.LUBRICANTS
Lubricant is a material that reduces the friction arising due to the sliding / gliding / rolling / moving of two different components in a machinery.
Friction is an undesirable process that results in:
(i) wear and tear of the surfaces of the moving parts
(ii) loss of enormous energy as heat dissipation
(iii) lowered efficiency of the moving parts
(iv) damage of machine parts as seizure etc.
The process of reducing the friction and wear between the two relatively moving components of the machinery is termed as lubrication.
Lubricantsfunctionto: (Purposeofusinglubricant)
1. Keep moving parts apart
2. Reduce friction (lubricant to surface friction is less than surface to surface
friction)
3. Protect against wear and tear
4. Transfer heat(Gas and Liquid Lubricants)
5. Carry away contaminants and debris
6. Prevent corrosion
7. Seal gasses(when present between moving parts,seal the space through the
capillary force.)
> Mechanism of lubrication
Three important types / modes of lubrication are
(i) thick film lubrication or hydrodynamic lubrication
(ii) thin film or boundary lubrication
(iii) extreme pressure lubrication.
Thick film or Hydrodynamic lubrication: In this, the two moving parts are separated
by a thick film of lubricant, about 1000°A thick. This type of lubrication occurs in machine
parts of low load and high speed such as in clocks, sewing machines (delicate
instruments). The coefficient of friction is low, 0.01 to 0.003.
Thick-film/Fluid-film/Hydrodynamiclubrication
Hydrodynamic lubrication is said to exist when the moving surfaces are separated by the pressure of a continuous unbroken film or layer of lubrication. In this type oflubrication, the load is taken completely by the oil film. The think film does not allowthe two surface to touch each other.The basis of hydrodynamic lubrication is the formation of an oil wedge. When thejournal rotates, it creates an oil taper or wedge between the two surfaces, and the
PROPERTIES OF LUBRICANTS
The fire point of a fuel is the temperature at which it will
continue to burn for at least 5 seconds after ignition by an
open flame.
The flash point and fire point refer to the flammability
characteristics of the fluid being tested. In general the fire
points can be assumed to be about 10ºC higher than the
flash points.
1. Fire Point of Fuel (determine volatility and fire resistance) :
Lubricant is a material that reduces the friction arising due to the sliding / gliding / rolling / moving of two different components in a machinery.
Friction is an undesirable process that results in:
(i) wear and tear of the surfaces of the moving parts
(ii) loss of enormous energy as heat dissipation
(iii) lowered efficiency of the moving parts
(iv) damage of machine parts as seizure etc.
The process of reducing the friction and wear between the two relatively moving components of the machinery is termed as lubrication.
Lubricantsfunctionto: (Purposeofusinglubricant)
1. Keep moving parts apart
2. Reduce friction (lubricant to surface friction is less than surface to surface
friction)
3. Protect against wear and tear
4. Transfer heat(Gas and Liquid Lubricants)
5. Carry away contaminants and debris
6. Prevent corrosion
7. Seal gasses(when present between moving parts,seal the space through the
capillary force.)
> Mechanism of lubrication
Three important types / modes of lubrication are
(i) thick film lubrication or hydrodynamic lubrication
(ii) thin film or boundary lubrication
(iii) extreme pressure lubrication.
Thick film or Hydrodynamic lubrication: In this, the two moving parts are separated
by a thick film of lubricant, about 1000°A thick. This type of lubrication occurs in machine
parts of low load and high speed such as in clocks, sewing machines (delicate
instruments). The coefficient of friction is low, 0.01 to 0.003.
Thick-film/Fluid-film/Hydrodynamiclubrication
Hydrodynamic lubrication is said to exist when the moving surfaces are separated by the pressure of a continuous unbroken film or layer of lubrication. In this type oflubrication, the load is taken completely by the oil film. The think film does not allowthe two surface to touch each other.The basis of hydrodynamic lubrication is the formation of an oil wedge. When thejournal rotates, it creates an oil taper or wedge between the two surfaces, and the
PROPERTIES OF LUBRICANTS
The fire point of a fuel is the temperature at which it will
continue to burn for at least 5 seconds after ignition by an
open flame.
The flash point and fire point refer to the flammability
characteristics of the fluid being tested. In general the fire
points can be assumed to be about 10ºC higher than the
flash points.
1. Fire Point of Fuel (determine volatility and fire resistance) :
No comments:
Post a Comment