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Bonded Abrasives 101
Abrasive Grains 101
Types of Abrasives
Manufacture of Abrasives
National and Int'l Standards
UAMA Supported Standards
Standard Sands
Coated Abrasives 101
Superabrasives 101


Unified Abrasives
30200 Detroit Road
Cleveland, OH 44145-1967

Unified Abrasives Manufacturers' Association

Appendix 1

Glossary of Terms Commonly Used in the Abrasives Industry

Acid Washed - Abrasive grain washed with acid to remove iron and/or impurities.

Angle of Repose - The greatest angle to the horizontal made naturally by the inclined surface of a pile of abrasive when poured from a designated height. Usually a measure of the ease with which the material will flow.

ANSI - American National Standards Institute - Organization maintaining standards used in the industry.

Apparent Specific Gravity - The ratio of a mass of solid or liquid to the mass of an equal volume of distilled water.

Aspect Ratio - The ratio of the length of a particle to its width.

ASTM - American Society of Test Materials - Organization maintaining technical standards for a wide variety of industries.

Ball Mill - Equipment used to reduce particle size by breaking agglomerations of particles into individual particles and larger particles into smaller ones, and to modify particle shape.

Bayer Process - A process for the purification of bauxite (aluminum ore). The ore is digested with a sodium hydroxide solution which dissolves the alumina and precipitates oxides impurities such as iron, silicon, etc. The solution is then filtered and the alumina precipitated as a hydroxide. This is used as a feed stock for white fused and calcined alumina.

BCI Test - Buck and Company Incorporated - Test equipment for analyzing abrasives for free iron.

Bolting Cloth - Mesh used for making sieves for sifting equipment.

Bonded Abrasives - Abrasive grain used in Grinding Wheel applications.

Bulk Density - Sometimes referred to as "density" or "loose packed density" (LPD). Weight (grams) per volume (cubic centimeters) of loose packed abrasive grain. Generally indicative of the shape of the grain.

CAMI - Coated Abrasives Manufacturing Institute - Organization of coated abrasive manufacturers.

Capillarity - Ability of abrasive grain to be wetted by capillary action. Usually an indication of grain cleanliness.

Cerium Oxide (CeO2) - Naturally occurring deposits are usually a mix of Cerium and other rare earth oxides (REO's), such as Rubidium Oxide and Tantalum Oxide. Color varies from off-white (buff) to reddish brown, depending on the chemical content. Softer than Alumina and Silicon Carbide; primarily used for polishing glass, quartz crystals, etc.

Chemical Composition - A chemical analysis of an abrasive.

Coarse - Composed of comparatively large particles.

Coarse Grading - Abrasive grain with too many large particles. A sieve analysis with too much material retained on the largest opening sieves in the specification.

Coarse Grits - Generally particles extremely large for the abrasive grain size.

Coated Abrasives - Abrasive grain used in the sandpaper industry.

Colloid - A finely divided dispersion of one material in a second continuous phase (usually a liquid) in which the particles range in size from one nanometer to one micron. May be used for very fine polishing or as a feedstock for non-fused abrasive manufacture.

Coning and Quartering - A method for getting a smaller representative sample usually from a larger sample. The grain is arranged into a conical pile and divided into quarters. Alternate quarters of the pile are combined, piled and quartered similarly until a small representative sample is obtained.

Corundum - Naturally occurring Aluminum Oxide.

Crude - Large pieces of abrasive in an ingot form (after furnacing) or after primary crushing.

Crusher - Size reduction equipment causing the separation of a solid into pieces. Some examples are jaw, gyratory, roll, and hammermill.

Crystallography - Description of the size or shape of a crystal. For fused abrasives, usually determined by degree of cooling an ingot after furnacing. For SiC, alpha silicon carbide forms hexagonal crystals. NOTE: Crystallography refers to the shape of the crystal formed, and is distinct from the shape of the actual abrasive granules, which may be modified by crushing, milling, etc.

Density - Sometimes used to describe apparent specific gravity or bulk density.

Dust Fines/Extreme Fines - Particles much too fine for the abrasive grain size.

Electrical Resistance - A method of measuring particle size distribution, used especially for microgrits.

Emery - Naturally occurring mineral, an intimate mixture of corundum and mineralized iron oxide.

FEPA - Federation of European Producers of Abrasives - European organization which maintains abrasive specifications (FEPA F - Bonded) (FEPA P - Coated).

Fine - Composed of comparatively small particles.

Fine Grading - Abrasive grain with too many small particles as specified on a sieve analysis.

Flint - A silica-based mineral often used as an abrasive.

Free Iron - Iron in abrasive grain usually originating from the crushing equipment.

Friability - Relative breakdown of the abrasive grain through attrition (grinding, blasting, milling)

Furnacing - General method for producing abrasive crude either by fusion (alumina based) or electro chemical reaction (Silicon Carbide).

Fusion - Melting of raw materials (generally in an electric arc furnace) to make an abrasive ingot. Generally associated with Alumina based abrasive grains.

Garnet (Al2O3.3FeO.3SiO2) - A naturally occurring abrasive, reddish brown in color, blocky to sharp in shape, slightly softer than Alumina (8 on Mohs scale). Used in a variety of industrial applications.

Grade - Definition of size of abrasive grain.

Grit - Similar to grade.

Hardness - Resistance to denting or scratching usually measured the Moh's scale or Knoop.

Heat Treating - Heating an abrasive grain to impart a certain property (harder, tougher, cleaner)

ISO - International Organization for Standardization- International organization involved with specifications and quality systems.

JIS - Japanese Industrial Standard, published by the Japanese Industrial Standards Committee in conjunction with the Japanese Standards Association.

LPD - Loose packed density. Same as bulk density.

Macrogrits - Generally abrasive grain sizes coarser than 240 or 280 grits.

Mag (Magnetic) Treat - Passing abrasive grain through a magnetic field to remove free iron.

Melting Point - The temperature at which a solid turns to a liquid.

Mesh - Generally interwoven wire screening used to sift or test abrasive grain. Sometimes wrongly used to describe abrasive grain size.

Microgrits - Generally abrasive grain sizes finer than 220 or 240 grits.

Micron - One millionth of a meter. Generally used to define average particles size of microgrits (powders).

Mixed Grits - Generally a condition where two grit sizes are unintentionally mixed together.

Nanometer - One billionth of a meter (one thousandth of a micron).

Netronics - Instrument (Buck and Company, Inc.) Used for measuring free iron.

Packed Density - Another term for tap density.

Particle Size - Average diameter of an abrasive grain.

Pour Density - Bulk density.

Pycnometric Density - Apparent specific gravity tested with a pycnometer.

Refractories Abrasive - Abrasive grain manufactured for the Refractory industry.

Riffle - A sample splitting device used to separate a large sample into a small representative sample.

Rotap - Instrument used to sift abrasive through sieves to obtain a particle size distribution measurement.

Sample Thief - A tubular instrument with a closed, pointed end having holes down one surface used for procuring a representative sample of abrasive grain.

Screen: 1) A sieve. 2) A machine with screening surface(s) used to classify materials by size.

Screen Sizes - Another term for macrogrits.

Sedimentation Sizes - Another term for microgrits.

Sedimentometer - A device for measuring particle size distribution using the time it takes a sample of material to settle a given distance, using Stokes Law.

Sieve - Generally, interwoven mesh mounted on a frame and used for testing or sifting abrasive grain.

Sieve Sizes - Another term for macrogrits.

Sinter - To coalesce into a single mass without actually melting.

Size Distribution - A measured size range of abrasive particles.

Spherical Equivalent - A means of reporting the size of particles regardless of shape based on their volume, in which the particle size is reported as the diameter of a sphere of the same volume.

Standard Sand - An abrasive of a known particle size distribution when tested on a calibrated instrument; used to verify calibration of other test instruments (such as sieves; see Appendix 3).

Surface Treatment - Coatings added to abrasive particles to impart certain characteristics (wetability, flowability, retention).

Tap Density - Generally a bulk density of a packed sample. Generally used for powders.

Test Sieve - A specially manufactured sieve used for testing particle size.

Toughness - Resistance to abrading of abrasive grain.

Viscosity - The resistance of a liquid to shear forces, and thus its resistance to flow.

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