Basics of the Cylindrical Grinder 232

abrasive

A material consisting of hard particles. Abrasives are used to wear down, rub away, or machine material.

arc of contact

The portion of the grinding wheel periphery that is in contact with the workpiece at any point. A smaller arc of contact generally requires a harder grinding wheel.

automatic cylindrical grinder

A cylindrical grinder equipped with some automated components, including a device to measure the workpiece while it is mounted on the machine. Automatic cylindrical grinders do not have as many automated features as CNC grinders.

axis

The imaginary line around which a part rotates. The axis of a workpiece in cylindrical grinding passes through the middle of the part.

base

The foundation of a grinding machine that supports all the other machine components. The base of a grinder is the bottom portion of the machine.

bearings

A friction-reducing device that allows machine parts to move together without excess wear or friction. Bearings used in center-type cylindrical grinding can wear over time and affect accuracy.

camshafts

A shaft used in internal combustion engines that features multiple lobes of various shapes and sizes. Camshafts are intricately shaped and can be finished on limited purpose grinders.

center

A hardened, pointed workholding device on the cylindrical grinder that holds one end of a workpiece. Centers can be used in both the headstock and tailstock.

center holes

A hole drilled into the end of a workpiece in order to fit a workholding center. Center holes are used to hold a workpiece between centers for outside-diameter grinding.

center steady rest

An accessory on the cylindrical grinder that provides support for long, slender workpieces. Center steady rests reduce vibration.

centerline

The imaginary line around which a part rotates. The centerline on the workpiece is the point of contact in plunge grinding.

center-type cylindrical grinding

A type of cylindrical grinding that mounts the workpiece between centers. Center-type cylindrical grinding may rotate the workpiece using live centers or dead centers combined with other devices.

chips

An unwanted piece of material that is removed from a workpiece in a grinding operation. Chips form when an abrasive grinding wheel grinds the workpiece.

chucking-type cylindrical grinding

A type of cylindrical grinding that uses a chuck or collet to hold and locate the workpiece in the headstock. Chucking-type cylindrical grinding rotates the workpiece directly, since chucks and collets fit into the headstock spindle.

chucks

A workholding device with three or four adjustable jaws to fit different workpiece dimensions. A chuck holds and rotates a workpiece in the headstock spindle.

clearance

An intentional amount of space left between two components as a safety precaution. Clearance between bearings in live centers can reduce accuracy.

CNC

Computer numerical control. The use of computers, programs, and motors to automatically control tool movement and carry out sequences of machining operations. CNC grinding machines require an operator for setup, but the machine movement is controlled through automatic or computerized actions.

collet

A slitted workholding device that uses tension or pressure to hold a workpiece. Collets hold and rotate a workpiece in the headstock spindle.

computer numerical control

CNC. The use of computers, programs, and motors to automatically control tool movement and carry out sequences of machining operations. Computer numerical control grinding machines require an operator for setup, but the machine movement is controlled through automatic or computerized actions.

coolant

A liquid used during grinding to clean, cool, and lubricate the wheel and workpiece. Coolant, also known as grinding fluid, helps to prevent a loaded or clogged grinding wheel.

crankshafts

A shaft that converts piston motion to rotary motion within an internal combustion engine. Crankshafts are often finished on limited purpose cylindrical grinders because of their complex shape.

crossfeed handwheel

A manual control on a cylindrical grinding machine that moves the grinding wheel into or away from the workpiece. The crossfeed handwheel is used in plunge and traverse grinding.

crossfeed slide

The machine component on which a cylindrical grinder wheelhead is mounted. The crossfeed slide allows the wheelhead to move toward and away from the workpiece during grinding.

cycle

The time during which a machine works on a single part. Cycle time can be decreased by using grinding machines with automatic capabilities.

cylindrical grinding

A common grinding process in which a cylindrical workpiece is held on one or both ends during grinding. Cylindrical grinding rotates both the workpiece and grinding wheel in order to finish a part.

cylindrical grinding machine

A machine used to grind round, tapered, or angled features on a cylindrical workpiece. Cylindrical grinding machines can be automatic or manual.

cylindricity

A three-dimensional form tolerance that describes the allowable variability in the shape and appearance of a cylinder. Cylindricity states how close a part is to being perfectly cylindrical to a defined axis.

dead

A type of center that has no moving parts. Dead centers used in cylindrical grinding require the use of a drive plate to transmit rotation to the workpiece.

dead

A type of center with no moving parts. Dead centers used in cylindrical grinding require the use of a drive plate or other device to transmit rotation to the workpiece.

dressing

Removing dull grains, swarf, and bonding material from a grinding wheel by fracturing away the wheel surface. Dressing also sharpens the wheel.

drive dog

A device that clamps onto the workpiece and transmits turning motion from the headstock spindle, allowing work to be mounted between centers. Drive dogs are used in conjunction with drive plates in center-type cylindrical grinding.

drive motor

The device connected to a spindle on a cylindrical grinder that provides power to rotate the grinding wheel. The power of the drive motor in the wheelhead spindle exceeds the amount of all other power sources in a cylindrical grinder.

drive plate

A device that attaches to the headstock spindle and helps to rotate the workpiece. Drive plates are used in combination with drive dogs in dead centers.

driving-type

A type of center that uses bearings or friction to allow the point of the center to rotate with the workpiece. Driving-type centers are also called live centers and must be used with drive dogs.

finishing

A grinding process that achieves the required size and surface finish of the part. Finishing operations often require faster speeds and a lighter depth of cut.

gage head

A component of an automatic cylindrical grinder that measures the workpiece while it is still mounted on the grinder. Gage heads can measure the inside or outside diameter of a workpiece.

glaze

The unwanted formation of a smooth surface on a grinding wheel. Glaze can occur when the heat from grinding reacts with a loaded wheel, or when grinding is not well lubricated and the grains wear down.

grain

A small, hard particle or crystal of abrasive material. Abrasive grains are bonded together to create grinding wheels and other abrasive tools.

grinding

Using an abrasive tool to wear away a workpiece surface and achieve highly accurate measurements. Grinding operations include cylindrical grinding, surface grinding, and centerless grinding.

grinding fluid

A liquid used during grinding to clean, cool, and lubricate the wheel and workpiece. Grinding fluid, also known as coolant, helps to prevent a loaded or clogged grinding wheel.

grinding variables

The measureable rates of movement of grinding tools and workpieces. Grinding variables include speed, feed, and depth of cut.

grinding wheel

A wheel made of abrasives bonded together that is used to grind a workpiece. Grinding wheels are mounted on the wheelhead spindle.

handwheels

A machine control that an operator turns to direct the motions and operations of another machine component. Handwheels can control table movement and wheel feed on a manual cylindrical grinder.

hardware

The physical equipment used in a computer system. Hardware in a CNC machine includes the power supply, programming device, and input/output section.

headstock

The component on a cylindrical grinder that contains a spindle and a drive motor that rotates the workpiece. The headstock has a 90° range of motion.

horizontal

Positioned side to side instead of up and down. Wheel movement in plunge grinding is horizontal towards the workpiece axis.

hydraulic

Powered by the motion and pressure of liquids. Hydraulic power can be used to control the movement of gage heads on automatic cylindrical grinders.

ID

Inside diameter. The interior surface of a spherical or cylindrical object. ID grinding can be performed on a cylindrical grinder by using a special attachment on the wheelhead spindle.

ID grinding wheels

Inside-diameter grinding wheels. Wheels used for grinding the inside diameter of a workpiece. ID grinding wheels are smaller than OD grinding wheels and can have many different shapes.

ID wheel

Inside-diameter wheel. A smaller grinding wheel used for inside-diameter grinding. ID wheels can be shaped differently from wheels used for outside-diameter grinding.

infeed

How far the grinding wheel moves into the workpiece. Infeed can be controlled by using the crossfeed handwheel.

infeed

The feed of the grinding wheel into the workpiece. Infeeds in plunge grinding are measured in inches per minute and traverse grinding infeeds are measured in inches per pass.

inside diameter

ID. The interior surface of a spherical or cylindrical object. Inside-diameter grinding can be performed on a cylindrical grinding machine by using a special attachment on the wheelhead.

inside-diameter grinding

ID grinding. Grinding the interior surface of a cylindrical workpiece. Inside-diameter grinding requires a chuck or collet to hold the workpiece.

jaws

A holding device on a chuck that clamps down on a workpiece. Jaws can be fixed or adjustable.

limited-purpose cylindrical grinder

A plain, center-type cylindrical grinder that is designed or has been altered to grind a specific type of part. Limited-purpose cylindrical grinders include roll, camshaft, and crankshaft grinders.

live

A type of center that uses bearings or friction to allow the point of the center to rotate with the workpiece. Live centers are also called driving-type centers and must be used with drive dogs.

loading

A build-up of swarf on a grinding wheel that clogs the spaces between abrasive grains. Loading can be prevented by dressing and truing.

manual

Controlled by the actions of a machine operator, rather than by automated or computerized actions. Manual cylindrical grinders require a skilled operator.

meters per second

m/s. A measurement of speed that specifies the number of meters that a location on a rotating component travels in one second. Meters per second is a direct function of the workpiece or tool diameter and its rate of rotation.

OD

Outside diameter. The exterior surface of a spherical or cylindrical object. OD cylindrical grinding is more common than inside-diameter cylindrical grinding and uses larger wheels.

outside diameter

OD. The exterior surface of a spherical or cylindrical object. Outside-diameter cylindrical grinding is more common than inside-diameter cylindrical grinding and uses larger wheels.

outside-diameter grinding

OD grinding. Grinding the external surface of a cylindrical workpiece. Outside-diameter grinding methods include plunge and traverse.

part program

A series of alphanumerical instructions used by a CNC machine to perform the necessary sequence of operations to machine a specific workpiece. A part program is uploaded to a CNC machine.

peripheral speed

The distance that a given point on the perimeter of a rotating circular object travels, expressed in feet per minute or meters per second. Peripheral speed is used to describe wheel speed and work speed in cylindrical grinding.

peripheral speeds

The distance that a given point on the perimeter of a rotating circular object travels, expressed in feet or meters per minute. Peripheral speed is used to describe wheel speed in cylindrical grinding.

periphery

The perimeter of an object. The periphery of a grinding wheel contacts the workpiece in cylindrical grinding.

perpendicular

An intersection of two lines or objects at right angles. In cylindrical grinding, the grinding wheel is perpendicular to the axis of the workpiece.

plain cylindrical grinder

A basic type of cylindrical grinder that can perform a limited number of grinding operations, including center-type cylindrical grinding and tapering. Plain cylindrical grinders can have live or dead centers.

plane

A flat surface that extends infinitely in any direction in three dimensions. A plane is perfectly flat. A plane is represented by a closed four-sided figure.

plunge grinding

A type of cylindrical grinding in which the grinding wheel is fed horizontally into the workpiece, toward its axis. Plunge grinding uses a continuous infeed.

profiled surfaces

A curved or irregular surface created on a part. Profiled surfaces on a cylindrical workpiece can be ground using plunge grinding techniques.

programmable logic controller

PLC. A processor-driven device that uses computer software to provide electrical control to machines. A programmable logic controller delivers part program information to a CNC grinder.

recessed wheels

An abrasive wheel with a depressed area surrounding the wheel center on one or both sides. Recessed wheels grind using the periphery.

reciprocates

Moves side to side, or left and right. Reciprocating movement is characteristic of the sliding table on a cylindrical grinder.

relieved wheels

An abrasive wheel that gets narrower toward its center where it angles inward. Relieved wheels may also be recessed wheels.

revolutions per minute

rpm. The number of revolutions that a spindle or cutting tool completes in one minute. Revolutions per minute is a measurement of speed.

roll grinder

A cylindrical grinder designed to machine very large metal rolls. Roll grinders are a type of limited purpose cylindrical grinder.

rolls

A long, cylindrical, and often very large metal part. Rolls are used to make paper, sheet metal, and other similar products.

setup

The series of tasks necessary to prepare for processing a workpiece. Setup includes preparing machines, adjusting workholding devices or tooling, and safeguarding machine elements to ensure proper and safe operation.

sliding table

The reciprocating portion of the table on a cylindrical grinder. The sliding table is the lower of the two table portions on a cylindrical grinder.

software

A set of digitized programs and operating procedures. Software determines the actions or performance of a computer or machine.

spindle

A rotating component on a machine. Spindles on a cylindrical grinder headstock and wheelhead provide rotation for machine components.

spindle speed

The rate at which the spindle rotates. Spindle speed on a cylindrical grinder is measured in revolutions per minute and also determines wheel speed.

straight wheels

A common abrasive wheel used in grinding and cutoff operations. Straight wheels generally appear as flat disks.

surface feet per minute

sfm. A measurement of speed that specifies the number of feet that a location on a rotating component travels in one minute. Surface feet per minute is a direct function of the workpiece or tool diameter and its rate of rotation.

surface finishes

The texture of a part after it has gone through the grinding process. Surface finish is key to the performance of a finished part.

swarf

The gritty combination of chips, abrasive grains, and worn bonding material produced during grinding. Swarf can clog a grinding wheel and cause it to function improperly.

table

The part of the grinding machine that directly or indirectly supports the workpiece. On a cylindrical grinder, the table is often divided into two sections.

table reverse dogs

A control on a cylindrical grinding machine that controls the length of the table traverse. Table reverse dogs can be set manually.

table reverse lever

A control on a cylindrical grinder that stops table movement when the table is between the right and left table reverse dogs. The table reverse lever is a manual control.

table traverse handwheel

A manual control on a cylindrical grinder that moves the sliding table from side to side. The table traverse handwheel is used during traverse grinding.

table traverse rate knob

An automatic control on a cylindrical grinder that sets the speed of the sliding table. The table traverse rate knob is used during traverse grinding.

tailstock

A component on a cylindrical grinder located opposite the headstock that supports the far end of the workpiece. The tailstock can move toward and away from the headstock to accommodate different workpiece dimensions.

tapering

Grinding a workpiece to form a shape with a gradually decreasing diameter, similar to the shape of a cone. Tapering operations can be performed on a plain cylindrical grinder by adjusting the upper table.

tolerances

The allowable deviation from a given dimension that will still allow the part to perform its desired function. Tolerances indicate the allowable difference between a physical feature and its intended design.

traverse

One full side-to-side pass of the sliding table on a cylindrical grinding machine. A traverse is one "trip" of the workpiece past the grinding wheel in traverse grinding operations.

traverse grinding

A type of cylindrical grinding in which the workpiece reciprocates across the periphery of the grinding wheel. Traverse grinding uses an incremental infeed.

traverse length

The linear distance that the sliding table on a grinding machine travels in relation to the workpiece during one left or right cutting pass. Traverse length can be automatically set in traverse grinding.

traverse length

The linear distance that the sliding table on a grinding machine travels in relation to the workpiece during one left or right cutting pass. Traverse length can be controlled by using the table reverse dogs.

truing

Restoring a grinding wheel to its original, intended shape. Truing is a more precise type of dressing.

turning

A machining operation that guides a single-point tool along the length of a rotating cylindrical workpiece. Turning is commonly performed on a lathe.

universal cylindrical grinder

A manual cylindrical grinder with a pivoting headstock and wheelhead. A universal cylindrical grinder can perform many outside-diameter and inside-diameter grinding operations.

upper table

The portion of the machine table that is mounted on the sliding table. The upper table can swivel to grind tapers and irregular shapes, or it can be locked securely in place.

wheel speed

The peripheral speed of the wheel. Wheel speed is measured in surface feet per minute.

wheelhead

The part of the grinding machine on which the grinding wheel is mounted. On a cylindrical grinder, the wheelhead contains the grinding wheel, spindle, and a drive motor.

work speed

The peripheral speed of the workpiece. The work speed is set slower than the wheel speed and is also measured in surface feet per minute.

workholding

A device used to support, locate, and hold a workpiece during grinding. The workholding device establishes a relationship between the grinding wheel and the workpiece.