Cutting Fluid Overview [PDF]

Have you ever thought why liquid is sprayed during a cutting operation? Don’t worry! In this article we will dive into the detailed explanation of cutting fluids. Let’s begin with the definition of cutting fluid.

What is Cutting Fluid?

Cutting fluid also called as Coolant or lubricant is used for improving the cutting condition as well as the life of the tool. It can be in liquid as well as gaseous form. 

cutting fluid

Purpose of Cutting Fluid

The cutting fluid or coolant is used for various purposes, some of them are listed below:

Used to Cool the Tool

With the help of cutting fluid, we can decrease the friction between the tool and the workpiece. Also, we can minimize the heat during the cutting operation. By doing this we see an increase in tool life. Also we get a good surface finish and we can prevent metallurgical damage.

Used for Lubrication

It is used for lubricating purposes. This helps the cutting fluid to chip easily and can be removed from the workpiece.

Used to Decrease Friction

Coolant is used to decrease friction. By doing this we can restrict the heat generation. Hence less power is consumed that increases the tool’s life.

Restrict Thermal Distortion

By using cutting fluid we can restrict the change of properties of the material because of heat.

Used as Cleaner

Coolant or cutting fluid is used as a washing agent. With the help of cutting fluid, we can clear the operation area if there is dust inside the cutting area that results in uneven cutting that’s why we need to clean the cutting area.

Some Other Benefits of Using Cutting Fluid

  • It is used to get a good surface finish.
  • It reduces the tool wear.

Properties of Cutting Fluid

The following are the properties of Cutting Fluid:

  • A cutting fluid has a low viscosity so that it can easily flow above the workpiece.
  • It should have a high flash point so that it can be used at high temperatures.
  • It should be stable at high temperatures.
  • It should have a non-foaming tendency.
  • It should have a high heat absorption rate so that during cutting operation it can easily absorb the generated heat.
  • It should have a good lubricating property to reduce the friction between tool and workpiece so that chips can easily get out from the workpiece.
  • Coolant should not react chemically, it has to be chemically active in nature.
  • It should be odorless to avoid any bad smell even at higher temperatures.
  • It should be transparent so that the operator can easily see the cutting area.
  • It should be harmless to the operator.

Types of Cutting Fluid

Following are the main types of cutting fluid :

  • Soluble Oil
  • Cutting oil
  • Synthetic Coolants
  • Solid Lubricants

Soluble Oil

Soluble oil is a mixture of water, mineral oil, and coupling agents. Generally, we use soap as a coupling agent. Insoluble oil, an emulsion of mineral oil in water is used at the ratio of 1:10 to 1:100 depending on the operation we are performing. In Lathe operation, drilling operation, shaping operation we use this type of cutting fluid.

Cutting Oil

It is a mixture of mineral oil and fatty oil. It is mainly used in hand-cutting machinery. It can be used as a coolant as well as a lubricant for Low cutting and high cutting rates respectively.

Synthetic Coolant

As the name suggests, it contains zero mineral oil, it has a higher cooling rate. Generally, this type of coolant is used in grinding operations.

Solid Lubricant

Solid lubricant means it is in the solid phase, soap bars, molybdenum disulfide, graphite, and the wax stick can be used as a solid lubricants.

Cutting Fluid Applications

Cutting fluid can be used in different purposes which are as follows:

  • As a Coolant
    • Used to cool the cutting tool, chip, and job.
  • As a Lubricant
    • Used for easier movement of the tool on the job and also reduces the cutting force.
  • Used as Lubricant and Coolant
    • Cutting fluid can also be used for coolant and lubrication purposes like Fatty Oil.
  • As a Flashing Action
    • To wash off chips, to get a better surface finish

Selection of Cutting Fluid

  • The selection of Cutting fluid mainly depends on the job material along with tool material.
  • It also depends on which kind of operation do you want to perform.
  • And last but not least it depends on the cooling effect.

Here’s a list of material along with the cutting fluid you should use on these materials:

MaterialCutting Fluid
CI, BrassDry Fluid
SteelCutting oil or Cutting compound
High speed steel waterless cutting fluids
Hard Steel, BronzeMineral Oil

A Detailed Video on Cutting Fluid

Cutting Fluid FAQ’s

Why we use Cutting Fluid?

We use cutting fluids to minimize the heat generation rate and also for lubrication purposes.

What are the types of cutting fluids?

We can categorize a cutting fluid into 4 types which are as follows:
1. Soluble Oil
2. Cutting oil
3. Synthetic Coolants
4. Solid Lubricants

Is coolant a lubricant?

Yes, a coolant can be used as a lubricant for metal cutting purposes.


I hope you are clear about cutting fluids and their types. If you have any questions, feel free to ask in comments.

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2 thoughts on “Cutting Fluid Overview [PDF]”

  1. the point you mentioned about the” properties of cutting fluids”
    the 7th point: Coolant should not react chemically, it has to be chemically active in nature.
    there is a typo, it should be chemically inactive in nature
    otherwise, your content is top notch
    nice work

    • I appreciate your attention to detail, and I’m glad to hear that you find the content to be of high quality. I strive to provide accurate and valuable information. If you have any further suggestions or questions, feel free to let me know.


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