Introduction to Abrasives 101

abrasive blasting

A deburring process that removes workpiece material by using air to blow sand or other grit at the surface of a workpiece. Abrasive blasting improves the finish of a surface.

abrasives

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

acid

A corrosive chemical compound. Acid can damage materials and living tissue on contact.

adhesive

A nonmetallic chemical substance used to bond two or more materials. An adhesive is used to hold abrasives grains to the backing in coated abrasives.

aluminum

A lightweight metal that is silvery white in color. Aluminum resists corrosion and is a good conductor of electrical and thermal energy.

aluminum oxide

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

American National Standards Institute

ANSI. A private, nonprofit organization that administers and coordinates voluntary standards and systems in the United States. The American National Standards Institute produces standards for abrasive grit sizes.

attrition

The wearing down and dulling of abrasive particles due to friction. Attrition is reduced by an abrasive's ability to self-sharpen.

backing

The material on which coated abrasive grains are adhered to create a coated abrasive tool. Backing is made of fabric, paper, or other similar material.

blasting

A group of finishing processes that involve spraying a surface with various types of media at high velocities in order to remove contaminants. Blasting media is most frequently different types of abrasive grains, but high-pressure streams of air or water can also be used.

bond material

A material that holds abrasive grains together in an abrasive tool. Bond material may consist of rubber, metal, or other material.

bonded abrasives

An abrasive tool made from the combination of abrasive grains and bond material. Bonded abrasives are typically in the form of grinding wheels but also include other surface grinding products.

brittle

Hard and more likely to break instead of bend when subjected to force or pressure. Brittle abrasive grains typically fracture, exposing new, sharp edges and preventing dulling.

bronze alloys

A metal material consisting mostly of copper and 10-12% tin. Bronze alloys are commonly used for metal bonds.

burrs

A sharp projection on a workpiece surface that is left by a cutting tool after a cutting operation. Burrs must be removed to ensure precise grinding.

carbon

C. A common, strong, nonmetallic element. Carbon is found in steel, carbide, diamond, and other materials.

carcinogenic

Having the potential to cause cancer. When used in abrasive blasting processes, sand produces toxic, carcinogenic dust that is hazardous if inhaled.

CBN

Cubic boron nitride. A synthetic material composed of boron and nitrogen. CBN is the second-hardest known substance, after diamond, and is used as an abrasive grain.

ceramic

A hard, brittle material that can withstand high temperatures and resist corrosion. Ceramics include traditional materials, such as brick and clay, as well as advanced ceramics used as abrasives, cutting tools, and electrical components.

chemically react

To undergo a change due to contact with another substance. Natural and synthetic diamond chemically react with iron at high temperatures, changing their physical structure and causing them to break down.

chips

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

closed coat

A dense arrangement of abrasive grains in coated abrasives. Closed-coat abrasives have little space between each grain.

coated abrasives

An abrasive tool composed of abrasive grains adhered to a flexible backing material, such as paper, plastic, or cloth. Coated abrasive tools are often used for finishing operations.

conical

Having a three-dimensional (3D) cone shape with a cylindrical base, tapered sides, and a pointed tip. Conical grinding wheels are used for workpiece interiors.

cubic boron nitride

CBN. A synthetic material composed of boron and nitrogen. Cubic boron nitride is the second-hardest known substance, after diamond, and is used as an abrasive grain.

cylindrical

Having a three-dimensional (3D) shape consisting of a circular base and top connected by parallel walls. Cylindrical grinding wheels are used for workpiece interiors.

deburring

A finishing process that uses an abrasive to remove sharp projections left by a tool on a workpiece surface. Deburring is often done by hand or in mass finishing processes.

dense structure

A bonded abrasive tool structure with little distance between its abrasive grains. Bonded abrasive tools with dense structures are best for hard materials.

diamond

A naturally occurring or synthetically made mineral that is the hardest known substance. Diamond is often used in manufacturing for cutting and grinding hard materials.

Federation of European Producers of Abrasives

FEPA. An association of European manufacturers of abrasive products with strong links to manufacturers in the United States. The Federation of European Producers of Abrasives provides safety recommendations and product standards related to abrasives.

ferrous

A material in which iron is the main ingredient. The most common ferrous metals are steel and cast iron.

finishing

A group of processes that are performed to obtain the proper tolerance and surface finish for a completed part. Finishing processes, such as grinding, lapping, and honing, use abrasives to remove very small amounts of workpiece material.

flap wheels

A coated abrasive tool consisting of many segments of abrasive sheets extending from the edge of a wheel. Flap wheels are often used in hand-held grinding operations.

fracture

The breaking apart of an object into two or more pieces as a result of stress. Abrasive grains fracture during a process, exposing new, sharp edges.

friability

An abrasive grain's ability to fracture and self-sharpen under stress. Friability helps abrasives cut more easily and prevents them from dulling.

garnet

A naturally occurring mineral that is usually pink or reddish in color. Garnet is sometimes used as an abrasive grain in polishing.

grade

A letter designation that describes the hardness of a material. Grade A abrasives are the softest and Grade Z are the hardest.

grains

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

grinding

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

grinding wheels

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

grit

A number designation that indicates the size of an abrasive grain. ANSI uses higher grit numbers to indicate smaller grains, while FEPA uses higher grit numbers to indicate larger grains.

hardness

The ability of a material to resist penetration and scratching. Hardness is one of the key properties of abrasive grains.

honing

A finishing process that uses an abrasive to create high-quality surface finishes and tolerances. Honing operations commonly use abrasive stones to grind away small amounts of workpiece material.

honing stones

A bonded abrasive tool used for finishing that may be hand-held or mounted. Honing stones are used to finish the interior of round holes as well as flat surfaces.

impact resistance

A material's ability to withstand sudden shock or impact without deforming or breaking. Impact resistance is higher in metal bonded abrasive tools than abrasive tools with vitrified or organic bonds.

iron

A malleable, silver-gray metal that is highly magnetic. Iron is alloyed with carbon to make steel.

kiln

A furnace used for heating or drying. Kilns are used to finish a grinding wheel after combining abrasive grains and vitrified bonds.

lapping

A finishing process that uses an abrasive to remove the last bit of unwanted material and bring a surface to a desired state of finish or tolerance. Lapping uses a fine abrasive to grind away small amounts of material from a workpiece surface.

machining

A manufacturing process that involves removing material to form an object. Machining can occur using traditional methods, like turning, drilling, milling, and grinding, or with less traditional methods that use electricity, heat, or chemical reaction.

make coat

A layer of adhesive between the backing material and the abrasive grains on a coated abrasive. The make coat is the first layer of adhesive that helps the abrasive grains stick to the backing.

mandrel

The rotating shaft on which honing stones or other abrasives are mounted. A mandrel is used in honing as a workholding device.

mass finishing

A deburring process that uses loose abrasive grains to remove sharp projections from a workpiece surface. Mass finishing can simultaneously improve the surface finish of a group of workpieces.

metal

A hard, strong material that conducts electricity and heat. Metals include copper, steel, iron, nickel, and lead.

metal bonds

A type of organic bond material that is made from cast iron and bronze alloys. Metal bonds result in abrasive tools with long performance lives.

metal cutting

A group of machining processes that use a cutting tool to remove metal from a workpiece in the form of chips. Metal cutting operations include milling, drilling, and turning.

natural abrasives

A hard material found in the earth. Natural abrasives, like sand and diamond, are used to shape other materials through a grinding action.

nonferrous

A material that does not contain iron or consists mostly of elements other than iron. Aluminum, copper, and zinc are nonferrous metals.

open coat

A sparse arrangement of abrasive grains in coated abrasives. Open-coat abrasives have more space between each grain.

open structure

A bonded abrasive tool structure with greater distance between its abrasive grains. Bonded abrasive tools with open structures are best for soft materials.

organic bonds

A category of bond material that contains carbon compounds and has the tendency to soften when exposed to heat. Organic bonds include resinoid, rubber, and shellac materials.

periphery

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

polycrystalline diamond

PCD. The synthetic form of diamond that has a hardness approaching natural diamond. Polycrystalline diamond is used as ultra-hard abrasive grains.

porous

A material that has holes or openings through which air or liquid can pass. Porous abrasives may improve grinding efficiency due to increased friability.

properties

A material's distinguishing physical and mechanical characteristics. The properties of an abrasive grain, such as hardness and toughness, affect the performance of an abrasive tool.

rigid

Resistant to bending. Rigid materials are stiff and inflexible and are useful in applications that require a part to hold its shape.

sand

A substance consisting of loose, small grains of rock. Sand is not commonly used in blasting as it requires expensive safety equipment.

shank

The stalk or post on which a grinding tool is mounted. A shank provides support for the tool.

silicon carbide

A hard and brittle synthetic material composed of silicon and carbon. Silicon carbide is often used as an abrasive grain when grinding aluminum.

single-point cutting tool

A tool that uses one cutting edge at a time to remove workpiece material. Abrasive grains act as individual single-point cutting tools during abrasive manufacturing processes.

size coat

A layer of adhesive covering the abrasive grains on a coated abrasive tool. The size coat is the final layer of adhesive that secures the grains in place.

specifications

A description of the essential physical and technical properties of a finished part. Specifications outline important information including finished part dimensions and how the part must respond to processes.

spindle

A rotating component of a machine tool that can hold and rotate tools. Grinding wheels and other cutting tools are usually mounted on a spindle.

steels

A ferrous metal consisting of iron and carbon, usually with small amounts of manganese, phosphorus, sulfur, and silicon. Steels are the most common metals used in manufacturing.

strength

A material's ability to resist forces that attempt to break or deform it. Strength is an important mechanical property.

structure

The relative arrangement of grains and other materials in an abrasive tool. Structure helps determine the amount of grains and space between them.

superalloys

A complex metal with a number of additives that has excellent strength and resistance to deformation, heat, and corrosion. Superalloys are very expensive and difficult to machine.

surface finish

The degree of smoothness on a part's surface after it has been machined or otherwise shaped. Surface finish can be improved through final machining processes that use abrasives.

swarf

A combination of finely ground chips of workpiece material and abrasive particles that are cast off during an abrasive finishing process. Swarf can appear as powder or chips depending on the workpiece, abrasive material, and process.

synthetic abrasives

A man-made hard material that is manufactured through chemical and/or physical processes. Synthetic abrasives, such as aluminum oxide and silicon carbide, are extremely hard and often used to shape other materials through a grinding action.

tolerance

An unwanted but acceptable deviation from a given dimension. Tolerances indicate the allowable difference between a physical feature and its intended design.

tough

Able to absorb energy or sudden stress without breaking. Tough abrasive grains are less likely to fracture and more likely to dull.

vitrified bonds

A clay or ceramic bond material characterized by its strength, rigidity, and resistance to oils, water, and temperature changes. Vitrified bonds have qualities similar to glass.

wear resistance

A material's ability to resist the gradual wearing away caused by abrasion and friction. Increased wear resistance can lengthen the life of a material.