Abrasive Finishing Processes 271

abrasive belt

A type of coated abrasive that consists of a flat band formed into a closed loop. Abrasive belts are fitted around rollers that propel the abrasive material past the workpiece surface.

abrasive blasting

A finishing process that uses air to blow abrasive media at a workpiece. Abrasive blasting uses compressed air to force media through a nozzle directed at the workpiece surface.

abrasive discs

A coated abrasive tool that is flat and circular in shape. Abrasive discs are often used for polishing.

abrasive flow machining

AFM. A finishing process that extrudes abrasives through complex internal passages to smooth surfaces, remove burrs, and round edges. Abrasive flow machining, or extrude honing, forces semi-solid abrasive media into an opening in a workpiece, through its internal features, and out of another opening.

abrasive tapes

A flexible coated abrasive that consists of a flat band wound around a reel. Abrasive tapes can be used for superfinishing.

abrasives

A material made of hard, sharp particles used for removing chips of material from a workpiece surface. Abrasives are often used in finishing operations that clean, polish, or otherwise prepare the surface of a part.

adhesive

A substance used to join two or more materials together. Adhesives are often used to fix abrasives to a backing.

air compressor

A component that pressurizes air. Air compressors are used to force abrasive grains at workpiece surfaces in blasting operations.

aluminum oxide

A very hard ceramic material composed of aluminum and oxygen. Aluminum oxide is often used as an abrasive grain because it is hard and tough.

backing

The material on which coated abrasives are adhered. Backing is typically made of paper or fabric.

barrel finishing

A mass finishing process that finishes parts inside a rotating barrel of abrasive media. Barrel finishing, or tumbling, may be a dry process or a wet process that uses abrasive media mixed with a solution.

blast cabinet

A contained area in which abrasive blasting is performed. A blast cabinet protects operators from abrasive media and allows the media to be collected and reused.

bond material

The substance that holds abrasive grains together in bonded abrasives. Bond material can be made of natural or synthetic substances.

bonded abrasives

An abrasive tool made from the combination of abrasive grains and bond material. Bonded abrasives include grinding wheels and honing stones.

bore

The interior diameter of a hollow cylindrical workpiece. Bores are finished by honing and often contain sliding parts.

buffing

A finishing process that uses pads to apply abrasive compounds to a workpiece and create a smooth, lustrous surface finish. Buffing includes two steps: cutting down and coloring.

buffs

A pad made of natural or synthetic fibers. Buffs are used to apply abrasive compounds in buffing. Buffs can be made of natural or synthetic fibers.

burrs

A sharp, ragged projection on the edge or corner of a workpiece that is left behind after a cutting operation. Burrs may be removed during finishing processes.

casting

A metalworking process that involves pouring a heated liquid material into a hollow mold and allowing the material to cool until it solidifies into its final shape. Casting creates a part surface with no clear lay but can leave raised sections that must be smoothed out.

coated abrasives

An abrasive tool composed of abrasive grains that are adhered to a backing material with an adhesive. Coated abrasives include belts, discs, and flap wheels.

coating

The process of applying a protective or decorative finish to a part surface. Coatings like paint or varnish are applied to products during the part creation process.

coloring

The final step of the buffing process that brings out a shiny finish. Coloring uses a fine abrasive compound and soft buffs to produce a high-luster finish with no visible scratches.

compounds

A solid or liquid substance that contains abrasive material. Compounds are used in a variety of abrasive finishing processes.

computer numerical control

CNC. A programmable system that uses mathematical data and microcomputers to carry out various machining operations. Computer numerical control machines can automatically control abrasive machining and grinding processes.

conditioning

A process that prepares a part for a subsequent operation. Conditioning changes a part's surface characteristics to facilitate processes that refine surface finish or add paint, plating, or coating.

cubic boron nitride

CBN. An extremely hard, chemically resistant material composed of boron and nitrogen. Cubic boron nitride is the second hardest material, after diamond.

cutting down

The initial step of the buffing process that removes scratches and smooths surfaces. Cutting down uses a coarser abrasive to prepare a surface for coloring.

cylinders

A hollow bore that houses a movable piston. Cylinders convert fluid power into linear mechanical movement.

cylindricity

The quality of a cylindrical workpiece characterized by its entire length having the same diameter relative to a common axis. Cylindricity describes how close a part is to being perfectly cylindrical.

deburring

Removing sharp projections left on a workpiece after a machining operation. Deburring ensures that a workpiece has smooth, flat edges.

diamond

A naturally occurring or manufactured stone made of crystalline carbon that is used as an abrasive. Diamond is the hardest known material.

extrude honing

A finishing process that extrudes abrasives through complex internal passages to smooth surfaces, remove burrs, and round edges. Extrude honing, or abrasive flow machining (AFM), forces semi-solid abrasive media into an opening in a workpiece, through its internal features, and out of another opening.

extruded

Forced through an object. Abrasive media is extruded through complex passages in workpieces during abrasive flow machining (AFM).

finishing

A final process performed to achieve the required geometric, dimensional, and surface specifications of a manufactured part. Finishing includes material removal processes that can create tight tolerances and smooth surface finishes.

flap discs

A coated abrasive tool that consists of many segments of overlapping abrasive material arranged in a circular shape. Flap discs are often used in manual finishing operations like polishing.

flap wheels

A coated abrasive tool that consists of many segments of abrasive material extending from the edge of a wheel. Flap wheels are often used in manual finishing operations like polishing.

fluids

A state of matter that has the ability to flow. Fluids can be liquids, like water and oil or gases, like air.

forging

A metalworking process that involves compressing bulk metal at elevated temperatures. Forging creates very strong parts but can also leave raised sections that must be smoothed out.

friability

The ability of abrasive grains to fracture and self-sharpen under stress. Friability affects an abrasive's rate of material removal and lifespan.

gears

A round or cylindrical mechanical component with teeth that is used to transmit power. Gears are designed to mesh with one another in order to alter the speed, torque, or direction of mechanical energy.

geometry

The collective measurements, properties, and relationships of the lines and points of an object. Geometry uses the components of an object to describe its unique shape.

grade

A letter designation that describes the hardness of a material. The grade of an abrasive can be any letter from A to Z, with A being the softest and Z being the hardest.

grains

A small, hard particle of abrasive material. Grains are often bonded together or coated onto backings to create grinding wheels and other abrasive tools.

grinding

A finishing process that uses an abrasive tool to remove material from a workpiece surface and achieve highly accurate measurements. Grinding operations commonly use abrasive grains bonded into a wheel shape.

grinding wheel

A disc made of bonded abrasives used to remove material from a workpiece surface. Grinding wheels rotate to remove microscopic chips of material and can produce very fine surface finishes.

grit

A number designation that describes the size of an abrasive grain. In the U.S. system, a higher grit number indicates smaller grains, and lower grit numbers indicate larger grains.

hone

A tool used to hold honing stones. The hone rotates and oscillates inside a workpiece to move the stones against the workpiece surface.

honing

A finishing process that uses abrasive stones to grind away small amounts of workpiece material. Honing is used to correct geometry, create high-quality surface finishes, and achieve tight tolerances.

honing stones

A bonded abrasive tool that may be hand-held or mounted onto a tool called a hone. Honing stones are used to finish the inside of a cylindrical workpiece.

inside diameter

ID. The interior surface of a spherical or cylindrical object. The inside diameter of a workpiece is often finished by honing.

lap plate

A flat, solid surface that is covered with loose abrasives and rubbed against a workpiece to perform finishing operations. The lap plate holds the abrasives as the workpiece moves over them, removing material.

lapping

A finishing process that uses a lap plate and abrasive compounds to bring surfaces to the desired dimensions and surface finish. Lapping uses a fine abrasive to grind away small amounts of material from a workpiece surface, resulting in very flat surfaces.

lay

The overall direction of the pattern created by the production process. Lay is one of the main characteristics used to describe surface finish.

lubricant

A substance used to prevent friction between two surfaces in relative motion. Lubricants such as oil and grease reduce resistance, wear, and heat.

lubrication

The application of lubricants, such as grease or oil, to moving surfaces that are in contact with each other. Lubrication minimizes friction, which aids movement between mechanical components and reduces heat and wear.

lustrous

Having a shining, reflective surface. Lustrous workpieces reflect light evenly across their entire surface.

magnetic abrasive finishing

MAF. A finishing process that uses magnetism to force abrasive grains against a workpiece surface. Magnetic abrasive finishing uses a mixture of magnetic particles and abrasive grains to smooth the surfaces of workpieces.

magnetic field

The area in and around a magnet in which a magnetic force exists. Magnetic fields exhibit the powers of attraction and repulsion.

manifolds

A fluid conductor that consists of a metal block with multiple integrated channels. Manifolds are designed to conduct fluid in confined spaces.

mass finishing

A process that uses loose abrasives to finish a group of workpieces simultaneously. Mass finishing processes include tumbling and vibratory finishing.

media

Grains of abrasive material or a mixture of abrasive and non-abrasive grains used to modify surface finish in finishing operations. Media is used in many abrasive finishing processes, such as blasting, mass finishing, and abrasive flow machining (AFM).

metallurgical properties

Characteristics of metal that describe its qualities and capabilities. Metallurgical properties include a variety of physical and mechanical properties such as strength.

microfinishing

A finishing process that uses fine abrasive stones to improve surface finish on the exterior of parts of various shapes. Microfinishing, also known as superfinishing or short-stroke honing, is used to create surface finishes with a higher quality than grinding or honing.

oscillation

Back and forth movement. The oscillation of the hone within the workpiece creates the desired surface finish and cross-hatched texture.

outside diameter

OD. The exterior surface of a spherical or cylindrical object. The outside diameter of a workpiece is often finished by superfinishing.

pistons

A cylindrical component that moves up and down inside a hollow cylinder. Pistons move in response to pressure exerted by fluid systems.

plating

The process of adding a thin layer of metal to serve as a decorative or protective coating on a part. Plating is used to improve the appearance or functionality of parts.

plunge superfinishing

A method of superfinishing in which the abrasive stone is fed radially into the workpiece, towards its axis of rotation. Plunge superfinishing is used for irregularly shaped workpieces.

polishing

A finishing process that uses a coated abrasive attached to a machine to remove surface material and smooth out rough sections of a part's surface. Polishing creates a visible scratch pattern on the part surface.

pressure

A physical force exerted on an object. Pressure is typically expressed in pounds per square inch (psi) or pascals (Pa).

rotation

Circulate movement. The rotation of the hone is the primary method of material removal in honing.

roughness

Fine, closely spaced irregularities remaining on a part surface after manufacturing. Roughness is created by the production process.

semiconductor wafers

A thin, round slice of semiconductive material, such as silicon, that is embedded with electrical circuitry. Semiconductor wafers must be perfectly flat and are often made by lapping.

serviceability

The condition of a workpiece surface. Serviceability describes texture, cracks, corrosion, and other characteristics.

short-stroke honing

A finishing process that uses fine abrasive stones to improve surface finish on the exterior of parts of various shapes. Short-stroke honing, also known as superfinishing or microfinishing, is used to create surface finishes with a higher quality than grinding or honing.

silicon carbide

A hard, brittle material composed of silicon and carbon. Silicon carbide is often used as an abrasive grain because it is hard and sharp.

slurry

A thick mixture of liquid and suspended solids. A slurry of abrasive grains and liquid is used in abrasive finishing processes such as lapping.

specifications

A description of the essential physical and technical properties of a finished part. Specifications outline important information, including finished part dimensions and requirements.

superfinishing

A finishing process that uses fine abrasive stones to improve surface finish on the exterior of parts of various shapes. Superfinishing, also known as short-stroke honing or microfinishing, is used to create surface finishes with a higher quality than grinding or honing.

surface finish

The degree of roughness and variation on the surface of a part after it has been manufactured. Surface finish is often described by the lay, roughness, and waviness remaining on a part.

surface grinding

A common grinding process that involves feeding the surface of a workpiece toward a rotating grinding wheel. Precision surface grinding is the most common grinding operation used for finishing.

surface integrity

The overall state of the exterior of a workpiece after it has been machined. Surface integrity encompasses many attributes, including surface finish, metallurgy, and serviceability.

through-feed superfinishing

A method of superfinishing in which rollers feed a workpiece along abrasive stones in a straight line. Through-feed superfinishing is used for cylindrical workpieces.

tolerances

The acceptable variation from a specified dimension. Tolerances indicate the allowable difference between a physical feature and its intended design.

tumbler

A barrel used to hold workpieces and abrasive media for mass finishing operations. The tumbler rotates to force the abrasives against the workpieces and remove material.

tumbling

A mass finishing process that finishes parts inside a rotating barrel of abrasive media. Tumbling, or barrel finishing, may be a dry process or a wet process that uses abrasive media mixed with a solution.

vibratory finishing

A mass finishing process that finishes parts by rotating them inside a vibrating, rotating tub of abrasive media. Vibratory finishing can be a wet or dry process.

waviness

Large, widely spaced irregularities remaining on a part surface after manufacturing. Waviness is the result of machine deflections and vibration.

welds

A mixture of fused metal that forms a joint between separate components. Welds consist of many layers of metal and are often raised above the surface of the components.