Abrasives Dictionary

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Materials Dictionary for Abrasives

Key guide to abrasives terms:

Abrasive

Usually any material used to cut, grind or polish. In choosing the right abrasive for a particular application, key properties that are important including hardness, strength, thermal conductivity, heat capacity, chemical inertness, grain shape, grain size. The abrasive must be harder than the material being removed.

Aluminium oxide

Aluminium oxide (Al2O3) is also referred to as alumina or aloxite. It is used as a component in cutting tools because of its hardness and versatility. Other non-abrasive uses include wear parts, as a refractory materials and in the production of aluminium metal. It is a manufactured or man-made abrasive product.

Backing Materials

Materials that are used to support abrasive grains in coated abrasive productions. Typical backing materials are paper, fabric, vulcanised fibre, non-woven backings, polyester films.

Ball Mill

Machinery used to reduce particle size by breaking agglomerations of particles into individual particles. These are then graded into different sizes and shapes.

Belt Slice

The area of an abrasive belt where the two ends are joined together with an adhesive to make an endless belt.

Bond Types

Generally bonds fall into three main categories, metal, resin or vitrified(glass). When mixed with the abrasive grains, the combined material is field at high temperatures to complete the bonding of the materials and then pressed to form the required shape.

Bonded Abrasive

In general a bonded abrasive is made up of abrasive grains that are mixed with a binder such as glass, resin, rubber and formed into a useful shape such as a wheels, cylinders, cones or blocks. Bonded abrasives are used for both grinding wheels and abrasives stones or sticks. These are used to remove surface materials such as metal, ceramics, glass, plastics and paint.

Capillarity

The property related to the ability of an abrasive grain to be wetted by capillary action. Normally this is some indication of how clean the abrasive grain is.

Boron Nitride

Boron Nitride is a man-made substance which was first synthesized in 1957 and is used in grinding due to its hardness.

It is made up of Boron and Nitrogen. Carbon is situated in between Boron and Nitrogen in the periodic table. Carbon and Boron have the same number of electrons, but unlike Carbon’s electrons, which are mobile, those of Boron are bound firmly by the nitrogen in Boron Nitride.

There are two forms of Boron Nitride, Hexagonal (h-BN) and Cubic (c-BN.) Hexagonal Boron Nitride has low friction properties, is white in colour, has good thermal conductivity, is an electrical insulator and is a dry lubricant. Cubic Boron Nitride is very similar to diamond and second only to diamond in hardness.

Brown Fused Aluminium Oxide

An Alumina based abrasive with an added content of TiO2 to increase toughness. It is a very commonly used abrasive widely found in Bonded, Coated, Refractory and Industrial Markets.

Ceramics

Ceramics are a broad range of materials with use in diverse industries. Normally can be classed as an oxide, non-oxide or composite. Abrasive ceramic materials include alumina, zirconia, carbides, borides, nitrides, silicides and combinations of oxides and non-oxides. Ceramics are used for abrasion and cutting tool applications. General characteristics of ceramics include extreme hardness and chemical inertness.

Cermet

Composite of ceramic and metals which combine high temperature resistance and hardness with metal properties.

Cerium Oxide

A softer material than either alumina or silicon carbide, cerium oxide is main used for polishing glass and quartz. It is naturally occurring.

Chatter

An undesirable, repetitive pattern created on a workpiece surface due to an out-of-round or out-of-balance condition in the abrasive equipment.

Coated Abrasive

Similar to bonded abrasives, through coated abrasives usually conform to the shape of the workpiece. Normally abrasive grains are attaches to the surface of flexible or semi-flexible backings and are used in both DIY and industrial applications. Typical grains for coated abrasives are -aluminium oxide, aluminia-zirconia, cubic boron nitride, diamond, garnet and silicon carbide. Coated abrasives are used for conventional surface preparation and finishing and all types of material.

Colloid

Colloids are often used for fine polishing or as a feedstock for non-fused abrasive manufacture. In general terms colloids are a suspension of a solid in a liquid, like milk.

Crude

Refers to large pieces of abrasive which can be either after primary crushing or in an ingot form.

Crusher

As its name implies, this reduces the size of abrasive grains. Typical crusher types include jaw, gyratory, roll and hammermill.

Cubic Boron Nitride (CBN)

The second hardest material after diamond, cubic boron nitride was first synthesised in the 19xx using the same high pressure high temperature process used to produce diamond. The material shares many of the attributes and properties of diamond, particularly high thermal conductivity, excellent wear resistance and good chemical inertness and can be used for abrasive and cutting applications for steel and iron materials which is one of its main advantages over diamond. CBN is also produced in a polycrystalline form, PCBN.

Diamond

Natural and synthetic types of diamond are used as an industrial abrasive though synthetic diamond now dominates the market. Diamond is used widely used an abrasive in high productivity tools. Main areas of use for diamond grit are stone and construction, precision engineering.

Diamond is the hardest know Abrasive product that is commercially available.

Electrode discharge machining, EDM

Also known as spark machining, spark eroding, die sinking or wire erosion. Electrical discharges are used to cut or remove material. Often used in diamond processing to cut polycrystalline diamond products to final shape.

Electrocoat

Method of coating grain to a backing in which the abrasive grain is electrostatically oriented to produce maximum sharpness and even spacing between adjacent grains.

Emery

Emery is normal used in powder form. It is an odourless mineral and is mainly used in polishing applications. It is a grey-black material consisting of either aluminium oxide and either hematite or magnetitie. Use on emery boards or cloth. Emery can be sourced naturally from mines or grown under controlled conditions.

FEPA – Federation of European Producers of Abrasives

FEPA is an association of European manufacturers of abrasive products and their Trade Associations. The FEPA members include senior managers from the largest abrasive companies in the world.

These companies are produce a wide range of high quality abrasives including Bonded abrasives (vitrified and resinoid), Coated abrasives, Superabrasives (diamond and cBN).

While FEPA is predominantly a European organisation, it also has strong links with non-European Federations and abrasive manufacturers in other abrasive producing countries like India and the USA.

Projects are owned by technical commissions and sub-commissions. The main commissions are:

  • Commission I – Bonded Abrasive projects
  • Commission II – Coated Abrasive Projects
  • Commission III – Conventional Abrasive Grain projects
  • Commission V – Superabrasive and Superabrasive Grain projects
  • Commission VI – Environmental Health & Safety projects
  • Combined Commission – projects common to several Commissions

Visit the main FEPA website.

Friability

A property that describes the relative breakdown of an abrasive grain through attrition such as grinding,milling, blasting etc.

Foam Abrasives

Usually these take the form of foam sanding blocks and pads of different shapes and hardness for precision finishing of woods, fillers, paints and coatings.

Fusion

Melting of raw materials, often in an electric arc furnace, to create abrasives ingots. Most often associated with alumina type abrasive grains.

Garnet

Garnet is a mineral that has been used as a gemstone and an abrasive since the Bronze Age. Normally mined, it is widely used as an abrasive in both sand blasting and waterjet cutting applications. Fine grades of garnet are also used for glass polishing and lappling. It can also be used for cutting applications of a range of workpiece materials.

Hardness

The Mohs scale of mineral hardness provides a measure of the scratch resistance of various minerals. Diamond scores 10 on this relative scale, corundum 9 and talc only 1. Another measure is Knoop hardness.

Mesh

Normally grits or particles are graded by meshes, and this determines the distribution of different grain sizes.

Hydrated Alumina

Aluminium oxide with water chemically bonded to the alumina. The grains are soft and small in size (1mm or less.) This material is used for polishing other materials where a fine finish is desired.

Micro Abrasives

Typically these are products on special backing material such as polyester to produce defined surface structure. Used in industries such as graphics, optical and automotive industries.

Particle Size

A flat or shaped support for a coated abrasive best in the area where pressure is applied to the work piece.

Platen

A flat or shaped support for a coated abrasive best in the area where pressure is applied to the work piece.

Polycrystalline Cubic Boron Nitride, PCBN

This form of cubic boron nitride is a composite formed by sintering together selected CBN particles at very high temperatures and pressures in the presence of a metal/ceramic binder material. The result is PCBN that can be used in cutting tools. PCBN is generally used for both rough and finishing machining of grey cast iron, hard case irons and certain steels. PCBN cutting tools can be used on an ferrous work piece material that is hard or abrasives. PCBN has a combination of toughness, hardness and thermochemical stability.

Polycrystalline Diamond

This material is a synthesised, tough grown mass of diamond particles in a metal matrix. It is produced by sintering under high temperature and pressure. The sintering process is tightly controlled and an extremely hard, abrasion resistant material structure results. Polycrystalline diamond is used in mining, woodworking, metalworking and oil and gas industries.

Pumice

Pumice is the only rock that floats on water and is formed when volcanic lava has a high content of water and gas. As an abrasive product it is used as a powder for smoothing and polishing.

Shedding

A term that is used to denote the loss of abrasive grain from a product during grinding by a means other than that related to attributive wear.

Silicon Carbide (SiC)

As an abrasive silicon carbide is manly used used to grind materials that have some hard or brittle qualities, including ceramics, glass, cast iron and cemented carbides. It is man-made by a series of vapour-phase reactions in silicon dioxide and carbide at high temperatures in a furnace. The most widely used forms of silicon carbide are black and green types. While the pure form is colourless, iron impurities can result in colours. Green Silicon Carbide is the purest format 99% or more SiC and it is usually used in grinding wheels for industrial applications. Black Silicon Carbide is less pure at around 95-98% SiC and is used in Bonded, Coated, Refractory and Industrial sectors for various applications.

Slurries

Slurries, pastes and compounds are used in lapping and polishing. Usually a very fine grit such as diamond is used. These can be dry or wet.

Superabrasives

Generally diamond and cubic boron nitride are defined as superabrasives and used in applications where extreme strength and abrasiveness are required.

Tungsten Carbide

Tungsten Carbide often shortened to WC or just carbide is a class of compounds containing tungsten and carbon. It is widely used in cutting tool applications. It is made by cementing grains of tungsten carbide in a binder matrix of the metal cobalt in a process called liquid phase sintering. Tungsten carbide is four times harder than titanium and twice as hard as steel.

Unified Abrasives’Manufacturers Assocation

An organisation with global aspirations to support the promotion of safe abrasive products worldwide.

White Fused Aluminium Oxide

A form of Aluminium Oxide high in chemica purity (99% or above.) It is used in the medical and dental sectors as high purity is important. It is generally speaking softer than other abrasives. Granules are typically blocky.

White Calcined Aluminium Oxide

A form of aluminium oxide that is high in purity (99.5% or above.) It is manufactures from crystals which are grown at a high temperature. It is used in a variety of lapping, buffing and polishing applications.

Zirconia Alumina

The toughest Alumina based abrasive. A mixture of zirconium oxide and aluminium oxide, this an abrasive that is a common sand blasting medium and is used in casting and foundry processes. It is normally used as a coated abrasive for applications requiring heavy stock removal under high pressures and temperature. The material is made by a process called stress induced transformation toughening and the addition of zirconia doubles the composites strength and increases its toughness by up to four times.