Cutting Fluid and characteristics

1. Dr. Shailesh Kumar Dewangan
Assistant Professor
Department of Production Engineering,
BIT Mesra Ranchi
Cutting fluids
Cutting fluids

2. Cutting Fluids
• Cutting fluids, sometimes referred to as lubricants or
coolants are liquids and gases applied to the tool and work
piece to assist the cutting operation
Types of Cutting Fluids
• Most commonly used cutting fluids
Either aqueous based solutions or cutting oils
• Fall broadly into three categories
Cutting oils
Emulsifiable oils
Chemical (synthetic) cutting fluids

3. Functions and supply of a Cutting Fluid
• Prime functions
Provide cooling
Provide lubrication
• Other functions
Prolong cutting-tool life
Provide rust control
Resist rancidity
• Supply
Through pipe with nozzle

4. Heat Generation during Machining
• Carbon – Increase wear resistance, responsible
for basic matrix hardness.
• W, Mo – Red Hardness
10% Tool
10% Work-piece
80% Chip

5. Characteristics of a good cutting fluid
1.Good cooling capacity
2.Good lubricating qualities
3.Resistance to rancidity
4.Relatively low viscosity
5.Stability (long life)
6.Rust resistance
7.Nontoxic
8.Transparent
9.Nonflammable

6. Advantage of using Cutting Fluids
• Reduction of tool cost
– Tool wear
– Tool life
• Increasing speed of production
– Reduce heat and friction so higher speeds
• Reduced Labor cost
– Tool lost longer and required less granding
– Less downtime
– Reducing cost per part
• Reducing the power cost
– Friction reduce so less power supply on machine

7. Cutting fluid's effect on cutting action
1.Lowers heat created by plastic deformation of
metal
2.Friction at chip-tool interface decreased
3.Less power is required for machining because of
reduced friction
4.Prevents built-up edge from forming
5.Surface finish of work greatly improved

8. Methods of application of cutting fluid
• The effectiveness and expense of cutting fluid application
significantly depend also on how it is applied in respect of
flow rate and direction of application. In machining,
depending upon the requirement and facilities available,
cutting fluids are generally employed in the following ways
(flow):
• Drop-by-drop under gravity - Application of a fluid from a can
manually by the operator. In this case, cutting fluids are used as
lubricants.
• Flooding - Most common method. Flow rates depend on application.
• Mist - Supplies fluid to inaccessible areas. Similar to using an
aerosol can (spray paint or hairspray). Fluid droplets suspended in
air provide effective cooling by evaporation of the fluid.

9. Methods of application of cutting fluid
• High Pressure Systems - use specialized nozzles that aim powerful
jet of fluid towards the cutting zone.
• Through the cutting tool system - an effective method. A narrow
passage can be produced in the cutting tool, where it can be applied
under high pressure

10. Types of Fluids
• Cutting oils
• Emulsifiable oils
• Chemical (synthetic) cutting fluids

11. Cutting oils
Cutting oils are generally compounds of mineral oil (petroleum based) to which are added desired
type and amount of vegetable, animal or marine oils for improving spreading, wetting and
lubricating properties. As and when required some EP (extreme pressure) additive is also mixed to
reduce friction, adhesion and BUE formation in heavy cuts.
Active Cutting Oils: Those that will darken copper strip immersed for 3 hours at temperature of
100º C.
•Dark or transparent
•Better for heavy-duty jobs
•Three categories
Sulfurized mineral oils, Sulfochlorinated mineral oils, Sulfochlorinated fatty oil blends.
Inactive Cutting Oils: Oils will not darken copper strip immersed in them for 3 hours at 100º C.
• Contained sulfur is natural
Termed inactive because sulfur so firmly attached to oil – very little released
• Four general categories
Straight mineral oils, fatty oils, fatty and mineral oil blends, sulfurized fatty-mineral oil
blend

12. Emulsifiable oils
• Water acts as the best coolant but does not lubricate. Besides, use of
only water may impair the machine-fixture-tool-work system by
rusting. So oil containing some emulsifying agent and additive,
together called cutting compound, is mixed with water in a suitable
ratio. This milk like white emulsion, called soluble oil, is very common
and widely used in machining and grinding.
• Mineral oils containing soaplike material that makes them soluble in
water and causes them to adhere to workpiece.
• Emulsifiers break oil into minute particles and keep them separated in
water
Supplied in concentrated form (1-5/100 water)
• Good cooling and lubricating qualities
• Used at high cutting speeds, low cutting pressures.

13. Chemical (synthetic) cutting fluids
• These are occasionally used fluids which are water based where
some organic and or inorganic materials are dissolved in water to
enable desired cutting fluid action. The dissolved chemicals include
compounds of sulfur, chlorine, and phosphorus, plus wetting agents.
The chemicals are intended to provide some degree of lubrication to
the solution. Chemical fluids provide good coolant qualities but their
lubricating qualities are less than the other cutting fluid types.
• Also called synthetic fluids
• Stable, preformed emulsions
• Contain very little oil and mix easily with water
• Extreme-pressure (EP) lubricants added
• React with freshly machined metal under heat and pressure of a cut
to form solid lubricant
• Reduce heat of friction and heat caused by plastic deformation of
metal