a rounded surface, the circumference of a wheel. PLANER
TYPE: A
type of surface grinding machine built similar to an open side planer. PLATE
MOUNTED: Disc,
segment or cylinder wheels cemented to a steel back plate having projection
studs or other means for mounting on the machine. POLISHING:
Act
of smoothing off the roughness or putting a high finish on metal by applying a
polishing wheel or belt. POLISHING
WHEEL:
A wheel which can be made of
several different kinds of material, which has been coated with abrasive grain
and glue. PORTABLE
GRINDER:
One that is used manually and can be easily transported. POUNCING
PAPER: An
abrasive paper used in the Felt Industry. PRECISION
WORK: Work
which is required to be exact in measurements, finish, etc. Work that must be
ground with great care. PRODUCTION:
The quantity of product turned out or the amount of work done in a given time or
during the life of the grinding wheel. PROFILOMETER:
An
instrument for measuring the degree of surface roughness in micro inches. PROTECTION
FLANGES:
See Safety Flange. PROTECTION
HOODS:
See Hoods. RECESSED
WHEELS: Grinding
wheels made with a depression in one side or both sides to fit special types of
flanges or sleeves provided with certain grinding machines. RESINOID
BOND: A
bonding material described commercially as synthetic resin. REST:
That part of a grinding wheel stand which is used to support the work, dresser
or truing tool when applied to the grinding wheel. ROCKWELL
HARDNESS TESTER: A
machine used for testing the indentation hardness of all metals. ROLL
GRINDING MACHINE:
A machine for grinding cylindrical rolls used for rolling metal, paper, or
rubber. ROUGH
GRINDING: The first grinding
operation for reducing stock rapidly without regard to the finish the wheel
leaves. R.P.M.:
Revolutions Per Minute. RUBBER
BOND:
A bonding material, the principal constituent of which is natural rubber or
synthetic rubber. RUBBER
WHEELS:
Wheels made with a rubber bond. SAFETY
DEVICES: Devices
for the protection of operators and machines in case of accident. SAFETY
FLANGES:
Special type of flanges designed to hold together the broker parts of a wheel in
case of breakage, thus protecting the operator. SAUCER
WHEEL:
A shallow, saucer-like wheel. SAW
GUMMER: A
grinding wheel used for gumming saws. SAW
GUMMING:
Saw sharpening and sharpening with a grinding wheel. SELEROSCOPE:
An
instrument for determining the relative hardness of materials by a drop and
rebound method. SCRATCHES:
Marks
left on a ground surface caused by a dirty coolant or a grinding wheel unsuited
for the operation. SCYTHE
STONE:
A long, narrow stone for sharpening or whetting scythes by hand. SEGMENTS:
Bonded
abrasive sections of various shapes to be assembled to form a continuous or
intermittent grinding surface S.F.P.M.:
Surface
Feet Per Minute. See Peripheral Speed. SHARPENING
STONE: A
natural or manufactured abrasive stone usually of oblong shape, used for
sharpening or whetting tools. SHELLAC
BOND: A
bonding material, the principal constituent of which is shellac. SILICA:
Silicon
Oxide. SILICATE
BOND: Type
of bond matured by baking, in which silicate of soda is an important bonding
constituent. SILICON
CARBIDE:
An abrasive made from coke and silica sand. SNAGGING:
Grinding
the gates, fins and spruces from castings. SPINDLE:
See Arbor. STEADY-REST:
A
support for pieces being ground on a cylindrical grinding machine. STRAIGHT
WHEEL:
A grinding wheel of any dimension which has straight sides, a straight face, and
a straight or tapered arbor hole, and is not recessed, grooved, dovetailed,
beveled or otherwise changed from a plain straight wheel. STRUCTURE:
A general term referring to the proportion and arrangement of abrasive and bond
in an abrasive product. STRUCTURE
NUMBER: A
term designating the relative grain spacing in an abrasive product. Dense
relative spacing corresponds to low numbers such as 0, 1, 2, etc. open spacing
the higher numbers 10. 11, 12. STUB:
That
portion of a grinding wheel left after having worn down to the discarding
diameter for a particular operation or machine. SURFACE
GRINDING:
Grind a plane surface. SURFACE
GRINDING MACHINE: A
machine for grinding plane surfaces. SWING
FRAME GRINDER:
A grinding machine suspended by a chain at the center point
so that it may be turned and swung in any direction for grinding of
billet, large castings, or other heavy work, TABLE:
That
part of the grinding machine which directly or indirectly supports the work
being ground. TABLE
TRAVERSE: Reciprocating
movement of the table of a grinding machine. TAPERED
WHEEL: A
grinding wheel shaped similar to a straight wheel but having a taper from the
hub of the wheel to the face and thus being thicker at the hub than at the face.
TEMPER:
The
heat treatment of a material to develop required qualities. TENSILE
STRENGTH: The
strength of a material when tested in tension usually given in pounds per square
inch. TREATMENT:
A
material impregnating an abrasive product aiming to improve its grinding action,
often by reducing the tendency for loading in use. TRUING:
A grinding wheel is trued in order to restore its cutting face to running true,
so that it will produce perfectly round (or flat) and smooth work, or to alter
the cutting face for grinding special contours. TUMBLING:
An
operation for deburring, breaking sharp edges, finishing and polishing in which
abrasive, water and the work are "tumbled" in a rotating barrel or by
other means. UNIVERSAL
GRINDING MACHINE: A
machine on which cylindrical, internal and surface grinding can be done, usually
used for tool room work. VITRIFIED
BOND: A
bonding material which the chief constituent is clay. WASHITA
OILSTONES: A
natural stone preferred by many to produce smooth, long-lasting edges. WHEEL
SLEEVES: A
form of flange used on precision grinding machines where the wheel hole is
larger than the machine arbor. Usually, the sleeve is so designed that the wheel
and sleeve are assembled as one unit. WHEEL
SPEED: The
speed at which a grinding wheels revolving, measured either in revolutions or in
surface feet per minute. WORK:
Used
to designate the material being ground in a machine. WORK
SPEED: In
cylindrical, centerless and internal grinding, the rate at which the work
revolves, measured in either r.p.m. or s.f.p.m.; in surface grinding, the rate
of table traverse measured in feet per minute. |
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Copyright © 2002 QUICK FACT GUIDES FOR MACHINISTS
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