CUTTING FLUIDS

CUTTING FLUIDS

Cutting fluids, sometimes referred to as lubricants or coolants are liquids and gasses are applied to the tool and workpiece to assist in the cutting operations.

Types of cutting fluids

            The type of cutting fluids to be used depends upon the work material and the characteristic of machining process.  For some machining process, a cutting fluid which is predominantly a lubricant is desirable.   With other machining processes, cutting fluid predominantly a coolant should be used. Cutting fluids classified in seven main groups. These include water, soluble oils, straight oils, mixed oils, chemical additive oils(sulphurized and chlorinated),a chemical compounds and solid lubricants.

Water : water, either plain or continuing an alkali, salt or watersoluble additive but little or soap are sometimes used only as a coolant. But water alone is, in most cases objectionable for its corrosiveness

Soluble oils: Soluble oils are emulsions composed of around 80% or more of water soap and mineral oil. The soap acts as an emulsifying agent which break the oil into minute particles to disperse them throughout water. The water increase the cooling effect, and the oil provides the best lubricating properties and ensure freedom from rust.  By mixing various proportions of water with soluble oils and soaps, cutting fluids with a wide range of cooling and lubricating properties can be obtained.

Straight Oils:  The straight oils may be
a. Straight mineral oils, kerosene, low viscosity petroleum fractions, such as mineral seal, or higher-viscosity mineral oils,
b. Straight fixed or fatty oils consisting of animal, vegetable, or synthetic equivalent, lard oil, etc.  They have both cooling and lubricating properties and are used in light machining works.
Mixed oils:  This is a combination of straight mineral and straight fatty oil. This blend makes an excellent lubricant and coolant for automatic-screw machine work and other light machining operations where accuracy and good finish are of prime importance.

Chemical-additive oil:Straight oil or mixed oil when mixed up with sulphur or chlorine is known as chemical additive oil.  Sulphur and chlorine are used to increase both the lubricating and cooling qualities of the various oils with which they are combined. Sulfurized mineral oils are commonly used for machined the tough, stringy, low-carbon steels.Chlorinated mineral oils are particularly effective in promoting anti-weld characteristics.
Chemical Compounds:  These compounds consists mainly of a rust inhibitor, such as sodium nitrate, mixed with a high percentage of water. Chemical compounds have grown in favour as coolants, particularly in grinding and on machined surfaces where formation of rust is to be avoided.
Solid lubricants:Stick waxes and bar soaps are sometimes used as a convenient means of applying lubrication to the cutting tool.

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Material	Turning & Boring	Threading	Drilling	Reaming	Shaping, Planning Slotting	Milling
Cast iron	Dry	Dry	Dry	Dry, Tallow, Lard oil	Dry	Dry
Soft steel	Cutting compound, Cutting oil, Soap Water	Cutting compound, Cutting oil, Soap Water	Any Coolant	Cutting Compound	Soap Water, soda water	Soluble, Sulphurized (or) Mineral oil
Hard Steel	Mineral Lard Oil	Mineral Lard Oil	Kerosene, Strong soda water	Mineral Lord Oil	Mineral Lard Oil	Soluble, Sulphurized, mineral (or) Mineral Lard Oil
Brass	Dry	Dry, kerosene, turpentine	Dry	Dry, kerosene, turpentine	Dry	Dry
Bronze	Mineral Lard Oil	Mineral Lard Oil	Dry & any Coolant	Dry & Mineral Lard Oil	Dry	Soluble, Sulpharized (or) Mineral oil
Alum inium	Kerosene	Kerosene	Dry, Kerosene	Kerosene with 25% Soluble Cutting oil	Kerosene	Soluble, Sulphurized (or) Mineral oil, Kerosene
Copper	Mixture of lard oil and Mixture	Dry & Mixture of lard oil, and Mixture	Dry, Cooling Compound Lard oil and temp	Dry & Coolant	Dry	Soluble, Sulphurized oil (or) Mineral oil, Kerosene