Tribology

Science and engineering ofinteractive surface in relativemotion.

Presented by:Mukut ch. MedhiSomnath DeyDhiru Kamal DekaMd Shaifuddin

Dept. of Mechanical EngineeringTezpur University

Tribology

• Tribology (origin in 1960’s)

Tribology= tribos+logos

Rub

Principle or logic

Brown’s first law of applied Tribology

IF IT'S RUNNING

IT'S WEARING !!!

IF IT'S NOT RUNNING

IT'S PROBABLY WORN!

Tribology

• Two bodies in relative motion .

• Results Friction

oStatic frictionoFrictional heat, resistance against movement

(friction force), loss of energy.

WearoMaterial loss degradation of surface, decreasing

functionality.

Examples of Tribology

• Industrial Tribology– Machine parts/engines

• Lubrication• Oil• Grease

• Friction and wear

• Decreasing performance

Wear Definition

• Most wear is an combination of several mechanisms

Wear Mechanisms

• Adhesive – Low contact pressures – Augmented asperities

• Abrasive – High contact

pressures – Wear tracks

Friction

• Origin of friction– Deforming of the surface : deformation energy– Adhesion of two bodies: non-linear adhesion

hysteresis• Atomic adhesion model• Van Der Waals• Capillary forces

– Electron interactions

• Dynamic friction –static friction

Lubrication

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

Types of lubricants

• Liquid lubricants– Lubrication with oil

• Cooling and removal of debris• Protection against metal-metal contact• Hydrodynamic lubrication• Lowering friction=lowering energy input into the surface.

– Lubrication with grease• Oil in wax• Low cooling effect/no hydrodynamic lubrication• Alternative when oil lubrication is impossible

Types of lubricants

• Solid lubricants and self-lubricating materials– Plastics, PTFE, MoS2, , Graphite

Important properties of lubricants

• Wide range of viscosity

• Little change in viscosity with temperature

• Chemical stability

• Sufficient specific heat to carry away frictional heat

• Low cost

• Easily available

Bearings

• It is mechanical element that permits relative motion between two parts such as shaft and housing.

Ball Bearing

Classification

• Depending on type of frictionSliding contact bearingRolling contact bearing

• Depending on type of forceRadial Thrust

Rolling and sliding contact bearing

Rolling contact bearing and sliding contact bearing

Radial and thrust bearing

Rolling contact bearing

• Deep groove ball bearing

• Cylindrical roller bearing

• Angular contact bearing

• Self aligning bearing

• Taper roller bearing

• Thrust roller bearing

Rolling bearing

Propeller bearing

Water lubricated polymer bearing

Water lubricated bearing

Different types of bearings

Application

• Industrial Process

• Tribology in biological science

• Tribology in engines

Industrial process

• Rolling-Sheet metal

• Wire drawing

• Tube expansion

• Deep drawing

Rolling-Sheet metal

Rolling-Sheet metal

Wire drawing

Tube expansion

Deep drawing

Tribology in biological science

Tribology in engines

• Lubrication of engine

Lubrication of engine

Valve train

Sump1

Sump2

Piston assembly

Crank shaft

Degradation of lubricant

Piston Assembly

Sump

Sump

Piston

Piston Assembly

Extraction of Oil from Top Piston Ring

Solutions to tribological problem

• Trial and error method– Material selection– Parameter selection– Lubricant

• Simulation method– Selection of simulation– Material selection– Parameter selection– Field data

Conclusions

• Tribology is a multi-disciplinary science that is based onto experience and common sense.

• Boiler feed pumps: 49% of the failures causing outages were because of tribological components.

• Friction, wear and failure of tribological components are costing industry billions of dollars

Reference

• www.falexint.com

• www.wikipedia.org

• lqme.sjtu.edu.cn

• www.TRIBOLOGY-ABC.com

• Design of machine elements- V.B BHANDARI

• Fundamentals of Tribology-Basu, Sengupta, Ahuja

Thank You

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