Desirable Properties of Cutting Fluids/ Cutting Oils

🔗Functions and advantages of cutting fluid
🔗Types of cutting fluid - Water-based, Straight oil based

 

Characteristics of good cutting fluid

The selection of cutting fluid type is very important. It has a direct effect on tool life, productivity, and cost. The selection of cutting fluid varies with the different machining process and conditions. However, it is desirable to cutting fluid have certain properties. The common properties of cutting fluid listed below.

1. Low surface tension and Low coefficient of friction - that ensures the free flow of fluid. Cutting fluid should have excellent lubricating properties. High lubricity fluids are helpful in low-speed machining such as thread cutting, gear cutting. It prevents adhering of chips on the tool and hence the formation of built-up edge chip.
2. Chemically stable (resistant to rancidity) -  it should be chemically stable even in extreme conditions (high temperature and pressure).
3. Large specific heat / High heat absorption capacity - cutting fluid must help to dissipate the heat generated at cutting zone due to friction between tool and work material.
4. Non-corrosive and rust resistant - should not chemically affect the workpiece and tool material (stain, rust). For example, the cutting fluid that containing sulphur additives should not use with nickel based alloy.
5. Visibility - it is better to use transparent fluid in cutting operation. Clear fluid allows the complete vision of cutting action.
6. Nontoxic and odorless – it should not produce any toxic fumes when it comes in contact with the hot surface. Even the small amount of toxic gas has a significant effect on operator’s health; it may cause nausea and vomiting. If the fumes (up to certain density) are produced, it must be odorless. According to olfactory engineering, the odors play a major role in the mood of the person.
7. Less evaporative and stability (long life) – Cutting fluids that dry fast is not economical. It causes frequent maintenance and downtime of machine increases.
8. Smaller molecular size – helps the rapid penetration of fluid.
9. Non-flammable – it must possess high flash point. That reduces the risk of fire.
10. High thermal conductivity:  adequate cooling increases the tool life, and surface finish.
11. Cutting must be easily available at low cost.
12. Chemically neutral and harmless to the machine and operator.
13. Low viscosity - The low viscosity helps to rapid settling of chip and dirt.