Cutting Fluids 210

This class identifies the major cutting fluids and their common uses.

Class Details

Class Name:
Cutting Fluids 210
This class identifies the major cutting fluids and their common uses.
Number of Lessons:
Additional Language:
Spanish, Chinese
Related 2.0 Class:
Introduction to Metal Cutting Fluids 221

Class Outline

  • Objectives
  • The Purpose of Fluids
  • Heat and Cooling
  • Friction and Lubrication
  • The Workpiece and Machining
  • Types of Cutting Fluids
  • Inactive Straight Cutting Oils
  • Active Straight Cutting Oils
  • Soluble Oils
  • Chemical Fluids
  • Semi-Chemical Fluids
  • Selecting a Cutting Fluid
  • Delivering a Cutting Fluid
  • Oil Maintenance
  • Importance of Water Properties
  • Importance of Fluid Concentration
  • Fluid Cleaning and Disposal
  • Health and Safety Issues
  • Summary


  • Describe reasons for using cutting fluids.
  • Describe how heat is generated during cutting.
  • Describe the role of lubrication during machining.
  • Describe how tensile strength impacts cutting.
  • Identify the major categories of cutting fluids.
  • Define inactive straight cutting oil.
  • Describe uses for inactive straight cutting oil.
  • Define active straight cutting oil.
  • Describe uses for active straight cutting oil.
  • Define soluble oil.
  • Describe uses for soluble oil.
  • Define chemical fluid.
  • Describe uses for chemical fluid.
  • Define semi-chemical fluid.
  • Describe uses for semi-chemical fluid.
  • Identify variables that influence cutting fluid selection.
  • Describe ways to deliver cutting fluids.
  • Describe the importance of water quality for miscible cutting fluids.
  • Describe how fluid concentration impacts fluid performance.
  • Identify common fluid contaminants.
  • Identify fluid cleaning methods and disposal concerns.
  • Identify safety issues for cutting fluid use.


  • Metalforming I


Vocabulary Term Definition
acidity The state of having a pH value below 7. Vinegar and lemon juice are examples of acidic substances.
active cutting oil An oil naturally containing sulfur that is released during machining to lubricate the cutting tool and the chip.
alkalinity The state of having pH values above 7. Soap and oil are generally alkaline.
atom The smallest distinguishable unit of a material that maintains that material's characteristics.
biocide A substance that kills germs.
boundary lubrication Lubrication that is provided between the cutting tool and the chip.
built-up edge The unwanted, rough edge on a cutting tool that is created by pieces of workpiece welding onto the tool during cutting.
central system A large reservoir and distribution system that supplies fluid to several machine tools.
chemical fluid A cutting fluid that consists of synthetic materials mixed in water. Chemical fluids do not contain any oil.
concentrate The chemical mixture that is diluted with water to create a suitable cutting fluid.
coolant sump The tank on a machine tool that holds cutting fluid.
defoamer An additive used in cutting fluids to help prevent the development of foam and bubbles to improve the cooling ability of the fluid.
ductility The ability of a metal to be drawn, stretched, or formed without breaking.
emulsifier A substance that allows small droplets of one liquid to be suspended in another liquid.
extreme pressure additive A cutting fluid additive used to help create a film that reduces chip welding under high pressures. Sulfur is an example of an EP additive.
extreme pressure soluble oil A soluble oil that contains additional compounds to increase lubrication under extreme cutting conditions.
fatty oil A group of oils including animal, vegetable, or marine oils, used as additives in cutting fluids to increase lubrication.
filtration The process of removing unwanted matter, usually with a mechanical filter.
flood method A method of fluid application in which the cutting fluid is delivered through nozzles and completely covers the workpiece and the cutting tool.
foaming The action of frothy bubbles being formed in the fluid due to excess air.
friction A force that resists the rubbing of objects against each another.
high-pressure method A method of fluid delivery in which fluid is forced through internal holes in the cutting tool.
inactive oil A cutting oil that releases very little lubricating sulfur during machining.
light-duty machining The machining of easily cut metals at low speeds and light feeds.
machinability The relative ease with which a metal can be machined.
make-up The cutting fluid concentrate additionally needed to make the fluid concentration level correct.
mineral oil A light oil.
miscible fluid A cutting fluid which is a mixture of water and soluble oil and/or chemical agents.
nitrite An additive used in synthetic fluids for rust prevention.
pH A measure of the acidity or alkalinity of a substance.
pH meter An instrument used to measure acidity or alkalinity.
phosphate An additive used in synthetic fluids for water softening.
plain fluid A semi-chemical fluid that contains no additives.
plastic flow The deformation of the workpiece metal just ahead of the cutting tool.
pressure weld To attach the chip to the cutting tool under the high temperatures and pressures involved in cutting.
refractometer An optical instrument used to measure the concentration in a miscible cutting fluid.
ring-distributor method A fluid application method that delivers fluid through small holes in a tube around the cutting tool.
semi-chemical fluid A water-based cutting fluid containing a mixture of chemicals and soluble oil. It is also called a semi-synthetic fluid.
semi-synthetic fluid A water-based cutting fluid containing a mixture of chemicals and soluble oil. It is also called a semi-chemical fluid.
severe machining A machining operation occuring under very high pressures and temperatures.
skimmer A device that uses a rotating wheel to remove unwanted materials from the surface of cutting fluid.
straight cutting oil A cutting fluid that is all oil and that contains no water.
sulfochlorinated mineral oil An active cutting oil containing sulfur and chlorine for improved boundary lubrication.
sulfur A cutting fluid additive used to increase the lubrication under severe machining operations.
sulfurized mineral oil Mineral oil with added sulfur for improved boundary lubrication.
super-fatted fluid A cutting fluid with added animal or vegetable fats for better lubrication.
super-fatted soluble oil A cutting fluid with added animal or vegetable fats for improved boundary lubrication.
surface tension A property of a liquid that is demonstrated as the liquid tries to minimize the area of its surface.
surface-active agent A substance that reduces the surface tension of a liquid. It is also called a surfactant.
surface-active cutting fluid A chemical fluid that contains additives to reduce the surface tension of the fluid.
suspension A mixture in which small particles are dispersed evenly.
synthetic fluid A cutting fluid that is made from chemicals. Synthetic fluids are used mostly for their ability to cool.
tensile strength The maximum stress, or tension, a material can endure before it breaks.
tramp oil Hydraulic oil or grease from the machine tool that has contaminated the cutting fluid.
true solution A type of chemical cutting fluid that contains mostly nitrites, which act as rust inhibitors.
vacuum filter unit A device commonly used to filter cutting fluid. It advances a rolled fabric filter with a vacuum sensitive feeder.
water hardness A measure of the amount of minerals dissolved in water.
water miscible fluid A fluid that can thoroughly mix with water.
wet To cover with a liquid.