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Removal of material by rubbing.

A mixture of two or more elements, at least one of which is a metal, combined in a solid. The resulting alloy has chemical and mechanical properties that are different than those of the separate elements that comprise the alloy.

Referring to water. An aqueous solution is one made with water.

Single celled, microscopic organisms commonly found in our environment and grow well in organic substances.

Chemical added to a metalworking fluid formulation to mix to restrict the growth of microorganisms. This broad term includes bactericides and fungicides.

Boundary lubrication
A thin layer of lubricant film that physically adheres to the surface by molecular attraction of the lubricant to the metal surface. Examples are fats, fatty acids, esters, and soap.

Built-up edge (BUE)
A piece of work material which has been strain hardened and pressure welded to the cutting edge of a tool.

A turned over edge of metal resulting from certain machining operations.

Chemical coolant
A cutting fluid which does not contain any mineral oil; usually a true solution in water or a fine colloidal solution.

A common extreme pressure (EP) additive used to promote lubrication.

Liquid used to cool the work and tool and to prevent rusting or corrosion; cutting or grinding fluid.

Oxidation of ferrous or nonferrous metals; includes rust, staining, pitting, and etching. The process by which a refined metal returns to its natural state.

A concentration of oil droplets of an emulsion near the surface when the emulsion stands quiescent for a sufficient period of time.

Creep-feed grinding
A grinding process in which large volumes of material are removed in a single pass.

Cutting fluid
Fluid (liquid, gas, or mist) applied to the working part of a tool or cutter to promote more efficient machining; coolant; machining lubricant.

Cutting rate
The amount of material removed in a machining operations per unit of time.

An unnatural condition of the skin.

A method for producing a hole using a cutting tool with flutes or grooves spiraling around the drill body which serve as a conduit for chip removal.

Capable of being deformed when cold.

Emulsifiable oil
A straight oil or blend which contains emulsifier or coupling agent so it will form a stable emulsion in water.

A material containing two types of molecular groups, one of which will orient in water and the other in oil. It will, thus, tie together two dissimilar liquids.

An oily mass in suspension in a watery liquid or vice versa.

EP additive
Extreme pressure additive; see Extreme pressure additive.

Extreme pressure additive
A compound which reacts with the surface of the metal (or tool) forming thin films of metallic compounds (usually, a chloride, sulfide, or phosphate) that have relatively low-shear-strength.

The rate at which the grinding wheel or cutting tool is moved along or into the workpiece

Feed rate
(Drilling) The distance the tool moves per revolution.
(Milling) The maximum thickness of material removed per tooth.
(Turning) The distance the tool moves per revolution of the workpiece.

Feed lines
Spiral pattern produced on work in machining.

Ferrous metal
Refers to iron. Steel, carbon steel, stainless steel, high strength steel, cast iron, and other iron-based alloys are also known as "ferrous metals".

Surface quality or appearance.

The final cuts taken to obtain the accuracy and finish.

Gas dispersed in a liquid causing an increase to the volume of the liquid. Usually seen as bubbles on the surface of the liquid which may break quickly or be quite stable.

Fungi (plural form of fungus)
Aerobic microorganisms consisting of either single-celled yeast, filamentous molds, or more complex structures such as mushrooms.

Galvanic corrosion
Common type of corrosion process in which a potential difference through an electrolyte causes surface attack at the interface of two dissimilar metals.

Gun drill
A long drill with passages for coolant, used for deep holes.

Hydrodynamic lubrication
Lubrication where the viscosity of the lubricant keeps the surfaces separated by a fluid film.

Inverted emulsion
A dispersion of droplets of water in oil produced when a small quantity of water is mixed with a relatively large amount of oil.

The ability of a fluid to lubricate a process.

The relative difficulty of a machining operation with regard to tool life, surface finish, and power consumption.

Fluid added to a system to bring it back to full volume. Make-up should be a mixture of water plus coolant concentrate and not water alone.

Metal forming
An operation designed to alter the shape of metal without producing chips.

A broad term used to refer to the shaping of metal by cutting, grinding, bending, stretching, or stamping.

Metalworking fluid (MWF)
A liquid used to cool and/or lubricate the process of shaping a piece of metal into a useful object. The term most often refers to a water-based fluid.

Minimum Quantity Lubrication (MQL)
See Near-Dry Machining.

Any agent which destroys germs or micro-organisms.

An emulsion of oil in water with emulsion particle size so small that the emulsion appears translucent to transparent; see Semi-synethic fluids.

Mineral oil
Any oil of mineral origin such as petroleum.

Capable of being mixed.

Filamentous microorganisms, composed of many cells, which may grow in metalworking fluids interfering with filtration and clogging pipelines; see Fungi.

Near-Dry Machining (NDM)
Machining with lubricant (often a vegetable oil) applied sparingly as droplets mixed with a flow of air. Chips and parts come away almost dry to the touch. There is no excess lubricant to recover, recirculate, or recycle. Also known as Minimum Quantity Lubrication (MQL).

Near-Dry Sawing (NDS)
Sawing with lubricant (often a vegetable oil) applied sparingly as droplets mixed with a flow of air. Chips and parts come away almost dry to the touch. There is no excess lubricant to recover, recirculate, or recycle.

Nonferrous metals
Any metal the is not based on iron, such as aluminum, titanium, copper, brass, bronze, lead, zinc, and tin.

Oil emulsification
The property of a metalworking fluid that determined its capacity for emulsifiying or dispersing oil, typically tramp oil.

Organic compound
Substances containing the element carbon; most contain hydrogen, and many contain oxygen, nitrogen, and other elements as well. Simple oxides of carbon are excluded (e.g. carbon monoxide and carbon dioxide).

Peripheral speed
The speed of any point on the surface of the work (cutter for rotary tool).

Rapid cooling of heated metal for the purpose of imparting certain properties, especially hardness.

Revolutions per minute.

Semi-synthetic fluid
A metalworking fluid concentrate with moderate to low content of mineral oil (typically 5-30%). Generally contains a significant amount of water (30-60%). These are sometimes known as "preformed emulsions".

Soluble oil
A metalworking fluid concentrate with high oil content (50-80%) and little or no water content. As sold it consists solely of oil, emulsifiers, and oil soluble lubricants, corrosion inhibitors, etc. When mixed with water it creates an emulsion that is milky in appearance. These are sometimes known as "emulsion coolants".

A variety of operations in which a part is formed from a flat strip or sheet stock through the use of a forming die set.

Stress corrosion
Corrosion facilitated by high residual surface stress imposed by machining or grinding operations.

Sulfo-chlorinated oil
Cutting oil containing sulphur and chlorine.

A common extreme pressure (EP) additive used to promote boundary lubrication.

Surface active agent
Materials capable of lowering surface and interfacial tensions. See "Wettability".

Metal fines and grinding wheel particles generated during grinding.

Synthetic fluids
A metalworking fluid that contains no mineral oil. Some synthetics are totally water soluble (chemical solutions) which others are emulsions of water insoluble, synthetically derived lubricants (synthetic emulsions).

A method used to cut of form threads inside a predrilled hole.

To form a screw thread on the outer diameter of a cylindrical object, such as a pipe.

Tool life
A measure of the length of time a tool will cut satisfactorily.

Tramp oil
Oil which is present in a metalworking fluid mix and is NOT from the product concentrate. The usual sources are leakage into the cutting fluid system from hydraulic or lubrication systems of the machine tools.

Machining on a lathe or turning center with single point cutting tools.

Up milling
Opposite of climb (down) milling. The cutting tool rotates against the direction in which the workpiece is fed; the chip starts out this and gets thicker as the cut progresses.

The internal resistance to flow exhibited by a fluid, a property that varies with temperature.

Viscosity index
A means of expressing the relationship between viscosity and temperature.

Volatile Organic Compounds.

Water hardness
The combined calcium and magnesium content of water. Usually expressed as parts per million (ppm) of calcium carbonate (CaCO3).

Loss of material from a surface area due to rubbing.

The relative ease with which a liquid spreads over a surface.

Wetting agent
An additive which reduces surface and interfacial tension and facilitates spreading of a fluid over a surface.

The part being machined.

Work hardening
The Hardening process which may occur during cold working or machining; stain hardening.

Mostly single celled fungi. These are larger than bacteria, and either round r oval in shape.