lubrication and its types

Lubrication and its types

Group members :

• Amr Mohamed seif el din• Ahmed hassan mira • Akram adel fahmy • Randa Mohamed ibraheem


Topics ..…

• Fricton• Lubrication •Why lubrication is needed•Classification of lubricants• Types of lubrication (in details)


• FrictonIs the force resisting the relative motion of solid surfaces ,fluid layers and material elements sliding against each other .


• Lubrication Lubrication is the process or technique employed to reduce wear of one or both surfaces in close proximity, and moving relative to each other, by interposing a substance called lubricant between the surfaces to help carry the load between them .


•Why lubrication is needed ??? • Friction / Wear

• Heat generation• Increases life of machinery • Reduces energy consumption • Material protection • Sealing


On the basis of its physical state, we can classify the lubricants as follows :-

• Classification of lubricants


Types of lubrication Considering the nature of motion between moving or sliding surfaces, there are different types or mechanisms by which the lubrication is done , They are:

1. Hydrodynamic orThick Film Lubrication2. Hydrostatic lubrication 3. Elastohydrodynamic lubrication4. Boundary or thin film lubrication 5. Mixed lubrication6. Extreme pressure lubrication


1. Hydrodynamic or (Thick Film Lubrication)• is exist when the moving surfaces are separated by the pressure of a continuous unbroken film or layer of lubrication.

• In this type , the load is taken completely by the oil film.• It depends on the relative speed between the surfaces, oil

viscosity, load, and clearance between the moving or sliding surfaces.


Application of hydrodynamic lubrication :

Delicate instruments.

Light machines like watches, clocks, guns, sewing

machines. Scientific instruments .

Large plain bearings like pedestal bearings, main bearing

of diesel engine .

الحساسه او الدقيقه االجهزه

مثل الحساسه العلميه االجهزهالقياس واجهزه الميكروسكوب


2 . Hydrostatic lubrication

• It is essentially a form of hydrodynamic lubrication .

• But the film instead of being self-generated, the separating

pressure is supplied by an external oil pump .

• Hydrostatic lubrication depends on the inlet pressure of oil

and clearance between the surfaces .


Application of hydrostatic

lubrication : This type of lubrication is mainly used in the following areas :• Two stroke engines . • Bigger machines .


3. Elastohydrodynamic lubrication• Is developed in heavily loaded rolling contacts .

• film.

• High pressure results in increasing viscosity of lubricant , which improves load capacity .

• The contacting surface is elastically deformed,distributing the load over a greater area .

Examples of machinery applications that operate under EHL are:

• rolling element bearings, gear teeth and cam contacts (rolling) where high rolling contact loads occur.



4. Boundary or thin film lubrication • Lubrication film is insufficient to separate the contacting

surfaces. • the oil film thickness is so small .

• metal to metal contact occurs between the moving surfaces .


• Unlubricated vs boundary lub vs hydrodynamic lub


This type of lubrication is used in the following areas :

1. A shaft starts moving from rest.

2. The speed is very low.

3. The load is very high.

4. Viscosity of the lubricant is too low.


5. Mixed lubrication. is the transition between Hydrodynamic and Boundary

lubrication.

. Two surfaces are partly separated, partly in contact .


6. Extreme pressure lubrication . This lubrication is for very high press ,temperature, speed sliding surfaces .

. Extreme pressure additives are used along with the lubricants .

. Then form solid surface films of (S,CL and P) , acts as a barrier to reduce friction, wear, eliminate the possibility of welding .

. They are activated by reacting with the metal surface when the temperatures are elevated due to the extreme pressure and friction .


Summary : Stribeck curve


Lubrication importance and its cost ….

any questions …

Thank you

lubrication and its types

Engineering