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TOSTUDYFRICTIONCOEFFICIENTANDWEARRATE

TESTINGOFALUMINIUMANDCOPPERSLIDING

AGAINSTSTEEL

OF

LAB-I

Under the Guidance of

DR. Balwinder Singh

ER.SURINDER SINGH KHELA

(Lab In charge)

Submitted by

Anurag Goyal

Regd. No:-1168425

M.Tech Production Engg.

4th

Semester

DEPARTMENT OF MECHANICALENGINEERING

PTUGIANI ZAIL SINGH COLLEGE OF ENGINEERING &

TECHNOLOGY

BATHINDA

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ACKNOWLEDGEMENT

First of all I wish to thank Almighty God for having given me an opportunity to work

under my guide who always made work interesting. It is my proud privilege to express

regards and sincere thanks to Dr. BALWINDER SINGH SIDHU and Er. SURINDER

SINGH KHELA for allowing us to perform the Lab work in my college. I wish to

express my sincere thanks to him for his unfailing inspiration, whole-hearted cooperation

and painstaking supervision, through discussions, criticism and suggestions given by him

during the entire period of this work. Without his timely and untiring help, it would have

not been possible to perform this lab work. I also thank to the entire staff for their help,

inspiration and moral support throughout which went a long way in bringing out this

work from conception to completion.

In the end, I wish to express my deep sense of gratitude to my family, for supporting and

encouraging me at every step of my work. It is the power of their blessings, which has

given me the courage, confidence and zeal for hard work.

ANURAG GOYAL

Roll No-1168425

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INTRODUCTION TO WEAR AND WEAR TESTING MACHINE

Wear is the damage done to a solid surface, generally involving progressive loss of

material. It can occur when two surfaces in contact with each other and usually underload, move relative to each other. In most of the cases, one surface is stationary and the

other move relative to the stationary relative to it (stationary one) by the rolling (as wheel

runs along a track), sliding (various types of linear and reciprocating motions) and mating

(as in the gear drives) action between the parts. Another type of wear is known as

"fretting". It results from two surfaces rubbing against each other with a reciprocating or

oscillatory motion of very small amplitude and high frequency.If one surface is slid overanother then the asperities come into contact and there is a possibility that wear can

occur.The breaking of the entire little junction can cause material removal.For examplethe main reasons for frequent change of car engine oil is that it becomes contaminated

with hard debris particles that can wear out the engine components. It is used for a wide

variety of materials including metals, polymers, composites, ceramics, lubricants, cutting

fluids, abrasive slurries, coatings, and heat-treated samples. For testing the wear

properties of different materials wear test for the material test for that material specimen

is conducted on the PIN-ON-DISK-TESTER.

The Pin-On-Disk Tester is used to test the friction and wear characteristics. The test is

performed by rotating a counter-face test disk against a stationary test specimen pin or

ball.The TR 20 Series comes with the WinDucom software for data acquisition

and for displaying results such as wear, frictional force, RPM and temperature(optional)

for engineering surfaces.

Using the WinDucom Data Acquisition System, a PC acquires test data

Online and displays it in several ways. Graphs of individual tests can be printed. Results

of different tests can be superimposed using the WinDucom Comparative view

feature for comparative viewing of results.

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Mechanism of wear

When two surfaces slide or roll against each other under load, two forces come into play:

1) The load which acts normal to the surfaces in contact. It exerts a compressive force on

the materials (there is a similarity here with cold working) and is usually more

concentrated in the case of a rolling contact.

2) A force exerted by the machine in the direction of motion.

When these two forces combine this effects to work-harden the softer surface or perhaps

both surfaces, to cause plastic deformation of the softer of the two materials or when

junctions occur, to dislodge particles from the more wear-vulnerable of the two surfaces

and in the of abrasive material, grooves are ploughed into the softer material.

There in the contacting surfaces three types ofwear took place:

a) Adhesive wear.b) Delamination wear.

c) Abrasive wear

Adhesive wearAdhesive wear is caused by the strong adhesive force that develops between mating

materials. Prior to the surfaces beginning to move relative to each other, minute areas of

contact between the mating surfaces become joined together (these are known as

junctions). If, when the machine applies a force to break these junctions, the resulting

stresses in the metals are small, only small fragments of the metals become detached.

Delamination wearDelamination wear is the result of cracks forming below the surface and propagating to

link up with other cracks. They are the result of the sub-surface strain gradient caused by

the load and the anti-adhesion force and are aggravated by fatigue or defective material.

As a result, sub-surface deformation occurs and material becomes detached as wear

debris of a platelet or laminated form.

Abrasive wear

Abrasive wear is the result of one very hard material cutting or ploughing grooves into a

softer material. The harder material may be one of the rubbing surfaces or hard particles

that have found theirway between the mating surfaces. These may be foreign particles

or particles resulting from adhesive or delamination wear. It may be possible to arrest

this effect by removing the debris. Otherwise, they may lead to rapid deterioration and to

machine break-down. So to prevent it is advisable to give the harder of the two surfaces a

finer finish to eliminate asperities that can plough into the softer material.

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Factors affecting wearThe degree of wear that occurs is the result of the inter-play of a number of factors that

apply in a given situation. The correlation between these factors has been the subject of

much research with results that are not always applicable to all material combinations,

particularly the relationship of the wear rate and the load, the speed, the coefficients of

friction and of adhesion, hardness and tensile and yield strength. An approximateindication of how load (W) and hardness (H) affect the wear rate (Q) is given by the

following formula

K is a "wear coefficient" of the system and is dependent on many of the factors described

below:

Q = KW/H

The factors affecting wear have been grouped under:

LoadingLoading may be anything from low to high, depending on the application. It may be

Unidirectional or reversing, continuous or intermittent. It governs the friction and

adhesion resistance. It therefore has great influence on wear. In a sliding wear situation,

wear rate increases with load.

VelocityVelocity, like loading, can be anything from low to high, unidirectional or reversing,

continuous or intermittent. It is one of the factors that affect the erosion of the oxide film

although, in some cases, speed has little effect on wear. In other cases it increases the rateof wear and in yet other cases it reduces it. This is because the effect of speed is related to

other factors such as lubrication and the temperature it generates by friction.

FatigueReversing or intermittent loading result in repeated stressing and un-stressing which

gives rise to fatigue. It is particularly prevalent in rolling contact as in ball bearings and

gears and may also be caused by the hammering action of cavitation. Fatigue may in time

lead to the formation of cracks at or below the surface and hence ultimately delamination

wear. Fatigue is greatly affected by surface conditions such as hardness and finish.

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LubricationThe object of lubrication is to reduce friction and the tendency to adhesion and to

mitigate their effects. There are various types of lubrications such as hydrodynamic

lubrication (in which the mating surfaces are separated by a fluid film), hydrostatic

lubrication (in which the lubricant is supplied under pressure and is able tosustain higher load without contact taking place between the surfaces).

Surface finishSurface finish affects wear: A well-polished surface finish - say less than about 0.25 m

rms provides more intimate contact between the surfaces. This results in more interaction

between them and may lead to local weld junctions .Lubricants also tend to be swept

away between smooth surfaces If, on the other hand, the surfaces are too rough - say 2m

rms - the asperities will tend to interlock resulting in severe tearing. Most machined

finishes, however, fall within an intermediate range of surface finish. It is advisable to

give the harder of the two surfaces a finer finish to eliminate asperities that can ploughinto the softer material.

Elastic propertyThe elastic properties of the softer of two mating materials ensure that deformation can

take place under stress without rupture occurring, resulting in delamination.

HardnessWhen comparing the wear resistance of different materials, the harder materials are often

found to be the most wear resistant. It was thought therefore at one time that wear was

inversely proportional to the hardness of the surface being worn away. The relationshipbetween wear and hardness is not so clear cut, however, as more recent researchers have

found. Harder materials do not imply lower adhesion and metal transfer. Hardness is an

important factor in wear performance, its role is more complex and this is basically

related to the structures materials involved. It is evident that the combination of one hard

and one less-hard material is an important feature of a successful matching pair. The hard

surface controls the interaction and the softer surface conforms. The softer material is

able to embed hard abrasive particles thereby minimising damage to the surfaces

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WEAR TESTING MACHINE WORKING PROCEDURE

The Wear and Friction Monitor (Pin/Ball on Disc Tester) records wear and friction in

sliding contact type materials in dry and lubricated conditions. Tribological instrument is

specifically designed for fundamental wear and friction characterization. Experiments are

carried out using a pin-on-disc set-up. A cylindrical pin (both ends flat) can slide on ahorizontal surface (disc) which rotates using the power from a motor. A circular test disc

is fixed on a horizontal plate which can rotate and this rotation (rpm) can be varied by an

electronic speed control unit. A vertical shaft connects the horizontal plate with a

stainless steel base plate. The alignment of this vertical shaft is maintained properly

through two close-fit bush-bearings in such a way that the shaft can move axially. To

provide the alignment and rigidity to the main structure of this set-up, four vertical

cylindrical bars are rigidly fixed around the periphery to connect horizontal plate with the

stainless steel base plate. The whole set-up is placed on a main base plate which is made

of mild steel (10 mm thick). The mild steel main base plate is supported by a rubber

block (20 mm thick) at the lower side. A rubber sheet (3 mm thick) is also placed at theupper side of the main base plate to absorb any vibration during the friction test. For

power transmission from the motor to the stainless steel base plate, a compound V-pulley

is fixed with the shaft. A cylindrical pin (4mm-12mm diameter) of material to be tested is

fitted in a holder and this holder is subsequently fixed by an arm. The contacting foot of

the pin is flat so that it can easily slides on the rotating test disc. The arm is pivoted so

that it can rotate horizontally and vertically with negligible friction.

The TR 20 Series (Company model name) comes with the WinDucom software for data

acquisition and display of results with the help of software created by the company in

graphical format. This data acquisition helps the users measurement of:1. RPM

2. Wear

3. Frictional force

4. Temperature (optional)

S.No Parameters Unit Min. Max Remarks

1. Pin Size (specimen) mm 03 12 Diameter

2. Disk Size mm 165 x 8 Circular

dia

3. Disk Rotation RPM 200 2000

4. Normal Load N 5 200

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Materials Under Wear Test (Al-Cu)

In this experiment the friction and wear of copper and aluminium are investigated

experimentally using a pin-on-disc apparatus. In the experiment the copper and

aluminium pin slides on mild steel disc at different normal load conditions 20, 25, and 30

N. Experiment is also carried out at disk rotating at the 200 rpm. The effects of duration

of rubbing on the friction coefficient of copper and aluminium are investigated. It is

found that during friction process, copper or aluminium specimens takes less time to

stabilize as the normal load or sliding velocity increases. Within the observed range,

friction coefficient decreases when applied load is increased while it increases when

sliding velocity is increased for both copper and aluminium. In general, wear rate

increases with the increased normal load and sliding velocity. Finally, as a comparison, it

is found that friction coefficient and wear rate of copper are much lower than that of

aluminium within the observed range of normal load and sliding velocity. Normal load

and sliding velocity are the two important parameters that indicate the performance of

different metals. Aluminium based alloys can be used in applications where corrosionis a problem. Aluminium alloys are used as bearing materials where low friction is

required. Aluminium and their alloys can be used as a coating material to steel bearing

due to their superior wear properties. In this experiment the influence of rubbing of

aluminium and copper is studied with the mild steel specimen.

Aluminum

Physically, chemically and mechanically aluminum is a metal like steel, brass, copper,

zinc, lead or titanium. It can be melted, cast, formed and machined much like thesemetals and it conducts electric current. In fact often the same equipment and fabrication

methods are used as for steel. Hardness of the value between 60-70 (brinell).Aluminum is

a very light metal. Aluminum naturally generates a protective oxide coating and is highly

corrosion resistant. Aluminum is an excellent heat and electricity conductor and in

relation to its weight is almost twice as good a conductor as copper. Aluminum is ductile.

Due to low density and high strength used to make automotive parts such as pistons, and

is also corrosion resistant used to make cans, good conductor of heat and electricity used

in electrical equipments such as cables. Alloy of aluminum is much more preferred over

it due to improved properties such as duralumin.

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Copper

Copper is an excellent electrical conductor. Most of its uses are based on this property or

the fact that it is also a good thermal conductor. It is a ductile metal. Copper is a metal

have a hardness of 40-50 (brinell). Copper is less reactive metal that does not means it is

non-reactive but as compared to the ferrous metals it is less reactive if compared toaluminum it is more reactive. Copper is a ductile metals and it can be used for pipes and

drawn it can be drawn into wires. Copper is a tough metal suited to make things which

can resist the load conditions. Copper can be combined with other metals to make alloys.

The most well known are brass and bronze. Copper when used with other materials

possess harder and strengthened properties. Copper due to its more density that is why

the wear rate of the copper is very less. Its use is mainly in the el ectrical equipments and

used in pipes and due to the property malleability and ductility it can be easily bended at

the end corners.

Comparison between the properties of the Al-Cu

Copper has higher conductivity than aluminum. Copper has relatively high tensile strength (the greater stress a component can

wear without any tearing), and the density of the copper is three times to that of

the aluminum and copper can be easily soldered.

Copper is much more expensive and heavier than that of the aluminum.

AS the conductivity of aluminum is less still its lighter weight makes it use for thelong span of time as compares to the copper and the wires of aluminum are much

more flexible than that of the copper.

Heat transfer coefficient of the copper is very much more than that of the copperand the pipes made from aluminum have to be highly thickened that is

strengthened otherwise they burst at high pressures this mainly affects the strength

of aluminum.

Copper effects on the oxide formation more as compared to that of the aluminumas the aluminum material does not effect much as the formation of the oxide layer

on the aluminum surface is non corrosive or we can say as less reactive as

compared to that of the copper.

http://showgloss%28%22cond%22%29/http://showgloss%28%22allo%22%29/http://showgloss%28%22bras%22%29/http://showgloss%28%22bron%22%29/http://showgloss%28%22bron%22%29/http://showgloss%28%22bras%22%29/http://showgloss%28%22allo%22%29/http://showgloss%28%22cond%22%29/

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Wear test of Aluminum and copper

The standard samples (pins cylindrical shape) have been prepared (8mm X 25 mm)

from the machining having different wt. of the materials.

Pictorial view of the sample is in the figure below:

Pictorial view casting samples used for wear test

Dry sliding wear tests for the aluminium & copper have been conducted using pin-on-

disc machine model TR20 supplied by M/S Ducom , Bangalore (India). The tests havebeen conducted in normal atmosphere. Wear tests have been conducted using cylindrical

samples (8mm X 25 mm) that had flat surfaces in contact region and the rounded

corner. The pin is held stationary against the counter face of a 100mm diameter rotating

disc made of steel having a hardness of 65 as provided on pin-on-disc machine. The wear

tests have been conducted under the three normal loads 20, 25, 30N and at fixed sliding

speed of 1.5m/s. Pin weight loss has been measured at intervals of 15 minutes to

determine wear loss. Weight loss data has been noted and been compared with the initial

weigh of the sample and respectively the weight loss can be noted down depending upon

the difference this helps us to find the wear or erosion that is the wear loss occurred. The

pin is removed from the holder after each run and properly cleaned before again use. Theweight loss has been taken in a digital balance having least count of 1mg. The pin weight

is measured after every 15 min of sliding and three data points have been taken in a total

duration of 45 min for a particular sample Disk has also cleaned after each run to remove

debris. The friction coefficients have been determined from the friction force and normal

loads.

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Graphical Repersentation of copper and aluminum

samples.

Below graph shows the variation of cumulative wear volume with sliding distance under

different loads and at fixed sliding velocity of 1.5m/s aluminium and copper. It isobserved that the volume loss increases linearly with increasing sliding distance.

However the cumulative volume loss of copper is lower than that observed in Al.

Below graph shows the variation of cumulative wear volume with normal applied loads

& volume loss is increasing with increasing normal loads:

sample of aluminum sample of copper

Comparison of wear rate as a function of normal load of 20N

(Sliding velocity- 1.5 m/s)

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sample of aluminum sample of copper

Comparison of wear rate as a function of normal load of 25N

(Sliding velocity- 1.5 m/s)

sample of aluminum sample of copper

Comparison of wear rate as a function of normal load of 30N

(Sliding velocity- 1.5 m/s)

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Results obtained from graphs:

In the experiment the readings are taken from the graphs and the weight is reduced or we

can say the reduced volume of the samples after sliding in dry condition with the steel

disc.

In this the parameters used are:

Velocity (v)V = DN (Where N=200(approax), dia of the disc =165 X 8mm)

60

From this the value of V=1.32 or 1.5m/s

Weight in kg and the weights are 2kg,2.5kg,3kg (these are used in Newtons,Where 1kg=9.81)

S.NO Velocity

(m/s)

Time Weight

(N)

Aluminium sample Copper sample

Initial

weight

Final

weight

Diff.

(wt.

loss)

Initial

weight

Final

weight

Diff.

(wt.

loss)

1.

1.5 m/s

(constant)

i.e. no

change in

velocity

15

min

At

one

load

cond.

20 6.8599 6.8490 0.0109 22.6385 22.6297 .0088

2.

25 6.8490 6.8335 0.0155

22.6297 22.6166 .0131

3.

30

6.8335 6.8217 0.0118 22.6166 22.6006 0.416

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Study Effect of Friction coefficient of the Aluminum and

Copper

Friction coefficient of copper varies with duration of rubbing and these variationsat different normal loads and reference study *Corresponding author (DewanMuhammad Nuruzzaman)Experiments were carried out at sliding velocity 1 m/s, 1.5m/s and 2m/s. In the

experiments, copper pin was sliding against steel disk. There are various curves shown

for normal load which shows that at early stage when the samples are rubbing against the

steel plate friction coefficient is 0.27 and after that it increases very steadily up to 0.35.

Over duration of minutes, friction coefficient becomes steady and for the rest of the

experimental time it remains constant. Friction is low at the early stage of rubbingbecause of a layer of foreign material on the disc. At early stage of rubbing, oxide layer

separates the contacting surfaces and after initial rubbing, the deposited layer breaks up to

make true metallic contact. After the running-in process for certain duration, the surface

roughness and some other parameters reached to a steady state value and for this reason,

there is no change in friction with time. Under normal load conditions results are shown

by curves and the applied normal loads 10, 15 and 20 N respectively. During friction

process, roughness and other parameters may reach to a certain steady level earlier when

the applied load is increased.

Variations of friction coefficient with duration of rubbing and in the experiments, Whenthe aluminium is mates with the steel disc friction coefficient is 0.48 at the initial stage of

rubbing and after that friction coefficient increases steadily up to 0.55 which remains

constant till experimental time. For the applied normal load applied normal load is 10, 15

and 20 N respectively and the sliding velocities for the procedure are 1m/s,1.5m/s and

2m/s. Study shows that normal load increases from 10 to 20 N, coefficient of friction

decreases from 0.35 to 0.20 and 0.55 to 0.37 for copper and aluminium respectively.

These results are supported by the findings ofDewanshow that as the load increases,

friction coefficient decreases within the observed range. It is observed that for identical

conditions, copper shows much lower friction than aluminium.

35Friction coefficient varies with rubbing time and this variation at different slidingvelocities is shown. In the experiment, copper mated steel disc at normal load 15 N.

Results are shown by curves 1, 2 and 3 for 1m/s.1.5m/s and 2m/s respectively. Similarly

the curves show the results for aluminium and the curves also plot the relation between

these curves for the co-efficient of friction at normal load condition.

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Friction coefficient related to different velocities.

Friction related to samples (Al-Cu)

Friction related to normal different loads

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Conclusion

From the experiment and study the conclusion obtained:

Wear rate increases with the increase in normal load and sliding velocity for bothcopper and aluminium. At identical condition, wear rate of copper is much lower

than that on aluminium for the observed range of normal load and sliding velocity.

When the material is loaded lightly or the material is under the action of lesserforces then the wear rate of aluminium.

Friction coefficient decreases with the increase in normal load while it increaseswith the increase in sliding velocity for both copper and aluminium. At identical

condition, friction coefficient of copper is much lower than that of aluminiumwithin the observed range of normal load and sliding velocity.

Within the observed range of normal load and sliding velocity, friction coefficientincreases with the increase in rubbing time and after that it becomes steady for

both copper and aluminium. It is found that during friction process, copper or

aluminium disc takes less time to stabilize as the normal load or sliding velocity

increases. Moreover, the time to reach steady friction is different for copper or

aluminium disc depending on applied normal load or sliding velocity.

.