Cylindrical Grinder Operation 252

abrasive grain

A small, hard particle that is used to grind a workpiece. Abrasive grains are combined with bond material to form a grinding wheel.

angle-approach grinding

A type of plunge grinding that allows the face and diameter of a workpiece shoulder to be ground simultaneously. Angle-approach grinding uses an angle-dressed wheel.

angle-dressed

A grinding wheel that has been dressed to create a specific angle or profile. An angle-dressed wheel is used in angle-approach grinding to grind a workpiece shoulder.

axis

The imaginary line around which a part rotates. A common axis of rotation exists between the grinding wheel and the workpiece in cylindrical grinding.

base

The foundation of a grinding machine that supports all 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 in live centers can wear over time and reduce accuracy.

bore

The interior diameter of a hollow cylindrical workpiece. Bores are finished or enlarged by inside-diameter grinding.

bores

The interior diameter of a hollow cylindrical workpiece. Bores are finished or enlarged by inside-diameter grinding.

carbide

A common cutting tool material that is very hard and wear resistant. Carbide crush rolls are used in profile grinding.

center holes

A hole drilled into the end of a workpiece in order to fit a workholding center. Center holes cannot be drilled when grinding the inside diameter of a workpiece.

center steady rest

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

centers

A hardened, pointed, cylindrical component used to hold one of two workpiece ends during center-type cylindrical grinding. A center's tip is inserted into a matching hole on the end of a workpiece.

chatter marks

Surface imperfections on the workpiece caused by vibrations from an imbalanced grinding wheel. Chatter marks leave slight waves on the surface of a workpiece.

chips

An unwanted piece of material that is removed from a workpiece during grinding. Chips form when a grinding wheel grinds the workpiece.

chucks

A workholding device that holds a workpiece in the headstock as it rotates. A chuck has moveable jaws that adjust to fit workpiece dimensions.

clearance

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

collet

A slitted workholding device that holds a workpiece in the headstock as it rotates. A collet has a hole through which the workpiece passes and is designed to hold a range of dimensions.

complementary

An angle that adds up to 90° when combined with an adjacent angle. Complementary angles appear to be mirror images of one another.

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.

conventional abrasive

The category of abrasive materials that includes the most commonly used, inexpensive abrasives. Conventional abrasives are refractory materials.

coolant

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

crossfeed handwheel

A control on a cylindrical grinding machine that feeds the wheel into the workpiece during grinding. The crossfeed handwheel controls the infeed rate.

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.

crush roll

A hard abrasive wheel that has the desired workpiece profile ground into it. The crush roll is fed radially into the rotating grinding wheel to crush the desired form into the grinding wheel.

crush-dressing

The use of steel or carbide rolls to create a specific shape or contour on the operating face of a grinding wheel. Crush-dressing is also known as forming.

cycle

The time during which a machine works on a single part. Cycle time in cylindrical grinding includes dwell time and spark-out.

cylindrical grinding

A common grinding process in which a cylindrical workpiece is held on one or both ends during grinding. Cylindrical grinding rotates the workpiece around a fixed axis of rotation.

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.

dead centers

A type of center with no moving parts. Dead centers used in cylindrical grinding require the use of a drive plate to rotate the workpiece.

deflection

A deviation from a straight line or plane when a force is applied. Deflection is more common in long, thin workpieces reacting to the force of the grinding wheel.

dial indicator

A measuring instrument with a contact point attached to a spindle and gears. Dial indicators are used to check workpiece alignment.

diamond dresser

A tool that uses one or more diamonds to remove material from the surface of a grinding wheel. Diamond dressers are used to true and dress a grinding wheel.

dressing

Removing swarf and dull grains from the periphery of a grinding wheel by fracturing away the wheel surface. Dressing also conditions the grinding wheel so that it can achieve proper surface finish on a workpiece.

drive dog

A device that clamps onto a workpiece and transmits turning motion from the headstock, allowing a workpiece to be held between centers. Drive dogs are attached to drive plates with dead centers.

drive plate

A device used in combination with dead centers in center-type cylindrical grinding in order to rotate the workpiece. Drive plates attach to drive dogs and are mounted on the headstock.

driving-type center

A type of center that uses bearings or friction so that the center rotates with the workpiece in the headstock spindle. Driving-type centers are also called live centers.

dwell time

An intentional time delay used at the end of a plunge grinding cycle during which the rotating wheel remains in contact with the rotating workpiece but without a continuous infeed. Dwell time helps bring a part to size.

elastic deformation

The temporary change in the shape of an object as a result of force. Elastic deformation of a workpiece is not present once the force is removed.

feeds

The rate of movements of the workpiece, grinding wheels, and other machine components. Feeds in grinding often involve linear movement from one point to another and can be measured in inches per minute or millimeters per minute.

finishing

A material removal process that achieves the required size and surface finish of a part. Finishing operations emphasize smooth surface finishes.

forces

The push or pull that gives energy to an object. Forces build up during cylindrical grinding between the workpiece and the grinding wheel.

forming

The use of steel or carbide rolls to create a specific shape or contour on the operating face of a grinding wheel. Forming is also known as crush-dressing.

grinding variables

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

grinding variables

The measureable rates of movement of the grinding wheel and the workpiece. Grinding variables include speed, feed, and depth of cut.

grinding wheel

A wheel made of bonded abrasives that rotates against a workpiece to remove small chips of material. Grinding wheels grind using their periphery.

hardness

A material's ability to resist penetration, indentation, or scratching. Hardness levels in superabrasive grinding wheels are much higher than in conventional abrasive wheels.

headstock

The end of a cylindrical grinder that contains a spindle and the drive motor that rotates the workpiece. The headstock can swivel toward and away from the wheelhead.

hydraulic

Powered by the motion and pressure of liquids. The hydraulic unit of a cylindrical grinder is contained in the base.

ID grinding

Inside diameter grinding. Grinding the interior surface of a cylindrical workpiece. ID grinding uses a chuck or collet as a workholding device.

ID grinding

Inside-diameter grinding. Finishing the interior of a workpiece hole. ID grinding requires chucks or collets to hold the workpiece during grinding.

ID grinding wheel

Inside-diameter grinding wheel. A grinding wheel that is designed for grinding operations on the inside of a workpiece hole. ID grinding wheels are often the same shape as outside-diameter wheels but are much smaller.

infeed

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

inside-diameter grinding

ID grinding. Grinding the interior surface of a cylindrical workpiece. Inside-diameter grinding uses a chuck or collet as a workholding device.

jaws

Holding devices on a chuck that clamp down on a workpiece. Jaws can be fixed or adjustable.

live center

A type of center that uses bearings or friction so that the center rotates with the workpiece in the headstock. Live centers are also called driving-type centers.

loaded

A grinding wheel that has a build-up of swarf clogging the spaces between abrasive grains. A loaded wheel can be corrected by dressing.

manual

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

material removal rate

The depth of cut multiplied by the work speed multiplied by the width of cut. Material removal rate is measured in cubic inches per minute or cubic inches per second.

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 grinding wheel diameter and its rate of rotation.

OD

Outside diameter. The exterior surface of a workpiece. Outside-diameter grinding is more common than inside-diameter grinding and uses differently shaped wheels.

outside-diameter grinding

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

peripheral speed

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 and work speed in cylindrical grinding.

periphery

The perimeter of an object. Many types of grinding wheels grind with their periphery.

plunge grinding

A type of cylindrical grinding in which the grinding wheel feeds continuously and radially into the workpiece, toward its axis. Plunge grinding can be used to grind the inside or outside diameter of a workpiece.

porosity

An empty space between abrasive grains on a grinding wheel. Porosity provides clearance for swarf and allows grinding fluid to flow through the arc of cut.

profile grinding

Removing workpiece material from the outline of a part feature within a given plane. Profile grinding can create features such as tapers, angles, or steps.

rough grind

Aggressive cutting or grinding done with little regard for surface finish. Rough grinding generally has a high material removal rate.

roughing

A material removal process with a high material removal rate. Roughing processes grind a workpiece close to its finished size but without regard for surface finish.

shoulders

A 90° angled surface on a workpiece that is created on a lathe and finished on a cylindrical grinder. A shoulder can join two different diameters on a workpiece.

sliding table

The lower portion of the table on a cylindrical grinder. The sliding table reciprocates during traverse grinding.

spark-out

A set number of grinding wheel passes at the end of a traverse grinding cycle during which the rotating wheel remains in contact with the rotating workpiece but without any infeed. Spark-out helps bring a part to size.

spindle

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

spindle

A rotating component on a machine. Spindles on a cylindrical grinder headstock provide workpiece or workholding rotation.

steel

A metal consisting primarily of iron and carbon, usually with small amounts of other elements. Steel rolls are used in profile grinding.

steps

A part feature that resembles stairs, with progressively smaller diameters meeting at right angles. Steps can be created with plunge grinding.

superabrasive

A group of relatively expensive but effective materials possessing superior hardness and abrasion resistance. Superabrasive materials for grinding are cubic boron nitride and diamond.

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 grinding wheel diameter and its rate of rotation.

surface finishes

The final texture of a part. 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. The table on a cylindrical grinder is often divided into two portions.

table reverse dogs

A control on a cylindrical grinder that automatically reverses the direction of the table traverse at the end of a pass. Table reverse dogs are used in traverse grinding to set the length of a table traverse.

table reverse lever

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

table traverse

The reciprocating movement of the sliding table on a cylindrical grinder. Table traverse is set at the beginning of a traverse grinding cycle.

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

The control on a cylindrical grinder used to adjust the speed of table traverse. Table traverse rate knobs are used in 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.

taper

A gradually decreasing diameter, similar to the shape of a cone. Tapering operations require operators to swivel the machine headstock or wheelhead to grind on a steep angle.

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 grinding

A type of cylindrical grinding in which the workpiece is fed side to side across the periphery of the wheel by using the machine's reciprocating table. Traverse grinding uses an incremental infeed rather than a continuous infeed.

traverse length

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

traverse rate

The speed of the reciprocating table. Traverse rate is expressed in inches or millimeters per minute.

traverses

Moving back and forth or from side to side. Traverse motion of the sliding table is used during traverse grinding.

truing

An operation that restores the periphery of the grinding wheel so that it is concentric to the spindle center. Truing is different for conventional abrasives and superabrasives.

turning

A machining operation that guides a single-point tool along the length of a rotating cylindrical workpiece to remove material. 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 table on a cylindrical grinder that can swivel to grind tapers or irregular shapes. The upper table can be locked or secured into place.

wheel guard

A protective cover secured over a grinding wheel to protect workers from broken wheels or debris. Wheel guards are required by the Occupational Safety and Health Administration.

wheel speed

The peripheral speed of the grinding wheel. Wheel speed is faster than work speed.

wheel type

A number used to identify a specific grinding wheel shape. Wheel type is often used to specify wheel shape in grinding wheel catalogs.

wheelhead

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

work speed

The peripheral speed of the workpiece. The work speed is set in relation to the wheel speed.

workholding

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