Principles of lubrication new

Lubrication Oil & Grease

By – Fayek Shakran

Oil Analysis

Principles of Lubrication

Oil & Grease Lubrication

Right lubricant

to the right place,

on the right machine,

in the right amount,

at the right time.

Lubricant storage and handling

Task-Lubricant selection

Course Content

Principles of

Lubrication

Our Industrial Requirement

– Improving productivity & Minimizing waste .

– Reducing costs of Operation .

How ?

Ex-Bearing Failure analysis

When one body slides across another a resistive force must be overcome.

Friction

Force that opposes motion between two surfaces in contact.

Friction is Caused by Micro welds

Types of friction:

a. Static (usually the greatest)

b. Sliding

c. Rolling (usually the least)

Friction

Friction

• Causes of Solid Friction

Factors Influencing Friction

Surface roughness1 Flatter areas2

It is independent of both:

- Speed

- Area of contact

Friction

Lubrication

The principle of supporting a sliding load on a

friction-reducing film is known as lubrication

Lubrication

• prevention of metal-to-metal contact by means of

an intervening layer of fluid

1

2

These lubricants are used to a large extent in the

lubrication of aircraft internal combustion engines

& moving parts.

World Organizations

Lubrication

Type of lubricants

Solid- Semisolid – Fluid

Classification of Lubricants

• Animal

• Vegetable

• Mineral

• Synthetic

These are highly stable at normal temperaturesAnimal lubricants may not be used for internal combustion because they produce fatty acids

Animal and vegetable oils have a lower

coefficient of friction than most mineral

oils but they rapidly wear away steel

Examples of vegetable lubricants are:

Castor oil

Olive oil

Cottonseed oil

Lubricants

All liquids will provide lubrication of a sort, but some

do it a great deal bettor than others.

– Provide high quality products, supported by successful field experience.

– Work to lower maintenance.

- Work to Lower cost of operation through value added services.

– Provide products to help Machine for long operation.

Oil Requirement :

Lubricating oils

• are improved heat dissipation from the friction point

• its excellent penetrating and wetting properties.

Lubricating oils

The advantages of a lubricating oil .

Complex design is required to keep

the oil at the friction point and

prevent the danger of leakage.

main disadvantage Lubricating

oils are used

in

sliding bearings

chains

gears

hydraulic systems

Purpose of Oils

• Oil reduces friction between moving parts– Lubrication – slippery surface between moving parts

– Seal – between piston rings and cylinder surface

– Cool – especially bearings (dissipate heat)

– Clean – contaminates held in suspension (wear particles)

Change oil before winter lay-up so

contaminates are removed and do not

damage the machine during storage

Different lubricants show different behavior regarding these

requirements.

Oil Lubrication

Purpose of Oils

Lubricating oils

• Lubricating oils consist of a base oil and additives which determine their performance characteristics. The additives, however, determine its actual performance by influencing the base oil’s.

• oxidation stability.

• anticorrosion properties.

• wear protection.

• emergency lubrication properties.

• wetting behavior.

• emulsibility.

• stick-slip behavior.

• viscosity-temperature behavior.

Main tasks, remain lubrication and protection against friction and wear.

The additives to

Synthetic oil Engine oil Transmission fluid. Refrigeration oil. Compressor oils.Metalworking fluids and oils. Laminating oils. Industrial hydraulic fluid. Copper and aluminum wire drawing solution. Electrical insulating oil. Industrial process oils. Oils used as buoyants. This list does not include all types of used oil.

These lubricants

are used to a

large extent in

the lubrication.

Mineral & synthetic Oil

Mineral & synthetic Oil

Oils are generally classified as refined and synthetic.

Oils are refined from crude.

Oil while synthetic oils are manufactured.

-Synthetic lubricants are produced from chemical synthesis.

-These oils are generally superior to petroleum (mineral)

lubricants in most circumstances.

-Synthetic oils perform better than mineral oils.

Petroleum (mineral) lubricants are produced from the

refinement of existing petroleum

Synthetic Lubricants

• Because of the high

operating temperatures of

gas-turbine engines, it

became necessary to

develop lubricants which

would retain their

characteristics at

temperatures that cause

petroleum lubricants to

evaporate and break down.

Synthetic lubricants do not

break down easily and do not

produce coke or other deposits

• notable at either very low

or very high temperatures.

• Good oxidation stability

• lower coefficient of

friction permits operation

at higher temperatures.

• The better viscosity index

and lower pour points

permit operation at lower

temperatures

Synthetic Oil

The major is the initial cost,

which is approximately three

times higher than mineral-

based oils.

However, the initial premium is

usually recovered over the life

of the product, which is about

three times longer than

conventional lubricants.

The higher cost makes it

inadvisable to use synthetics in

oil systems experiencing leakage

Advantages of synthetic Oil Disadvantage to synthetic oils

Petroleum Lubricants

Petroleum lubricants stand high in metal-wetting ability, and

they possess the body, or viscosity characteristics.

oils have many additional properties that

are essential to modern lubrication, such as:

-good water resistance.

-Inherent rust-preventive characteristics.

-Natural adhesiveness.

-Relatively good thermal stability.

-Ability to transfer frictional heat away

from lubricated parts.

Characteristics of Lubricating Oils

GravityFlash PointViscosityCloud PointPour PointCarbon-Residue TestAsh TestPrecipitation-number

• The gravity of petroleum oil is a numerical value which serves as an index of the weight of a measured volume of this product

Gravity


Flash Point

1

3

2

Temperature which the oil give off enough vapor to form a

combustible mixture above the surface.

Viscosity

Viscosity a measure of a resistance to flow


Cloud Point4

The cloud point is the temperature at which the separation of

wax becomes visible in certain oils under prescribed testing

conditions.

Pour Point5

The pour point of an oil is the temperature at which the oil

will just flow without disturbance when chilled.

Carbon-Residue Test6

The purpose of the carbon-residue test is to study the carbon-

forming properties of a lubricating oil.

Ash Test


7

The ash test is an extension of the carbon-residue test - The

ash content is a percentage (by weight)

Precipitation number8

The precipitation number recommended by the ASTM

(American Society for Testing and Materials) is the number of

milliliters of precipitate formed when 10 mL of lubricating

oil is mixed with 90 mL of petroleum naphtha under specific

conditions and then centrifuged

Lubricant Additives

-Additives are most effective in overall performance of an oil .

-A poor oil cannot be converted into a quality oil by additives.

-There are limits to the amount of additives that can be added.

additive may function in any of the following three ways:

Protecting lubricated surfaces. Additives coat the

lubricated surfaces and prevent wear or rust

Improving performance. Viscosity index improvers

and antifoaming agents are examples.

Protecting the lubricant itself. Antioxidants reduce

the tendency of oil to oxidize and form sludge.

Oil Viscosity

Viscosity

With lubricating oils, viscosity is one of the most fundamental properties, and much of the story of lubrication is built around it.

viscosity a measure of a resistance to flow

Thick fluids, like molasses, have relatively

high viscosities; they do not flow readily.

Thinner fluids, such as water, flow very

easily and have lower viscosities.

Lubricating oils are available in a wide

variety of viscosities

Viscosity

Multi grade oil

Viscosity

Typical Lubrication Systems

Oil bath lubricationOil injection lubricationCirculatory oil lubrication

Cooling

pump

Oil Lubrication Methods

Gravity LubricationSplash Feed Lubrication

Vibrating pin LubricationOil Bath Lubrication


Pressure Feed Lubrication


Wick Lubrication Ring Feed Lubrication


Boundary Lubrication

When a complete

fluid film does not

develop between

potentially rubbing

surfaces

Stribeck Curve

Mixed Film

Hydrodynamic

Lubrication

Hydrodynamic Lubrication

hydrodynamic

film occurs

when there is

sufficient

lubricant

between the

lubricated

surfaces at the

point of

loading to form

a fluid wedge

that separates

the sliding

surfaces.

Under even

heavier loads

and moderate

to high sliding

speeds, surfaces

deform

elastically and

thin oil films

are "trapped"

between them

Elastohydrodynamic


New device

Oil-Filter


New device

Components of Lubrication Systems

• Plumbing for Lubrication Systems

• Temperature Regulator (Oil Cooler)

• Oil Viscosity Valve

• Oil Pressure Relief Valves

• Oil Separator

• Oil Pressure Gauge

• Oil Temperature Gauge

• Oil Pressure Pumps

• Scavenge Pumps

• Oil Dilution System

Lubricating Greases

Lubricating Greases

• Lubricating greases consist of a lubricating oil, a thickening

agents and one or more additives.

Lubricating Greases

Lubricating Greases

Today’s new-generation greases are expected to do much more than lubricate. They must meet a wide range of demanding performance requirements.

• Long, trouble-free service life, even at

high temperatures

• Rust and corrosion prevention

• Dependable, low-temperature start-up

• Resistance sling and water wash.

The function of grease is to remain in contact with and lubricate moving

surfaces without leaking out under gravity or centrifugal action, or be

squeezed out under pressure.

• Lubricating greases consist of a lubricating

oil, a thickener and one or more additives.

• The thickener is responsible for the

characteristics of the grease

Lubricating Greases

Complex greases generally have a higher drop point.

More resistant to oxidation.

Synthetic thickeners are most resistant to temperature.

Extensive testing is done to verify properties.

The advantage of a lubricating grease over an oil is that it

Remains at the friction point for a longer time.

less effort is required in terms of design.

Its disadvantage is that grease neither dissipates heat nor

removes wear particles from the friction point.

% Weight Loss of Grease Measured

• Typical Grease (Lithium) - 5%

• Water Resistant Grease <2%

• Exceptional < 0.5%

Water, 80oC (175oF)

Grease Packed Bearings

ASTM D1264 (DIN 51807)

WATER WASHOUT RESISTANCE

Lubricating Greases

(1) Machinery that runs intermittently or is in storage for an

extended period of time.

(2) Machinery that is not easily accessible for frequent

lubrication.

(3) Machinery operating under extreme conditions such as high

temperatures and pressures, shock loads, or slow speed under

heavy load.

(4) Worn components. Grease maintains thicker films in

clearances enlarged by wear and can extend the life of worn

parts that were previously oil lubricated.

Lubricating Greases - Uses

Grease Characteristics

viscosity

Bleeding, migrationis

penetration

Contaminants.

Corrosion- and rust-resistance

Dropping point

Evaporation

Oxidation stability.

Pump ability.

High & Low temperature effects.

Grease Compatibility

This is another area in which

different manufacturers

give differing

recommendations.

However, to provide

guidance on the amount of

grease to be added for

different size motors, a

grease weight versus shaft

diameter curve was

determined to provide the

most useful information.

Lubricating Greases - Added

How Much Grease Should be Added?

Grease Lubrication Method

Refilling Lubri-

Cup® with 615

Proper lubrication of bearings is a difficult problem to

tackle. Unless the lubrication technician is able to hear

the sound of the bearing during actual lubrication, it's

a guessing game. Now the guesswork is over.

The Ultra-Lube allows you to hear the voice of the bearing

as it is being lubricated. It easily attaches to a grease

gun, turning it into a sensitive listening device.

The Ultra-Lube provides the user with feedback about the

current lubrication status of components about to be

lubricated.

The Ultra-Lube is attached to and becomes an integral part

of the grease-gun.

Upon connecting the gun to the grease nipple the operator

is able to listen to the electronically amplified noise

through the headset and is able to discern problems

associated with lack of lubricant or too much

lubricant.

No additional procedure is necessary other than to

continue to grease components in the normal manner.

Ultra-Lube

Brass Grease Nipples

Straight

90 Deg

45 Deg

Lubricant storage and handling study

All lubricants are the end product of

much careful research, refining, and

testing.

During storage after delivery, however,

several things can happen to impair

quality.

-Careless handling.

-Contamination.

-Exposure to abnormal temperatures.

-Confusion of stocks.

all these factors can result in wastage,

damage to machinery, deterioration of

lubricants, higher maintenance costs,

and loss of production.

Lubricant Handling/Storage

Outdoor Storage

Outdoor storage should be avoided if possible

Keep bungs tight

Lay drums on their sides

Use drum covers

Before removing the

bungs, dry the

drum heads and

wipe them clean of

any contaminant

Indoor Storage

-Storage temperatures should remain moderate at all times.

-Oil house should be located away from industrial contamination.

-Should be kept clean at all times.

-Regular cleaning schedules being maintained.

-Avoid all unnecessary contacts, use protective equipment to prevent contact.

-Remove promptly any petroleum product that gets on the skin.

-Do not use gasoline, naphtha, turpentine, or similar solvents to remove oil

and grease from the skin.

-Use waterless hand cleaner or mild soap with warm water and a soft brush.

-Use only clean towels, not dirty rags.

-Remove all contaminated clothing immediately.

-Launder or dry-clean it thoroughly before reuse.

-Use protective hand cream, and reapply it each time hands are washed.

-After work hours, use simple cream to replace fats and oils removed from the

skin by washing.

-Wash hands and arms at the end of the work day and before eating.

-Get first aid for every cut and scratch.

-Avoid breathing oil mist or solvent vapors.

-Keep work area clean.

-Clean up spilled petroleum products immediately. Keep them out of sewers,

streams, and waterways.

-Contact the medical staff on all potential health-hazard problems.

Oil & Grease Handling

preventive measures for personnel who regularly handle petroleum products

Machinery Storage Protection

Storage Protection

Equipment amount of time required to store.

-corrosion inhibiting of inactive process.

-type of equipment.

-expected length of inactivity.

-Service time.

Petrochemical

companies will

usually develop

their standards

to take these

criteria.

must ensure that all its products in their

prescribed use and subsequent disposal

shall not create a significant hazard to the

public health or environment.

Company policy

Audit Checklist

9,5% by oils 0,5% by solid lubricants only

90% by greases

selecting the suitable Lubricant


revolution or DN - factor

D = external bearing diameter [mm]

d = internal bearing diameter [mm]

n = revolution per minute [rpm]

dm= medium bearing diameter [mm] = ———D + d

2

DN = ——— • nD + d

2

Dependance of Relubrication Intervals on Tempearture

100

85

70

55

40

Lubrication interval°C

Temperature at the outer ring

l above 70°C the factor 0,5 appliesfor each temperature rise of 15°C

i.e. with a temperature rise from e.g.70°C up to 85°C the service life ofthe grease is cut by half.

l below 70°C the factor 2 appliesfor each temperature drop of 15°C

i.e. with a temperature drop from e.g.70°C down to 55 °C the service life of the grease is doubled.

Lubrication with Solid Lubricants

Deep groove ball bearings with increased clearance

required at:

l high temperatures > + 200 °C

l high temperature variations

l low speed

Desiccant Breather Function

Keeps head space clean & dryDesign varies by manufacturer.

In/out air vents.Air diffuser/oil mist

foam filter.

Press-in mounting, varying

adapter options.

Particulate filter element.

Hydrophilic agent

adsorbs water, indicates condition by

color change.

Second particulate filter

element protects against migration of

desiccant.

Second foam filter stops

oil mist during exhalation, evenly distributes air.

Durable, shock

absorbing housing.

Oil Analysis & Contamination

Oil Analysis - why?

Contamination

• It’s the most frequent problem that affects sample integrity.

– Wear metals

– Water

– Unusual color

– Particular matter

The primary objective of Contamination Management is

optimal system cleanliness.

1. Increased fluid usage life

2. Reduced component wear

3. Less machine down-time

4. Optimal machine performance

Optimal system cleanliness will give you:

All this will result in significant cost savings for your plant.

objective of Contamination Management

Purpose• To give an understanding of the oil analysis program and

what is required to ensure that oil sampling from applicable

equipment is successfully accomplished.

Oil Analysis

Objectives

-Condition Monitoring Program-Improve equipment reliability/readiness-Lower maintenance costs-Reduce resource usage-Maintenance diagnostic tool-predictive maintenance

Methods of Analysis

• Spectrometric

• Viscomentry

• Crackle Test

• Ferrography

• Infrared

Spectrosopy

Elements Tested For

• Aluminum

• Antimony

• Barium

• Boron

• Calcium

• Chromium

• Copper

• Iron

• Lead

• Magnesium

• Molybdenum

• Nickel

• Phosphorus

• Potassium

• Silicon

• Silver

• Sodium

• Tin

• Titanium

• Zinc

Methods of Analysis

Contamination

Wear metals Water color Particular matter

90

80

70

60

50

40

30

20

10

0.002 3.0 6.0

% WATER IN OIL

% R

ED

UC

TIO

N IN

FA

TIG

UE

LIF

E

48

7883

• Mobil Oil evaluation on bearing fatigue life

– 0.002% water reduces fatigue life 48%

– 6.0% water reduces fatigue life 83%

– 0.002% water is 1 drop of water in a quart of oil

Water Contamination Problem

Sampling Methods

• Valve

• Pump

• Drain

Acceptable Contamination Levels

Sensitivity: Main protection

Type of system: Low pressure systems with large clearances

Typical components Ram pumps

Particle

sizes

Range of

counts ISO

> 5 µm 1,000,000 21 /17

> 15 µm 64,000

> 5 µm 250,000 19/15

> 15 µm 16,000

> 5 µm 130,000 18/14

> 15 µm 8,000

> 5 µm 16,000 15/11

> 15 µm 1,000

> 5 µm 4,000 13/9

> 15 µm 250

Sensitivity: Average

Type of system: Low pressure heavy industrial systems

Typical components Gear pumps, manual and poppet valves cylinders

Sensitivity: Important

Type of system: General machinery & mobilesystems. Medium pressure, medium capacity

Typical components Vane pumps, spool valves

Sensitivity: Critical

Type of system: High performance and high pressure long life systems, i.e., aircraft, machine tool

Typical components Industrial servo valves

Sensitivity: Super critical

Type of system: Silt sensitive control system with very high reliability. Laboratory or aerospace

Typical components High perf. servo valves

Air Contaminant

Air can exist in oil in

three different states:

dissolved.

entrained .

foam.

Causes of Excessive Air

Contamination

-When a lubricating oil

becomes contaminated

with water

-loss of antifoam additives

-suction leaks

-poor reservoir design

-using the wrong viscosity

Effects of Air Contamination

Air contamination can have negative effects on the machine and

the lubricant.

Air can damage a lubricating oil by increasing the rate of

oxidation

reducing its heat transfer coefficient and reducing its film strength

Machine wear can be generated by air contamination by several

mechanisms

film thickness become compressible.

In hydraulics, entrained air can create other problems as well,

such as spongy operations, loss of controls and an increased

likelihood of surface deposits in valves.

Contamination Control

Contamination

ISO22/19

21/17

20/15

19/16

18/15

17/14

16/13

15/12

14/11

13/10

12/09

Component Life

Component Life Over Time

----

------------

-----

Clean New Oil

10,000

2,500

25,000

Keep it Clean-Cool-Dry Desiccant Breathers Oil Safe System Color Coding

Storage solutions Personnel training Monitor/improve

Source – Caterpillar Contamination Control Basic Training Program

157.7 lb/yr

78.9 lb/yr

19.7 lb/yr

Total Impact of Lubrication on Costs

Plain bearings

Plain bearings and bushings come in a

wide variety of shapes, sizes, types

of surface contact modes, material

compositions and operating profiles,

including:

• Single-sided

• Double-sided

• Vertical shaft

• Horizontal shaft

• Solid housing

• Split housing

• Thin wall

• Thick wall ..etc

Plain or journal bearings are used

for high radial loads and low- to

high speeds. Typical applications

include turbines, large milling

systems, engine cranks, compressors,

gearboxes, shaft bearing supports, ...

Task-Lubricant selection for plain bearing

Shaft

Rotation

Fluid dynamic pressure

support shaft floating

Oil flow

Groove<= 5μm

performs longer life by no metal contact with shaft to bearing



Under normal operating

conditions, the lubrication

regime is a hydrodynamic

full-fluid film. A

hydrodynamic film occurs

when there is sufficient

lubricant between the

lubricated surfaces at the

point of loading to form a

fluid wedge that separates

the sliding surfaces. In this

state, the lubricated

components do not touch

each another, reducing

friction and wear.

Stribeck Curve. This is represented by Z*N/Pwhere Z = viscosity,N = speed (rpm) P = load.

Z*N/P

If the load or the speed changes, the lubricant viscosity must be

adjusted to compensate for the change.

the following approximation equation gives an estimate of what

the final outcome should be.

u = ∏* d * nwhereu = surface speedd = bore diameter, metersn = shaft speed, revolutions per second∏ = 3.1415

The first step is to estimate the machine’s surface speed

Second step -estimate the machine’s unit surface pressure.

ρ = w/I*dWhereρ = pressure, kN/m2l = bearing width

d = shaft diameterw = load, kN

1 2


This is intended only to be a rough approximation for the sake of illustrating the principles behind lubricant selection.Please consult with a lubricationengineering professional prior toattempting to make any change in the lubricant selection for any actual operating machines

Note:

Once known these values

can be plotted on a table for

a rough estimate of

minimum allowable viscosity

Other considerations

The final lubricant type decision

should include considerations

for oxidation stability, corrosion

protection, wear protection,

water and air separation

properties, etc.


Task 2 – Causes of bearing failure

• Improper Lubrication - 43%– How Much, How Often, What Type, What Thickness,

– What Properties are Important

• Improper Mounting - 27%– Alignment, Work Area, General Practices, Inventory Control

and Storage of Bearings

• Other Lubrication Causes - 21%– Separation in Storage

– Temperature Limit Exceeded

– Moisture Contamination

– Other Contamination

• Fatigue - 9% Ultimate L10 Life Expectancy

64% of Bearing Failures are Lubrication Related IS Not The Whole Story

In the Industry We Serve, Most Bearings Fail Due To Some Form ofCORROSION

Task 3 - Gears Lubrication

• Proper Lubrication with timely addition / replacement plays vital role in maintaining the gear boxes with efficiency and increasing its working life.

• Oil level should be checked in all the gear boxes oil indicators / dip sticks.

• Oil level should be in between the minimum and maximum limits of the dip stick (or indicator).

• Testing of the lubricating oils used to be carried out periodically. The following tests are to be done…

1. Dirt contamination

2. Moisture

3. Volatile materials (Benzene, kerosene, spirit etc,)

4. Viscosity

5. Acidity

6. Alkalinity due to soda (Na2 Co3) etc.,

• Worm gears are used to transmit power

& motion between shafts at right angles

• Worm gears normally consist of a small

diameter steel gear worm and a larger

diameter bronze wheel

• Because of the high degree of sliding (5-

20%), the efficiency of worm gears is

lower than for spur or helical units – ~

75 - 85%

• To MINIMIZE WEAR & MAXIMIZE

EFFICIENCY, synthetic Poly Alkylene

Glycol (PAG)- based lubricants are used

in these applications

Synthetic Gear Oils for Worm Gear Lubrication

Bronze wheel

Steel worm

Benefits in Using Synthetic Gear Oils

Mineral-based gear oils typically have a finite performance life

determined by temperatures (low and high), loads, ambient

conditions

• Synthetic gear oils typically provide the following benefits

over mineral oils:

– Improved oxidative & thermal stability

– Improved viscosity-temperature behavior

– Extension of oil change intervals

– Reduced energy consumption

– Improved gear efficiency

– Reduced oil temperatures

– Savings on maintenance and waste disposal costs

– Reduced vibration

Troubleshooting

Symptom: Oil pressure decrease, oil temp. steady

Cause: …………………………………………

Symptom: Slight drop in oil pressure, steady or slight rise in oil

temp.

Cause: ……………………………………………………

Faulty air-induction systems

Leaking cooling systems

Loose cross-over fuel lines

Abnormal wear rates of moving metal parts

Reprocessing is the most common method of recycling used oil in the U.S. Each year processors treat approximately 750 million gallons of used oil.

Seventy-five percent of used oil is being reprocessed and marketed to: • 43% asphalt plants; • 14% industrial boilers (factories); • 12% utility boilers (electric power plants, homes, etc.); • 12% steel mills; • 5% cement/lime kilns; • 5 % marine boilers (tankers or bunker fuel); • 4% pulp and paper mills; • 6% other.

Oil Recycling

Saves Money

• Oil/lubricant products (Good One)

• Oil/lubricant filters

• Repairs by early detection

By Using

LUBRICATION

Right lubricant is applied

to the right place,

on the right machine,

in the right amount,

at the right time.

Types of Greases

Calcium grease.

Calcium or lime grease, the first of the modern production greases

can lubricate satisfactorily to temperatures around 93 EC (200 EF).

1

lime greasedoes not emulsify in water and is excellent at resisting “wash out.”

manufacturing cost isrelatively low

maximum temperature of around 110 EC (230 EF).

Types of Greases

Calcium complex grease2

Aluminum gre ase.

Aluminum grease is normally clear and produced from high-viscosity oils.

Principles of lubrication new

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