🔗Functions and advantages of cutting fluid in metal machining
🔗What are the desirable properties of cutting fluid?
Cutting fluid is mainly divided into
- Water-based fluid
- Straight or neat oil-based fluid
To get variety of objectives like rust inhibition, many additives are added to these cutting fluid. There are also gaseous cutting fluid, the most common gaseous cutting fluid is oxygen and water vapor at the ordinary atmospheric condition.
Water-based cutting fluidCutting fluids for cooling and removing swarf are generally based on water. The main constituent of this type of cutting fluid is water, they are solution of oil in water. Water is a good heat conductor but the water itself not used as cutting fluid because it causes rust and corrosion. The other ingredients are necessary to add in water to create an optimal cutting fluid. The earliest method of improving cooling and lubricating properties of water is by adding soft soap. Now soluble oils are mixed to water to get the desired effect. In which 1-5% soluble oil is mixed with water and form an emulsion. The soluble oil-water mixture possesses excellent cooling properties and some extent of lubricating properties at low cost. The soluble oil emulsion contains corrosion inhibitors and biocide (keep down the growth of bacteria).
In some application, cutting fluid based on the chemical solution is used, but they are not popular. The soda solution is used in grinding operation because it has good cooling effect and flushing action.
Soluble oils cutting fluid: Other base oil is emulsified in water. They show good cooling and lubrication properties.
Synthetic cutting fluid: They are the true solution of alkaline inorganic and organic compound in water and it has no oil. They show very good cooling properties.
Semi-synthetic oil cutting fluid: Emulsion in water with mineral oil and some additional chemical. The properties are in between of those in soluble oil and synthetic cutting fluid.
Straight or neat oil-based cutting fluidWhen oils are used as coolant and lubricant in it undiluted form then it is referred to neat oil-based cutting fluid. In most case, oil does not apply as straight but as a mixture of oils or the mixture of oil with chemicals (such as Sulphur, chlorine, etc.). The straight oil type gives good lubrication but poor cooling. The neat oil-based cutting fluid is further classified into
- Mineral oil
- Straight fatty oil
- Compound or blended oil
- Sulphurised oil
- Chlorinated oil
🔗Types of oil-based cutting fluid
Some other types of cutting fluid are listed below
Pastes or gels and Solid lubricants – In some application cutting fluid are applied in the form of a paste. Eg: in hand operations such as drilling and tapping. The graphite goes under the category of solid lubricants.
Aerosols (mists) – Some cutting fluids are in the form of an aerosol, ie the tiny liquid particle is suspended in air. The main problem with mists is that they cause a health hazard for workers.
Pressurized air and other gases – Compressed air and CO2 are supplied through pipes and aimed at cutting region through the nozzle. Decompressing gaseous give a cooling effect and it blows away the chips.