Grinding Wheel Materials 331

abrasive depth

The depth of the abrasive coating on the grinding wheel. Abrasive depth is a designation unique to superabrasive metal-bonded or electroplated grinding wheels.

abrasive grains

A small, hard particle that forms chips during grinding. Abrasive grains are held together by bond material to create grinding wheels and other abrasive tools.

alumina

A chemical compound of aluminum and oxygen in the form of a white powder or clear crystals. Alumina, also known as aluminum oxide, is a conventional abrasive commonly used to grind plain or alloyed steel.

aluminum oxide

A chemical compound of aluminum and oxygen in the form of a white powder or clear crystals. Aluminum oxide, also known as alumina, is a conventional abrasive commonly used to grind plain or alloyed steel.

American National Standards Institute

ANSI. A private, nonprofit organization that administers and coordinates voluntary standards and systems for products, services, and systems in the United States. American National Standards Institute designations on grinding wheels indicate grain size, material type, and other identifying information for the wheel.

ANSI

American National Standards Institute. A private, nonprofit organization that administers and coordinates voluntary standards and systems for products, services, and systems in the United States. ANSI designations on grinding wheels indicate wheel hardness, grain size, and other identifying information.

arcs of contact

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

bauxite ore

An aluminum ore from which aluminum is extracted. Bauxite ore is treated in an electric arc furnace and mixed with iron and coke to form aluminum oxide.

bond material

The adhesive material in a grinding wheel that holds the abrasive grains together. Bond materials include glass, clay, metal, rubber, and other materials.

bond material

The adhesive substance in a grinding wheel that holds the abrasive grains together. Bond material helps determine the grinding wheel's hardness.

bond post

A structural beam of bond material that connects abrasive grains in a grinding wheel. Bond post size and structure help to determine a grinding wheel's hardness.

bond type

The raw material that holds the abrasive grains together in a grinding wheel. Bond types include vitrified, organic, metal, and electroplated.

bronze alloys

An alloy consisting mostly of copper, with 10-12% tin. Bronze alloys are commonly used for metal bonds.

camshafts

A long cylindrical rod with a number of rotating or sliding lobes along its length. Camshafts can be ground using organic-bonded wheels.

carbon

A nonmetallic element that combines with metallic elements at high temperatures to form various carbides. Carbon combined with silica sand forms silicon carbide.

carbon compounds

A chemical element or combination of chemical elements that contains carbon. Carbon compounds include both organic and inorganic compounds.

carbon steel

The most basic form of steel. Carbon steel contains less than 3% of elements other than iron and carbon.

cast iron

A metal consisting of iron, more than 2% carbon, and 1 to 3% silicon. Cast irons also normally contain trace amounts of other elements.

ceramic aluminum oxide

An exceptionally hard, strong, and sharp conventional abrasive made from crushed and dried alumina gel and mixed with fused aluminum oxide. Ceramic aluminum oxide grains require very high forces in order to fracture.

ceramic aluminum oxide

An exceptionally hard, strong, and sharp conventional abrasive made from crushed and dried alumina gel. Ceramic aluminum oxide grains require very high forces in order to fracture.

ceramics

A hard, brittle material that can withstand high temperatures and resist corrosion. Ceramics can be ground using diamond grinding wheels.

cermets

A composite material made from ceramic and sintered metal. Cermets have high temperature resistance and high hardness.

chemical vapor deposition

CVD. A process that uses heat and radio waves or microwaves to break a mineral-rich gas into pieces that reassemble themselves onto a semiconductive surface. Chemical vapor deposition is used to create synthetic diamonds.

chemical vapors

A gas formed by boiling or evaporating a liquid. Chemical vapors are used in the diamond manufacturing process.

chemically resistant

Able to withstand exposure to chemicals. Chemically resistant abrasives do not react with workpieces and other materials in the grinding process.

chip

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

clay

A type of naturally occurring ceramic material. Clay and ground glass are used as bond material in vitrified-bonded grinding wheels.

coarse

A large grain in an abrasive grinding wheel. Coarse grains produce a rough surface finish.

coke

The carbon-containing residue that remains after coal distillation. Coke is mixed with iron and bauxite ore in an electric arc furnace to produce aluminum oxide.

composites

A material containing a binding ingredient and filaments of solid reinforcing material. Composites can contain concrete, metal, and ceramic.

conventional abrasives

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 wheel and workpiece. Coolant, also known as grinding fluid, helps to prevent a loaded or clogged 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 is used for large amounts of material removal.

crystalline

A predictable arrangement of atoms. A crystalline structure is present in ceramic aluminum oxide grains.

cubic boron nitride

CBN. A manufactured superabrasive with hardness that is second only to diamond. Cubic boron nitride is chemically resistant but will wear quickly in the presence of water at high temperatures.

cut-off

A grinding operation that uses a thin, aggressive grinding wheel to cut or slice through material. Cut-off grinding requires a self-sharpening wheel, such as zirconia alumina in a resin bond.

cutting tools

A device made of a hard material that removes material from a workpiece. Cutting tools can be sharpened using grinding wheels.

CVD

Chemical vapor deposition. A process that uses heat and radio waves or microwaves to break a mineral-rich gas into pieces that reassemble themselves onto a semiconductive surface. CVD is used to create synthetic diamonds.

diamond

The hardest known substance. Diamond is both a naturally occurring and a manufactured superabrasive.

electric arc furnace

A heating unit that uses electric arcs between carbon electrodes to melt steel. Electric arc furnaces can help to eliminate undesirable properties in manufactured abrasives.

electrical resistance furnace

A device that converts electric current into heat. An electrical resistance furnace passes an electric current through a conductive material to release heat.

electrically charged

A device or solution that has current flowing through it. Electrically charged chemical solutions are used to create electroplated bonds for grinding wheels.

electroplated bonds

A superabrasive bond created by immersing a metal wheel in an electrically charged chemical bath containing metal particles. Electroplated wheels have a single layer of superabrasive grains.

electroplated bonds

A superabrasive bond type created by immersing a metal wheel in an electrically charged chemical bath that contains metal particles. Electroplated wheels have a single layer of abrasive material.

electroplating

A coating method that uses electricity and a conductive solution to deposit a layer of plating metal on a metal workpiece. Electroplating is used to create superabrasive grinding wheels.

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 metal containing iron as a primary ingredient. Ferrous metals include steel.

fine

A small grain in an abrasive grinding wheel. Fine grains produce tight tolerances and refined surface finishes.

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.

forces

An influence that produces a change in an object's motion or state of rest. Forces in grinding affect the behavior of the grinding wheel.

fracture

The breaking apart of an object into two or more pieces as a result of stress. Fractured grains on a grinding wheel expose new, sharp edges.

friability

The ability of an abrasive grain to fracture and self-sharpen under stress. Friability of an abrasive grain helps determine the lifespan of a grinding wheel.

grade

The hardness of the bond in an abrasive wheel. Wheel grade can be the same for wheels with different structures.

grades

The hardness of the bond in an abrasive wheel. Wheel grade can be the same for wheels with different structures.

grain size

The size of an individual abrasive grain in a grinding wheel. Grain size, also known as mesh size, helps to determine the tolerance and surface finish that the wheel can create.

graphite

A soft, black, carbon-based powder. Graphite can form when a diamond grinding wheel grinds a ferrous metal at high temperatures.

grinding fluid

A liquid used during grinding to clean, cool, and lubricate the grinding 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 wheels

A wheel made of bonded abrasives that is used to remove material from a workpiece. Grinding wheel selection depends on grinding variables, the specific grinding operation, and expected outcomes.

hard

A grinding wheel designation that indicates a high percentage of bond material present. Hard-grade wheels retain abrasive grains longer during grinding.

hardness

A material's ability to resist penetration, indentation, or scratching. Hardness in a grinding wheel indicates how tightly the bond material holds the abrasives.

heat treatment

A controlled heating and cooling process used to change the structure of a material and alter its physical and mechanical properties. Heat treatment is often used to adjust a material's hardness.

high-speed steel

HSS. A high-performance steel used to machine metals at high cutting speeds. High-speed steel stays hard at high temperatures and resists abrasion.

inert

Chemically inactive or having a limited ability to form chemical reactions. Inert materials are used in vitrified bonds.

inorganic

A compound that does not contain carbon. Inorganic bond materials include inert clay and glass mixtures.

insulators

A material with low electrical and thermal conductivity. Insulators can reduce heat or electrical transfer between materials.

iron

A naturally abundant and commonly used metal. Iron is the main ingredient in steel.

kiln

An oven or furnace used for heating or drying. A kiln is used to finish a grinding wheel after combining abrasives and bond.

linear inch

A unit of measurement that corresponds to 1/12 of a foot. A linear inch is a one-dimensional measurement while a square inch is a two-dimensional measurement.

material removal rate

The amount of material removed from a workpiece, measured in cubic inches per minute or cubic millimeters per second. Material removal rates fluctuate depending on the type of abrasive in the grinding wheel, speed settings, and other factors.

medium

A grinding wheel designation that indicates an average percentage of bond material present. Medium-grade wheels typically have vitrified or rubber bonds.

mesh size

The size of an individual abrasive grain in a grinding wheel. Mesh size, also known as grain size, helps to determine the tolerance and surface finish that the wheel can create.

metal bonds

A strong bond type used for superabrasive grinding wheels. Metal bonds typically use sintered bronze alloys.

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.

metric system

A standard system of measurements based on the meter and kilogram. The metric system is internationally recognized.

microfracture

The breaking apart of minuscule pieces of an abrasive grain on a grinding wheel. Microfractures expose new sharp edges on an abrasive grain.

micron

A metric measurement equal to 0.001 of a millimeter, or 1/25 of a thousandth of an inch (0.00004 in). Medium-sized abrasive grains measure around 65 microns.

natural

Occurring in nature. Natural organic compounds can be used in organic-bonded grinding wheels.

natural diamonds

The naturally occurring form of a carbon mineral that is the hardest known substance. Natural diamonds are superabrasives with high hardness and wear resistance.

nickel

A corrosion-resistant element that is alloyed with other metals to form a superalloy. Nickel used in metal bonds adds hardness to a grinding wheel.

nonferrous

A metal that does not contain iron. Nonferrous metals include aluminum, copper, and zinc.

organic bonds

A bond type that contains carbon compounds and is derived from a naturally occurring material. Organic bonds tend to soften when exposed to high temperatures.

organic bonds

A category of grinding wheel bond material that contains carbon compounds. Organic bonds include resinoid, rubber, and shellac materials.

polymers

A lightweight plastic material with a high strength-to-weight ratio. Polymers are either natural or synthetic.

porosity

The relative number of openings or voids in a material. The porosity of a grinding wheel facilitates effective grinding fluid application during grinding.

porous

Full of holes that allow the material to absorb liquids. Porous bond materials allow grinding fluid to flow through the grinding wheel to the arc of contact.

properties

A material's physical and mechanical characteristics. The properties of an abrasive grain help determine how the grinding wheel will perform.

reactivity

The susceptibility of a substance to undergo change when exposed to another substance. The reactivity of a grinding wheel can alter tolerance specifications.

refractory

A material that can retain strength at high temperatures due to its low thermal conductivity. Refractory materials include conventional abrasives, such as aluminum oxide and silicon carbide.

resin

A raw material that can be natural or synthetic and is used to make plastic. Synthetic resin is used in resinoid bonds for grinding wheels.

resinoid bonds

A type of bond used in grinding wheels that offers rapid stock removal and fine surface finishes. Resinoid bonds are made from synthetic plastic resins.

rigid

Resistant to bending. Rigidity is an important characteristic in bond materials used in grinding wheels.

rolls

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

roughing

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

rubber

A natural and very elastic polymer that is harvested from the sap of tropical trees. Rubber is combined with sulfur for use in grinding wheels with organic bonds.

rubber

A tough elastic material that is hardened and treated with sulfur for commercial use. Rubber is extracted from the sap of tropical trees.

rubber bonds

A type of organic bond used in grinding wheels. Rubber bonds offer a smooth grinding action and surface finish.

semiconductive

A material with electrical conductivity that is greater than an insulator but less than a conductor. Semiconductive surfaces are used in chemical vapor deposition.

shellac bonds

A type of organic bond used in grinding wheels. Shellac bonds can be used for polishing or light-duty grinding.

silica sand

A white ceramic compound that is used in refractory materials. Silica sand is also called silicon dioxide.

silicon carbide

A chemical compound made from silicon and carbon. Silicon carbide abrasive grains are harder than aluminum oxide grains, and are also friable and more roughly shaped.

sinter

To press and heat powdered materials close to their melting point to create a solid shape. Sintering ceramic aluminum oxide particles creates uniformly sized grains.

sintering

Pressing and heating powdered materials close to their melting point to create a solid shape. Sintering creates materials with uniform contents.

soft

A grinding wheel designation that indicates a low percentage of bond material present. Soft-grade grinding wheels release abrasive grains from the bond faster during grinding.

soft

A grinding wheel designation that indicates a low percentage of bond material present. Soft-grade wheels release abrasive grains quickly during grinding.

stainless steels

A very hard steel alloy that contains at least 10% chromium. Stainless steel resists corrosion and rust.

steel alloys

Steel that contains intentionally added alloying elements to modify its characteristics. Steel alloys can be ground with zirconia alumina or other tough abrasives.

strength

A material's ability to resist forces that attempt to break or deform it. The strength of a grinding wheel is partly determined by the bond material.

submicron

A measurement less than 0.001 of a millimeer, or 1/25 of a thousandth of an inch (0.00004 in). Submicron fractures are characteristic of ceramic aluminum oxide grains.

sulfur

A naturally occurring chemical element. Sulfur is combined with rubber for use in grinding wheels with organic bonds.

superabrasive

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

superabrasives

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

superalloys

A complex metal alloy that can resist heat and corrosion. Superalloys exhibit high strength at elevated temperatures.

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 finish

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

synthetic

Manufactured or otherwise made by people. Synthetic carbon compounds are used in organic-bonded grinding wheels.

synthetic diamonds

The manufactured form of a carbon mineral that is the hardest known substance. Most diamond cutting and grinding tools are made from synthetic diamonds.

tensile strength

A material's ability to resist forces that attempt to pull apart or stretch it. The tensile strength of a workpiece helps determines the necessary type of abrasive in the grinding wheel.

thermal conductors

A material that can transmit heat. The thermal conductivity of superabrasive grinding wheels extracts heat from grinding operations.

toughness

The property that describes a material's ability to absorb energy without breaking or fracturing. Toughness is the opposite of friability.

vitrified bonds

An inorganic clay or ceramic bond material characterized by strength, rigidity, and resistance to oils, water, and temperature changes. Vitrified bonds are both hard and brittle.

wear resistance

The ability of a material to resist the gradual wearing away caused by abrasion and friction. A wear-resistant abrasive grain has less friability.

wheel speeds

The peripheral speed of the grinding wheel. Wheel speed changes based on bond material, abrasive material, and wheel diameter.

zirconia alumina

A tough, large-grain conventional abrasive made from aluminum oxide and zirconium oxide. Zirconia alumina wheels are often used in cut-off grinding.

zirconium oxide

A toxic and heavy white powder. Zirconium oxide is mixed with different percentages of aluminum oxide in order to form the abrasive zirconia alumina.