DEPARTMENT OF CHEMICAL AND MATERIALS AND

METALLURGICAL ENGINEERING

CORROSION AND TRIBOLOGY

MMEE 411

FRICTION LAB

KATSO MABENGANE 19000659

JEREMIAH MOLALETSI 190001165

SUBMISSION DATE;20/10/2022

LECTURE; PROF ENOCH

ABSTRACT
Friction is the resistance offered by the surfaces that are in contact when they move past each
other as a result the concept of friction is continuously applied in everyday life such as being
able to write on a paper using a pen or even simply walking. One of the aims of this experiment
was to show that friction is proportional to the normal force as well as to determine the
coefficients of friction between various material. The other aim was to determine the angle of
friction of various material on a steel plane as well as to verify that the force required parallel to
an inclined plane to move a body up the plane corresponds to the friction coefficient (or angle)
already found. As a result this experiment was performed in 2 parts where different material
blocks being aluminum , steel, brass and nylon were subjected on an inclined plane and on a
horizontal plane. The results from graph 3.1 and graph 3.2 show that the sliding force and the
normal force are directly proportional to each other that is an increase in one will effect an
increase in another. From all the material blocks nylon stood out with the lowest coefficient
number which infers that nylons slides as ease with stainless steel. The force used or required to
initiate motion in nylon is far less than in steel. Ideally friction coefficient should not be affected
by change in normal force which is not the case in practical sense. It is also shown that the static
friction for all the blocks is higher than the sliding friction which shows that the force required to
move static objects is far greater than those in motion. Lastly the results show that an increase in
the angle of plane reduces the friction coefficient as well as both the normal force and the sliding
force. However, the increase in friction angle increases the friction coefficient.

1
TABLE OF CONTENTS
ABSTRACT...............................................................................................................................................1
1.0 INTRODUCTION AND THEORY....................................................................................................3
1.1 INTRODUCTION.............................................................................................................................3
2.0 EXPERIMENTAL PROCEDURE.....................................................................................................5
3.0 RESULTS AND ANALYSIS..............................................................................................................7
4.0 DISCUSSION.....................................................................................................................................11
5.0 CONCLUSION..................................................................................................................................13
6.0 RECOMMENDATIONS..................................................................................................................14
7.0 REFERENCES..................................................................................................................................15
8.0 APPENDICES....................................................................................................................................16

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1.0 INTRODUCTION AND THEORY
Tribology is the study of surfaces moving relative to one another, a phenomenon that affects our
lives in a multitude of ways every day (Hood, 2014). The term tribology is based on the Greek
word for rubbing and, although the term itself was not coined until 1964, there are images of
tribology in action from as long ago as ancient Egypt, when early tribologists used oil to help
facilitate sliding of large statues. Generally, tribology includes three key topics friction, wear and
lubrication. Friction is, by definition, the resistance to motion. The magnitude of this resistance is
a function of the materials, geometries and surface features of the bodies in contact, as well as
the operating conditions and environment. It is often desirable to minimize friction to order to
maximize the efficiency of a component or process. Friction increases with load and surface
roughness and can be decreased using a lubricant. While wear is the loss of material due to that
motion and lubrication is the use of a fluid to minimize friction and wear (Hutchings, 2011).The
field is necessarily interdisciplinary and utilizes skills from mechanical engineering, materials
science and engineering, chemistry and chemical engineering and more. Most mechanical
components have one or more moving parts. This means that something is moving relative to
something else, so there is tribology happening. In some components, such as bearings and gears,
the goal is to minimize the resistance to sliding or rolling so that as little energy as possible is
lost to friction. In other components, such as brakes and clutches, we want maximum sliding
resistance in order to limit the relative motions (Hutchings, 2011).
Tribology widely affects a vast majority of industries for example the manufacturing industry
has processes that rely on tribology, such as rolling, turning, stamping, grinding and polishing.
Further, most transportation methods depend on tribology, not only within the mechanical
components that drive them, but also at the contact between the wheels and the surfaces on
which they slide or roll. There are also examples of tribology in construction and exploration
equipment such as excavators, oil rigs, mine slurry pumps and tunnel digging drills. The
processes of friction and wear, and the use of lubricants to control friction and wear are
ubiquitous in a variety of industries.In addition to these applications of tribology, there are many
more devices and other products that we use regularly whose functions rely on tribology. They
include products and processes that arise in healthcare, sports, nature and more. In some cases
we want to maximum the friction such as on the soles of our shoes and in others we want to
minimize friction such as on the bottom of a bobsled (Hood, 2014). There are many examples of
tribology and tribology enabled function in the world of sports. For example, the bottoms of
athletic shoes are fine-tuned to provide just the right amount of resistance to sliding for a given
sport. Also, footballs and balls for other sports must be designed to be grip-able, but not too
sticky. There are many examples in sports equipment where tribology can be the difference
between winning or not. Common examples in winter sports include snow skis, bobsleds and
curling stones. There are also many natural processes where tribology is relevant. Some of these
processes occur on very large length scales. For example, earthquakes occur when friction builds
up over time until the earth cannot withstand the force and there is a shift (Aracil, 2021).
Tribology is particularly important in today's world because so much energy is lost to friction in
mechanical components. To use less energy, we need to minimize the amount that is wasted.

3
Significant energy is lost due to friction in sliding interfaces. Therefore, finding ways to
minimize friction and wear through new technologies in tribology is critical to a greener and
more sustainable world. Global energy consumption is expected to grow in upcoming years, and
the economic, environmental, and safety costs of wear induced failures can be extensive
(Macpherson, 2018). Moreover, many of the challenges facing new energy efficient technologies
such as wind turbines are tribological in nature. Therefore, tribology is critically important to
addressing some of the world's key issues related to energy efficiency and the economic and
societal implications of energy usage.
This lab experiment focused on proving friction between 2 bodies in contact and the adverse
effects of many different conditions on friction.
The coefficient of friction can be computed from:
μ=F Fric /F N
Equation 1

Where ;
F N =¿ The normal force

F Fric = The frictional force

This equation was used was used to obtain the coefficient of friction; this coefficient is a
measure of the amount of friction existing between two surfaces meaning that the greater the
coefficient of friction then the greater the friction between the 2 surfaces. These values usually
run from 0-1, but they can also be higher than one if the materials are especially sticky
(Macpherson, 2018). Essentially, if objects have a coefficient value of zero, there’s no friction.
This isn’t common, but it is possible with materials that have superfluidity. If materials have a
coefficient value of one, it means the friction force is the same as the normal force. In other
words, the force required to move the object is equal to that object's weight. Objects can also
have a friction value higher than one. For instance, rubber is a common material that can have a
particularly high coefficient of friction. As a general rule, most materials that aren’t wet tend to
fall in the 0.3-0.6 range.  Furthermore another frictional force that exists is the sliding force
which opposes the movement between two contact surfaces that slide against each other. This
force depends on the type of contact surfaces materials and finishing level and on the load
applied in the direction perpendicular to the motion direction normal force (Wang, 2021).
in mathematical terms, the sliding friction force is defined as follows:
F R =B r × N
Equation 2

where:
Br = sliding friction coefficient
N = normal force or load

4
If two bodies are initially stationary, the resistance force is called the static friction force
and represents the minimum force that must be applied to start moving the two bodies.
When the two bodies are in relative motion, a force lower than the static friction force
is sufficient to keep the speed constant: this is called the dynamic friction force (Hood,
2014). The friction coefficient is obtained experimentally for both static friction and dynamic
friction. There are different types of friction which are static, kinetic, deformation, molecular and
rolling. Each has its own coefficient of friction. Static coefficient Static friction is the force that
holds back a stationary object up to the point that it just starts moving. Thus, the static coefficient
of friction concerns the force restricting the movement of an object that is stationary on a
relatively smooth, hard surface (Jones, 2019).Kinetic coefficient Once you overcome static
friction, kinetic friction is the force holding back regular motion. This, kinetic fiction coefficient
of friction concerns the force restricting the movement of an object that is sliding on a relatively
smooth, hard surface.Deformation coefficient ,the deformation coefficient of friction concerns
the force restricting the movement of an object that is sliding or rolling and one or both surfaces
are relatively soft and deformed by the forces .Molecular coefficient , molecular coefficient of
friction concerns the force restricting the movement of an object that is sliding on an extremely
smooth surface or where a fluid is involved. Rolling coefficient ,the rolling coefficient of friction
combines static, deformation and molecular coefficients of friction. This coefficient of friction
can be made quite low (Giannocaro, 2017).There are certain laws that govern friction which
involve that the frictional force is always tangential to the contact surface and acts in the
direction opposite to that in which the body tends to move.The second law being that the
magnitude of frictional force is self-adjusting to the applied force till the limiting frictional force
is reached and at the limiting frictional force the body will have the impending motion.
Furthermore another law states that the limiting frictional force Fmax is directly proportional to
normal reaction Fmax = µsN). The fourth law states that for a body in motion, kinetic frictional
force Fk developed is less than that of limiting frictional force F max and the relation Fk = µkN is
applicable the frictional force also depends upon the roughness of the surface and the material in
contact and is independent of the area of contact between the two surfaces and the speed of the
body (Jones, 2019).

Moving on there different types of friction that are there which includes static friction which
acts on objects when they are resting on a surface for example, if you are hiking in the woods,
there is static friction between your shoes and the trail each time you put down your foot Without
this static friction, your feet would slip out from under you, making it difficult to walk which is
what , exactly what happens if you try to walk on ice (Hood, 2014). That's because ice is very
slippery and offers very little friction. Another type of friction is rolling friction which is friction
that acts on objects when they are rolling over a surface for example when maybe a soccer ball
rolls along the ground and then eventually comes to a stop because the rolling friction acts in the
opposite direction to the motion of the ball. Rolling friction is much weaker than sliding friction
or static friction. This explains why most forms of ground transportation use wheels, including
bicycles, cars, 4-wheelers, roller skates, scooters, and skateboards. Ball bearings are another use
of rolling friction. The third type of friction is fluid friction which is a type of friction that acts
on objects that are moving through a fluid. Afluid is a substance that can flow and take the shape
of its container. Fluids include liquids and gases. If you've ever tried to push your open hand
through the water in a tub or pool, then you've experienced fluid friction. You can feel
the resistance of the water against your hand (Hood, 2014).The vast applications of friction

5
include industries such as the transportation industry as well as in the household. In the
transportation industry automobile brakes rely on friction as it slows the vehicle when it converts
the kinetic energy to heat. Disk brakes also rely on it as well as drum brakes, brake shoes or pads.
Rail adhesion is the grip which a train’s wheel has on the rails. Moreover, an essential design and
safety factor for automobiles is road slipperiness. Split friction is a dangerous condition which
arises because of varying friction on either side of a car. While for the household friction also
helps in heating and igniting matchsticks. When the head of the matchstick rubs against the
surface of the matchbox, it produces fire. Further, we make use of sticky pads for preventing
objects from slipping off smooth surfaces as it efficiently increases the friction coefficient
between the object and the surface (Macpherson, 2018).

6
2.0 EXPERIMENTAL PROCEDURE

Figure 2.1 Showing the experimental set up

2.1 Friction Between Two Surfaces
For this experiment the equipment was set up as shown in figure 2.1 whereby the surfaces that
were used were cleaned for the experiment and the adjustable steel plane was positioned on a
firm bench so that the load on the hanger passes the edge of the bench as it descends. The plane
was clamped in the 0⁰ position and a spirit level was used to make sure the whole apparatus was
level. Thereafter all the slider blocks (including cord) and load hanger were recorded in a table.

 Friction Between Two Surfaces

Firstly, the aluminium block was placed on the horizontal steel channel at the end remote from
the pulley then the towing cord was attached and arranged over the pulley with the load hanger
suspended. After the hanger was ensured to not be swaying a load was added to the hanger until
the block continued to slide at a roughly constant velocity after being given a slight tap to induce
its motion. The load added was then recorded. You may find that you need to lightly tap the
bench which the unit is on or the apparatus itself to induce movement in the block. Also ensure
that the hanger is not swaying before loading. The same steps were repeated with four
increments of 1 N placed on top of the block and the results were recorded in a table. The above
procedure was repeated for the steel, brass and nylon blocks.

7
  Friction Coefficients on a Steel Surface

A 5N load was then placed on the aluminum block and weights were added gently to the load
hanger until the stationary block slider plus the 5N load suddenly moved at constant velocity.
The load was recorded as the static friction hanger load in a table. The initial procedure
explained previously for friction between 2 surfaces was repeated use (block still with 5N load),
the results were recorded in a table.
2.2 FRICTION ON AN INCLINED PLANE
The apparatus was set up as shown in figure 2.1 with the surfaces cleaned and the plane was
clamped in the 0⁰ position and a spirit level was used to make sure the whole apparatus was
level.

 Friction Angles on a Steel Plane

The aluminium block was placed in the middle of the steel plane and the pulley was held at the
end of the plane and the clamp was slackened so that the end could slowly be raised to tilt the
plane. As soon as the block started to slide the angle of inclination was noted and recorded in a
table. Thereafter, the tilt was reduced and the block was replaced to the middle. The tilt was then
increased and the block was slightly tapped until it kept moving, the angle was recorded as the
angle of inclination for sliding friction. The procedure was repeated for steel, brass and nylon
blocks.

 Nylon Friction Forces on an Inclined Steel Plane

The plane was clamped at 10⁰ inclination and the Nylon block was placed at the lower end with
the towing cord and load hanger in position to pull the block up the plane. Load was added to the
hanger until the block after being slightly given a push was able to slide slowly up the plane. The
procedure was repeated with a 5N weight on the top of the block. Results were recorded in a
table. The procedure above was repeated at angles of inclination 20⁰ ,30⁰ and 40⁰.

8
3.0 RESULTS AND ANALYSIS

Table 3.1 Showing the material, mass and weight

MATERIAL MASS (Kg) WEIGHT (N)

Load hanger 0.02 0.2
Aluminium / Steel 0.6975 6.84
Brass / Nylon 0.1953 1.92

SLIDING FORCE F (N) VS NORMAL FORCE (N)

3

2.5
SLIDING FORCE F (N)

1.5

0.5

0
6.84 7.84 8.84 9.84 10.84

NORMAL FORCE (N)

Aluminum Steel

Graph 3.1 showing the sliding force vs normal for aluminum on stainless steel and steel on
stainless steel

9
 FRICTION COEFFICIENT VS NORMAL FORCE (N)
0.3
FRICTION COEFFICIENT
0.25

0.2

0.15

0.1

0.05

0
6.84 7.84 8.84 9.84 10.84

NORMAL FORCE (N)

Aluminum Steel

Graph 3.2 showing the friction coefficient vs normal for aluminum on stainless steel and steel on
stainless steel

SLIDING FORCE F (N) VS NORMAL FORCE (N)

2.5
SLIDING FORCE F (N)

1.5

0.5

0
1.92 2.92 3.92 4.92 5.92

NORMAL FORCE (N)

Brass Nylon

Graph 3.3 showing the sliding force vs normal for brass on stainless steel and nylon on stainless
steel

10
 FRICTION COEFFICIENT VS NORMAL FORCE (N)
0.5
0.45
0.4
FRICTION COEFFICIENT

0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
1.92 2.92 3.92 4.92 5.92

NORMAL FORCE (N)

Brass Nylon

Graph 3.4 showing the friction coefficient vs normal for brass on stainless steel and steel on
stainless steel
Table 3.2 Showing slider, static friction and sliding friction for aluminum, steel, brass and nylon

SLIDER STATIC SLIDING

FRICTION FRICTION

Material Mass Hanger Total force Coefficient Hanger Total force Coefficient
(Kg) load (N) (N) load (N) (N)
Aluminium 0.6975 3.0 3.2 0.4678 2.8 3.0 0.4386

Steel 0.6975 4.6 4.8 0.7018 3.4 3.6 0.5263

Brass 0.1953 0.7 0.9 0.4688 0.6 0.8 0.4167

Nylon 0.1953 0.4 0.6 0.3125 0.3 0.5 0.2604

Total force = hanger load(N) + hanger (N)

3.0N +0.2N = 3.2 N
Coefficient = Total force (N)/ mass(kg)×9.81
3.2 N / 6.84N = 0.4678

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Table 3.3 Showing friction angles on steel plane

STATIC SLIDING
MATERIAL Angle (θ⁰) Coefficient Angle (θ⁰) Coefficient
(tan θ) (tan θ)
Aluminium 15.1 0.2698 13.2 0.2345
Steel 19.2 0.3482 13.5 0.2401
Brass 18.5 0.3350 17.3 0.3115
Nylon 16.5 0.2962 13.2 0.2345

Table 3.4 Showing Nylon Friction Forces on an Inclined Steel Plane

Angle of Weights Towing Weight Normal Sliding Friction Friction

plane added force of slide force force coefficient angle
θ (Kg) P W Wcos θ P-Wsin θ µ Tan-1µ
(N) (N) (N) (N) (⁰)
0 1.1 1.92 1.8908 0.7666 0.4054 22.07
10 0.5097 3.2 6.92 6.8149 1.9984 0.2932 16.34
0 1.3 1.92 1.8042 0.6433 0.3566 19.63
20 0.5097 4.1 6.92 6.5027 1.7332 0.2665 14.92
0 1.5 1.92 1.6628 0.5400 0.3248 17.99
30 0.5097 5.0 6.92 5.9929 1.5400 0.2570 14.41
0 1.8 1.92 1.4708 0.5658 0.3847 21.04
40 0.5097 5.8 6.92 5.3010 1.3519 0.2550 14.31
Weight of slide = weight of block + added weights
1.92N + 0 N= 1.92N
Normal force(N) = Wcos θ
1.92×cos 10= 1.8908
Sliding force(N) = P-Wsin θ
1.1- (1.92 × sin10) = 0.7666N
Friction coefficient = Sliding force(N) / Normal force (N)
0.7666N/ 1.8908N = 0.4054

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4.0 DISCUSSION
The aim of this experiment was to show that friction is proportional to the normal force as well
as to determine the coefficients of friction between various material when subjected to a plane
with an angle of 0⁰. Based on the results from graph 3.1 and 3.3 is it shown that as the normal
force for all the different materials increases then so does the sliding force which prompts the
observation that these two have a directly proportional relationship with each other. According to
(Hood, 2014) the force of friction always acts to oppose the force you apply when you try to
move an object hence friction is proportional to the force with which an object pushes against the
surface you’re trying to slide it along. The normal force is however the force pushing the two
surfaces together, and the stronger the normal force, the stronger the force due to friction. Steel
has the highest amount of sliding force than all the other materials which may be as a result of
the friction coefficient.
(Macpherson, 2018) explains that friction coefficient indicates the amount of interaction between
the two surface. It was observed during the experiment that when the nylon surface was
subjected to the stainless steel surface the nylon surface could easily slide against it hence based
on graphs 3.2 and 3.4 it can be seen that nylon has the lowest friction while steel has the highest
coefficient. A lower coefficient infers that the materials pass each other easily. These results
were conducive with a study conducted by (Wang, 2021) whose results showed that normally
then a material is rubbed against a piece of itself then there is always a high friction coefficient
which was observed by our steel against stainless steel results. (Giannocaro, 2017) however,
argues that ideally the friction coefficient should not change with the change in normal force as
when the normal force increases, the frictional force increases but your coefficient remains
unchanged. That is different than what was observed at during the experiment because in
practical sense the idealistic model fails 9 to 10 times (Macpherson, 2018). The sliding of two
surfaces causes heat and rise in temperature hence this can lead to second order effects.
Continued sliding can also polish the two surfaces reducing roughness and this can reduce the
coefficient. In other materials the sliding can create stickiness and lead to a slip-stick frictional
force that's unpredictable by any model except perhaps in a few cases by stochastic models as
such friction is in general nonlinear (Hutchings, 2011). This suggest that the coefficients of
friction were not independent of the normal force.
Based on the results from table 3.2 it is shown that the value of the sliding friction for all the test
blocks are lower than the static friction forces. This is because the inclined plane permits one to
overcome a large resistance by applying a small force through a longer distance than the load to
be raise. Static friction always has a higher value than sliding or kinetic friction due to the
amount of force used to overcome it. This correlates with the results obtained from this
experiment because the static friction value recorded for steel was 0.7018 while the sliding
friction value was 0.5263. (Hood, 2014) explains that the sliding friction is always less than the
static friction. This pattern is consistent throughout all the different block material (aluminum,
brass and nylon). (Wang, 2021) goes on to explain that static friction is the friction between two
surfaces that are not in relative motion with each other while sliding friction is the friction
between the surfaces in contact with each other and also sliding relatively to each other. The
force required to move static objects is far greater than those in motion. When comparing the

13
frictional coefficients from both parts of the experiment when the apparatus was placed at 0° the
coefficients were slightly less for all the material blocks that when the apparatus was set at
different angles or when the angle of friction was introduced which simply shows that the
inclined experiment is better that the horizontal experiment.
From the results in table 3.3 it is clearly shown that the friction angle and the friction coefficient
for static friction are higher than those of sliding friction. Angle of friction is always defined in
terms of motion on inclined plane. The minimum angle of incline for which a body placed on it
just starts sliding without any external force. When the body placed on some surface is just on
the point of sliding then in that condition the angle between applied force and normal force.
From table 3.4 the incline angles were varied between 10,20,30 and 40 degrees for an angle of 10
degree elevation the normal force was recorded to be 1.8908N while the sliding force was
recorded to be 0.766 and the coefficient of friction was recorded to be 0.4054 with the tangential
angel being 22.07. Comparing these findings to those that were recorded when a weight of
0.5097 was added there was a difference of 4.94 between the normal force recorded when there
was a weight of 0 and when there was a weight of 0.5097. Furthermore, a comparison between
the frictional coefficients recorded a difference 0.1122 was recorded which meant that for a
0.5097kg weight the frictional coefficient will be greater by 0.1122. The decrease in the
tangential angle from 22.07 degrees to 16.34 degrees was also noticed in the experimental data
which can lead to a reasonable conclusion being made as it is in line with what (Hutchings,
2011) obtained in a similar analysis and his review paper. A further review of the results
obtained when the angle of the plane was now shifted to 20 degrees showed that a friction
coefficient of 0.3566 and 0.2665 were recorded for a zero mass added and when a mass of
0.5097kg was added this showed a decrease in the frictional coefficient and the results obtained
were similar to those obtained by (Hutchings, 2011) in a similar research he did where obtained
a less frictional coefficient when he increased the incline angle , accounting this to the fact that ,
the increase in incline angle caused the sliding force to increase which in turn then also
decreased the frictional coefficient.

14
5.0 CONCLUSION
From the experimental data and results obtained various conclusions can be made. It can be
concluded that indeed friction and normal force have a proportional relationship. This was
successfully shown by the directly proportional relationship that was observed from the
experimental data as when there was a greater normal force acting on the blocks due to an
increased load then the sliding force was also observed to increase significantly. Clear evidence
of this relationship is displayed in the graph 3.1 which showed that when the normal force
increased at a steady rate the sliding force also increased steadily. Furthermore, it can be
concluded that the normal force which is the force that pushes surfaces against each other was
observed to increase when the friction coefficient increased which meant that the two surfaces in
contact were greatly opposing the movement of each other for a greater amount of normal force
and this suggested that there was much greater wear here as a greater frictional coefficient
signifies that interaction between surfaces in contact is now much greater. The experimental data
helps us make the conclusion that nylon has the lowest friction while steel has the highest
friction among all the materials meaning that nylon has much smoother surface than of steel.
This goes on to infer that there is less resistance or impedance to motion when the slide is in
contact with nylon than when it is in contact with steel. Another conclusion that can be made is
that the value of the sliding friction for all the test blocks is much lower than the static friction
forces hence the inclined plane permits one to overcome a large resistance by applying a small
force through a longer distance which leads to the conclusion that a greater sliding friction
results in a lower the static friction. We also concluded from the greater amounts of force which
was required to move static blocks compared to that required to those in motion that a greater
amount of force is required to move static objects as compared to moving those that are in
motion moreover the frictional coefficient is also higher for static friction that for sliding friction.
It can also be concluded that as the angle of friction is increased the friction coefficients as well
as both the normal force and sliding force are decreased. Lastly it is evident that when the
apparatus was placed at 0° the coefficients were slightly less for all the material blocks that when
the apparatus was set at different angles or when the angle of friction was introduced which
simply shows that the inclined experiment is better that the horizontal experiment.

15
6.0 RECOMMENDATIONS
The experiment can be improved by ensuring that the equipment used in the experiment is of
high quality and is also kept in good working condition which could be attained by regular
maintenance in order to reduce error or defects that may be as a result of equipment
malfunctioning. Secondly, the experiment could be repeated several times and the average results
can be calculated to make the results more accurate. The experiment can further be improved by
conducting the experiment at higher temperatures as well as lubricating the surfaces. One of the
other ways to improve the lab experiment is to induce vibration on the bench that the apparatus is
placed on to induce easy motion.

16
7.0 REFERENCES
Aracil, P., 2021. Eliminating Stuick Slip vibrations in drill strings with a dual loop control strategy, s.l.:
CRSO-SL algorithm.

Giannocaro, V., 2017. Identification of viscous friction coeficient for pneumatic system model using
optimization methods. Journal of mechanical simulaations , Issue 4, p. 34.

Hood, R., 2014. Optical sliding mode of surfaces in friction. Journal of physics , iii(53), p. 33.

Hutchings, K., 2011. Reduction of sliding friction of metals by the application of longitudinal and
transverse ultrasonic vibration. Journal of tribological research, Issue 3, p. 23.

Jones, S., 2019. REal time stick-slip and vibration detection for frictional surfaces. Journal of mechanical
engineering , iii(10), p. 27.

Macpherson, S., 2018. Fault free analysis of sracked gear based on analystical FE-method. Mech
Systems, ii(2), p. 78.

Wang, S., 2021. Numerical modelling on he;ical gears under progressive tooth waer for condition
monitoring , s.l.: s.n.

17
8.0 APPENDICES
Table 8.1 Showing normal force, sliding force and friction coefficient for aluminium on stainless
steel
Slide load (N) Normal force N Hanger load (N) Sliding force F Friction
(N) (hanger +hanger Coefficient
load) µ= F/N
( N)
0.00 6.84 0.9 1.1 0.1608

1.00 7.84 1.1 1.3 0.1658

2.00 8.84 1.3 1.5 0.1697

3.00 9.84 1.5 1.7 0.1728

4.00 10.84 1.7 1.9 0.1753

Table 8.2 Showing normal force, sliding force and friction coefficient for steel on stainless steel
Slide load (N) Normal force N Hanger load (N) Sliding force F Friction
(N) (hanger +hanger Coefficient
load) µ= F/N
(N)
0.00 6.84 1.3 1.5 0.2193

1.00 7.84 1.6 1.8 0.2296

2.00 8.84 1.9 2.1 0.2376

3.00 9.84 2.2 2.4 0.2439

4.00 10.84 2.5 2.7 0.2491

18
Table 8.3 Showing normal force, sliding force and friction coefficient for brass on stainless steel
Slide load (N) Normal force N Hanger load (N) Sliding force F Friction
(N) (hanger +hanger Coefficient
load) µ= F/N
0.00 1.92 0.7 0.9 0.4688

1.00 2.92 1.0 1.2 0.4110

2.00 3.92 1.3 1.5 0.3827

3.00 4.92 1.6 1.8 0.3659

4.00 5.92 1.9 2.1 0.3547

Table 8.4 Showing normal force, sliding force and friction coefficient for nylon on stainless steel
Slide load (N) Normal force N Hanger load (N) Sliding force F Friction
(N) (hanger +hanger Coefficient
load) µ= F/N
0.00 1.92 0.2 0.4 0.2083

1.00 2.92 0.4 0.6 0.2055

2.00 3.92 0.6 0.8 0.2041

3.00 4.92 0.8 1.0 0.2033

4.00 5.92 1.0 1.2 0.2027

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