Grinding Processes 201

Infeed centerless grinding

A centerless grinding process for cylindrical workpieces with varying diameters. Infeed centerless grinding uses an end-stop to prevent the workpiece from passing completely over the grinding wheel.

Surface grinding

A common grinding process that uses a rotating grinding wheel to cut away precise amounts of a flat workpiece surface. Surface grinding is often one part of a sequence of machining operations.

End-stop

A device that stops a workpiece from passing all the way through the regulating and grinding wheels in infeed centerless grinding. Some end-stops eject the workpiece when grinding is finished.

Work-rest blade

A device, often with an angled edge, that supports cylindrical workpieces during centerless grinding. The work-rest blade allows the workpiece to pass through the regulating wheel and grinding wheel, rather than hold it in place like centers or a chuck.

Pneumatic

A form of fluid dynamics that uses the motion and pressure of gas, usually compressed air, to create power. Pneumatic power converts the potential energy of pressurized gas into mechanical energy.

Hydraulic

A form of fluid dynamics that uses the motion and pressure of liquids to create power. Hydraulic power uses cylinders and pistons to convert the flow of liquids into mechanical energy.

Semi-automatic grinders

A grinding machine that performs a grinding cycle independently, but requires an operator to set and start the process. Semi-automatic grinders grind a workpiece automatically, but require an operator to set and remove the part.

Manual grinders

A grinding machine that requires an operator to control every part of the grinding process. Manual grinders include smaller, hand-held machines.

Horizontal-spindle surface grinders

A grinding machine with the grinding wheel mounted on a spindle parallel to the worktable. Horizontal-spindle surface grinders typically grind on the wheel's periphery.

Vertical-spindle surface grinders

A grinding machine with the grinding wheel mounted on a spindle perpendicular to the worktable. Vertical-spindle surface grinders typically use the face of the grinding wheel.

Creep-feed grinding

A grinding method in which the depth of cut is increased while the feed rate is decreased. Creep-feed grinding removes a greater amount of material in one pass than standard surface grinding operations.

Profile grinding

A grinding method that uses specifically shaped grinding wheels. Profile grinding shapes and finishes workpieces with complex shapes or diameters.

Internal centerless grinding

A grinding process in which a cylindrical workpiece is supported and rotated by two rollers and a regulating wheel with the grinding wheel inside the workpiece to shape and finish its inner sides. Internal centerless grinding creates close concentricity between the interior and exterior of a workpiece.

Internal chucking-type grinding

A grinding process in which the workpiece is held firmly by a chuck on one end with the grinding wheel inserted into the other to shape and finish its inner sides. Internal chucking-type grinding is the most common type of ID grinding.

cylindrical grinding

A grinding process used in grinding cylindrical workpieces. In cylindrical grinding both the grinding wheel and a cylindrical workpiece are rotated together.

Formed grinding wheel

A grinding wheel shaped to create specific features on a workpiece. Formed grinding wheels can be used to produce grooves on a workpiece.

Grinding fluid

A liquid used to cool and lubricate the grinding wheel and workpiece during grinding. Grinding fluids can be composed of water, oil, or synthetic compounds, depending on the needs of the process.

Magnets

A material that creates a magnetic field which attracts iron and other magnetic substances to it. Magnets are used as workholding devices in surface grinding.

Shoes

A metal block used to locate and support a workpiece in centerless grinding. Two grinding shoes take the place of a work-rest blade and regulating wheel typically found in centerless grinding.

Throughfeed grinding

A method of centerless grinding in which the regulating wheel and work guides feed the workpiece past the grinding wheel in a straight line. In throughfeed grinding, the regulating wheel moves the part completely past the grinding wheel.

Center

A pointed cylindrical component used to hold one end of a workpiece by inserting the tip into a matching hole in the workpiece. Centers are used during cylindrical grinding to mount and rotate cylindrical parts against the grinding wheel.

Cycle

A single increment of something that happens repeatedly. A cycle involves every step of grinding a part including setting the part, grinding it, and removing it from the machine.

Spindle

A spinning or rotating component of a machine tool. The spindle holds the grinding wheel and possibly the workholding device on the grinding machine.

Chuck-type cylindrical grinding

A type of cylindrical grinding in which one end of the workpiece is held and rotated in a chuck. Chucking-type cylindrical grinding is not as precise as the center-type.

center-type cylindrical grinding

A type of cylindrical grinding in which the workpiece is held and rotated by centers on each end. Center-type cylindrical grinding allows for grinding the entire length of a workpiece.

centerless grinding

A type of cylindrical grinding in which the workpiece is not supported on a spindle. Centerless grinding supports workpieces on a work-rest blade that guides them between a grinding wheel and a regulating wheel.

Outside diameter grinding

A type of grinding performed on the exterior cylindrical surface of a workpiece. Outside diameter grinding creates a concentric surface on a cylindrical workpiece.

Computer Numerical Control (CNC)

A type of programmable automation, directed by mathematical data, which uses computers to carry out various machining operations. CNC is a self-contained system that executes program instructions to guide machine tool components.

Abrasive wheel

A wheel composed of abrasive grains held together in a bond. Abrasive wheels are used in grinding operations

Collet

A workholding device composed of segments that tighten around a center hole with a fixed size. A collet allows for more precision than a chuck.

Vices

A workholding device that uses a pair of tightly clamped jaws to secure a workpiece. Vices keep workpieces from shifting out of place during grinding operations.

Chuck

A workholding device with three or four adjustable jaws that holds a workpiece as it rotates. A chuck secures the workpiece on one end.

Regulating wheel

Commonly made of plastic or rubber bond, this wheel is used to rotate the workpiece and pull it through the operation. A regulating wheel is also known as a feed wheel.

Bonded

Held together in a substance. Bonded grinding wheels can be held together by a number of materials including fused clay, resin, shellac, and rubber.

internal diameter

ID. A type of grinding is performed on the interior surface of a cylindrical workpiece. Internal diameter grinding produces precision holes in a workpiece.

OD

Outside diameter grinding. A type of grinding performed on the exterior cylindrical surface of a workpiece. OD grinding creates a concentric surface on a cylindrical workpiece.

Tolerances

The acceptable variation from a specified dimension. Tolerances represent a part's deviation from its specifications while still allowing it to perform its desired function.

Depth of cut

The amount of material removed by one pass of the cutting tool. Depth of cut also refers to how far a grinding wheel plunges into the workpiece.

Face

The broad surface of a grinding wheel. The face is used for large material removal or to finish a wide surface area.

Downfeed mechanism

The component of a grinding machine that moves the grinding wheel downward into the workpiece material. Downfeed mechanisms may be manual as well as automated.

Dimensions

The desired measurement of a part. Dimensions encompass every measurement of a part, including length, width, and height.

Diameter

The distance from one edge of a circle, through its center, to the opposite edge. Diameter measures the width of a circle.

Finishing

The final cuts taken with a grinding wheel to obtain the accuracy and surface finish desired. Finishing often requires faster work speeds.

Bores

The interior diameter of a cylinder. Bore surfaces are often accurately ground through ID grinding.

Feed

The method of advancing parts into a machine, either automatically or by hand. Different feed methods are required for various grinding processes.

Periphery

The outermost edge of an object. The periphery of a grinding wheel is used for precise cuts.

Table

The part of the grinding machine that directly or indirectly supports the workpiece. The table may rotate or reciprocate in surface grinding.

Dressing

The process by which a tool is used to sharpen a grinding wheel. Dressing works by removing a layer of dull grains from the wheel, revealing fresh, sharp grains.

Feed rate

The rate at which the grinding wheel and the workpiece move in relation to one another. The feed rate in creep-feed grinding is slower than in conventional grinding.

Grinding

The use of an abrasive to cut the surface of a workpiece and change its shape. Grinding operations commonly use abrasive grains bonded into a wheel shape.

concentric

To be circular or to share the same center. Concentric workpieces have a very even, symmetrical shape.

Rotate

To move in a circle. Typical rotating tables move in a circular motion against a grinding wheel.

Reciprocate

To repeatedly move back and forth. Typical reciprocating tables move in a side-to-side motion against a grinding wheel.

Blanchard grinding

a common name for vertical-spindle surface grinders using a rotating table and cup-shaped grinding wheel.

Automatic grinders

a grinding machine that can perform multiple grinding cycles, independent of an operator. Automatic grinders are often available with CNC