Lubrication and its types

Lubrication and its types

Group members :

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

Lubrication and its types

Topics ..…

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

Lubrication and its types

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

Lubrication and its types

• 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 .

Lubrication and its types

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

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

Lubrication and its types

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

• Classification of lubricants

Lubrication and its types

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

Lubrication and its types

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.

Lubrication and its types

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

Lubrication and its types

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 .

Lubrication and its types

Lubrication and its types

Application of hydrostatic

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

Lubrication and its types

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.

Lubrication and its types

Lubrication and its types

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 .

Lubrication and its types

• Unlubricated vs boundary lub vs hydrodynamic lub

Lubrication and its types

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.

Lubrication and its types

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

lubrication.

. Two surfaces are partly separated, partly in contact .

Lubrication and its types

Lubrication and its types

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 .

Lubrication and its types

Lubrication and its types

Summary : Stribeck curve

Lubrication and its types

Lubrication and its types

Lubrication importance and its cost ….

any questions …

Thank you