As a kind of materials, abrasive grains can be distinguished in a variety of ways. They are classified as either natural or synthetic abrasives by manufacturing; either conventional or super abrasives by using history.Learn more
Natural Abrasives Specifications
Guide for Natural Abrasives Specifications
Corundum:Corundum is a natural rock-forming mineral in a trigonal crystalline form of aluminum oxide (Al2O3) mixed with other species such as iron, titanium and chromium. It is one of the naturally translucent materials, but can show different colors with different impurities. With hardness of 9.0 Mohs, corundum can scratch almost every other mineral. Corundum is also unusual for its density of 4.02 g/cm3.
Emery:Mineralogically, Emery is an intimate mix of corundum (a natural form of aluminum oxide) with traces of iron-bearing spinels hercynite, magnetite and rutile (titania). It is black or dark grey in color, less dense than transparent corundum with a specific gravity of between 3.5 and 3.8. Crushed or naturally eroded emery is used as an abrasive for general maintenance and polishing of metals, some very fine grits can be used for highly technical polishing, such as preparing metallurgical specimens requiring very close tolerances.
Flint:Flint is a cryptocrystalline form of the mineral quartz. It occurs mainly as nodules and masses in sedimentary rock. Inside the nodule, flint is usually in a dark grey or black color, and often has a glassy or waxy appearance. Outside the nodules, the thin layer is usually different in color, and typically has a white and rough texture. Flint is extremely tough, and can split into thin and sharp splinters by knapping. When struck against steel, a flint edge will produce sparks. So, during the Stone Age, it was used to make cutting tools, ignite fire, and make gunpowder or flintlock. Nowadays it is mostly used as abrasives and building materials.
Garnet:Garnets are categorized as natural silicate minerals. For different species (pyrope, almandine, spessartine, grossular, uvarovite and andradite), garnets have similar physical properties and crystal forms but different chemical components. Garnets naturally occur in many colors such as red, purple, pink, green, blue, orange, yellow, brown, black and colorless. Hard garnet grains are typically used for sand blasting and water jet cutting. They are also applied to other more applications, such as glass polishing and lapping, coated abrasives, organic bonded abrasives, etc.
Olivine:Olivine is a magnesium iron silicate mineral, named for its typically olive-green color, though it may alter to a reddish color from the oxidation of iron. It weathers quickly on the surface because it reacts easily with the (acid) CO2 from the atmosphere. It also fractures easily. Because of its comparatively high density and resistance to erosion under repeated heating and cooling, olivine can be used as the additive in cast iron foundry industry. It’s also a good refractory material. When used as abrasives, olivine gains are widely used for blasting and water jet cutting applications in Europe and Asia.
Pumice:Pumice is a silica based volcanic (pyroclastic igneous) rock with a very porous structure. It’s composed of highly vesicular and rough textured volcanic glass pyroclastic which may or may not contain crystals, with very thin and translucent bubble walls of extrusive igneous rock. It is typically light colored. When used as abrasives, pumice is usually formed in block shape for sharpening or cleaning. Pumice is also ground into powder for polishing and cleaning applications.
Silica Sand:Silica sand is a type of sand composed of 95% silicon. Most silica sand is made up of cracked quartz or silicon dioxide (SiO2) which is the most abundant mineral on the earth and is found in rocks like granite, gneiss, and sandstone. Silica is most commonly found in nature as sand or quartz, as well as in the cell walls of diatoms, well known for its hardness. Silica sand is used for a wide range of applications such as glass manufacturing, industrial casting, sand blasting, concrete producing, ceramics fabrication, slick roads roughening, etc.
Staurolite:Staurolite is a silicate or nesosilicate mineral, mostly opaque, with a white streak, occurring in brown to black prismatic crystals with a resinous to vitreous luster, which are often twinned in the form of a cross. Staurolite is commonly found in metamorphic rocks such as schist and gneiss which are formed when shale is strongly altered by regional metamorphism. Staurolite abrasives exhibit high hardness, low dusting, and low embedment.
Tripoli:Tripoli, also known as rottenstone, diatomaceous earth, D.E., diatomite, or kieselgur/kieselguhr, is a naturally soft silicate or siliceous limestone mineral. Tripoli is made up from the sedimentation of diatoms’ cell walls/shells, and easily crumbles into a fine powder with a white or off-white color. Depending on the granularity, this powder is most commonly used in polishing application or in finishing compound.
Zircon:Zircon is a naturally occurring transparent or opaque mineral in a tetragonal crystalline of zirconium silicate (ZrSiO4), categorized as a group of nesosilicates. The nature color of zircon varies from red, pink, yellow, hazel, black, brown, blue, green or colorless. Zircon is ubiquitous in the Earth’s surface, occurring in igneous, metamorphic and sedimentary rocks. With excellent acid corrosion resistance, and being capable of withstanding high temperature above 3000℃, zircon is mostly used in refractory, ceramics, abrasives, jewelry industries.
Other:Other specialty, proprietary or patented abrasive grain, grit or abrasive material.
The raw abrasive materials or ingots are crushed and sized from blocks to grains and powders ranging from macrogrits to microgrits.
Block:Blocky raw abrasive materials or ingots that are crushed by various crushers, which gradually break them up into smaller or manageable sizes.
Grain:A small, hard particle or crystal of abrasive materials that are typically sized or graded by a series of mesh sieves.
Powder:Much finer grits that are separated by hydraulic flotation and sedimentation or by air classification.
The particle shape of abrasive grains affects their performance in various ways, such as the subsurface damage level and stock removal rate.
Angular:An angular abrasive has sharp but not weak, platy or needlelike edges, which ensure the quickest cleaning rate when removing tightly adhering material or contamination from the substrate.
Blocky:A blocky or rounded abrasive has mostly flat edges. The blocky shape enhances toughness and bulk density of the grain, providing good cleaning rate in most applications, except for those substrates with hard-to-remove contaminants.
Sharp:A sharp abrasive has much sharper edges than the angular one. They are generally required for producing aggressive and fast cutting coated abrasives, grinding wheels, etc.
Cubic:It is generally found in monocrystalline aluminum oxide with a face-centered cubic crystalline structure.
Irregular:A variety of highly irregular shapes are possible through different manufacturing processes for specific applications. Typically, the irregular or crushed shapes are very angular with sharp edges for abrading, cutting or grinding.
Other:Other unusual shapes for abrasive materials.
Abrasives are measured by different grading system standards that define a limited range of particle sizes for each grade. So the grit size designations are not consistent across different grading systems.
ANSI:American grading or grit size standards for abrasive grains. ANSI stands for "American National Standards Institute".
FEPA:European grading or grit size standards for abrasive grains. FEPA stands for "Federation of European Producers of Abrasives Products".
JIS:Japanese grading or grit size standards for abrasive grains. JIS stands for "Japanese Industrial Standards".
ISO:International grading or grit size standards for abrasive grains. ISO stands for "International Organization for Standardization".
GB/T:Chinese grading or grit size standards for abrasive grains.
SAE:"Society of Automotive Engineers" (SAE) grading or grit size standards for sand blasting.
Other:Other unlisted, proprietary, or specialized grading or grit size system.
Bonded Abrasives:Bonded abrasives are made of natural or synthetic abrasive grains which are bound together with a vitrified or resinoid or other bond into a mold usually in the shape of a wheel, then pressed and fired at high temperatures. Bonded abrasives, which can be made from different materials, come in thousands of shapes and sizes depending on the type needed and specific application required, such as cutting-off and grinding wheels, snagging wheels, mounted wheels, segments, honing stones, plugs, cones, etc.
Blasting:Abrasives are used as blasting media, to clean or prepare surfaces prior to applying coatings or to produce a desired surface profile, by propelling very fine bits of material at high-velocity. Blasting is used for finishing, surface texturing, roughening, frosting/ etching, degreasing, deburring, deflashing, descaling, stripping of coatings, and surface preparation of products made of metal, wood, plastic, glass, or other materials. Any small, relatively uniform particles will work, such as steel grits, copper slags, walnut shells, powdered abrasives, even bits of coconut shells.
Cleaning/ Surface Prep:Abrasives are used as finishing media for cleaning and surface preparation products, applied for cleaning, degreasing, de-oiling, texturing, descaling, discoloration removal, roughening, and other surface preparation applications.
Coated Abrasives:Abrasive grains are used to make coated abrasives such as sandpaper and are available in sheets, discs, rolls, belts, pads, flap wheels, and other forms. Coated abrasives are a product of three basic elements: abrasive grains, bond and backing. Abrasive grains can be either natural or synthetic, such as aluminum oxide, silicon carbide, zirconia alumina, garnet, emery, etc. The abrasive grain is adhered to a cloth, fiber, paper or polyester film backing by a resin or glue or other bond. Abrasive grains should exhibit high capillarity for instant adhesion to bonds.
Deburring/ Deflashing:Abrasives are designed or suitable for applications such as removing burrs, sharp corners, part or welding lines and flash (deflashing).
Descaling/ Stripping:Abrasive grits or media are designed or suitable for descaling or coating stripping applications.
Fast Cutting/ Aggressive:Coarse grit abrasives are typically designed or suitable for fast cutting and aggressive applications such as heavy duty cutting or hard materials removal.
Grinding/ Ball Milling:Abrasive media are applied for ball milling or grinding down of a solid material or powder into smaller pieces or finer powders. The material being ground and the media (ceramic bead, hard metal shot, carbide balls or other ball shaped media) are filled in the ball mill for rotating, grinding and mixing by mechanical forces. The hardness of the material or powder being ground determines what kind of media's material will be selected. Media grinding or ball milling is widely used in producing cement, silicate, new type building materials, fireproofing, chemical fertilizer, black and non-ferrous metal, and glass ceramics. Besides, also used to produce alloys from metal powders.
Polishing/ Lapping:Finer abrasive grains are used to make polishing/lapping compounds, coated abrasive lapping films, superfinishing bonded abrasives, etc. Polishing and lapping are characterized by very fine surface finishes, high dimensional accuracy and flatness, and minimal subsurface damage. They are the precision processes applied for mechanical and electronic or semiconductor components, to produce a smooth, bright and lustrous surface.
Tumbling/ Mass Finishing:Abrasives are used as or for the fabrication of tumbling and mass finishing media for the applications of deburring, burnishing, coloring, descaling, polishing or cleaning for parts and components during finishing processes. The selection of shape (such as ball, cone, ballcone, wedge, pin, taper, cylinder, cut wire, diagonal, angle cut, diamond, cube, oval ball, eclipse or ball with flat, crushed grit, pyramid, triangle, and star or tristar) and material (such as natural and synthetic abrasive grain, metal, ceramic, plastic, wood, nutshell, corncob, carbonate or mineral) of tumbling and mass finishing media should be selected depend on particular tasks.
Abrasive Jet Cutting:Abrasive jet cutting process makes use of a focused stream mixed with extremely fine and precise abrasive particles propelled by a high velocity gas or pressure, to cut sheet materials or to remove materials from a surface. Garnet grain is most widely used in abrasive water jet cutting. Aluminum oxide or silicon carbide particles are most commonly used in air abrasive jet cutting. Abrasive jet is capable of cutting heat-sensitive, brittle, thin, or hard materials, and specifically to cut intricate shapes or form specific edge shapes.
Peening:Peening is the process that makes use of a mass and velocity stream of shot, to produce a residual compressive stress at the surface, or to deburr sharp edges without removing material. Each shot striking the surface imparts a small indentation or dimple on the surface of the work piece. Meanwhile, the surface yields in tension due to localized stretching that occurs, while the near surface layer is left in a residual compressive state due to the material’s attempt to restore the surface to its original shape. Induced compressive stress improves fatigue strength. Peening shot and bead can be small metal ball or glass bead.
Specialty:Other unlisted grinding, blasting, finishing, and abrasives applications.