index [] · 2018-02-28 · index sr. no. article name author page no 1 accelerometer based hand...

INDEX

Sr.

No. Article Name Author

Page

No

1 Accelerometer Based Hand Gesture

Controlled Robot K J Burle 1

2 DIMPLE JACKET G. M. Chendke 3

3 End effectors used in Robots Y.P.Ballal 5

4 3-D Electromagnetic Design And Analysis of an Eddy-Current Rail Brake System

P.D.Kulkarni 9

5 INVERTER AIR CONDITIONERS Jyoti S. Jadhav 12

6 Manufacturing Techniques of nano particles

and its applications A. D. Apte 15

7 Emerging Trends in Automotive Engineering R.V.Pethkar 22

8 VFA Welding For Joining High-Strength Metals

P. B. Patil 25

9 Development of the Nano Electronic Nose As

Gas Sensors A. M. Pirjade 27

10 Study of Powder mixed Electro Dicharge

Machining M. M. Salgar 29

11 Stunning Micro photos Capture Boozy

Beauty in Italian Cocktails G. B. Pawar 31

12 Hydrophobic and hydrophilic: How surfaces

attract or repel water P. M. Wadekar 33

13 Heat Transfer Enhancement Using Self-

rotating And Stationary Twisted Tape. A. R. Mane 36

14 Residual Stress G. N. Rakate 42

15 GYROSCOPIC PRECESSIONAL EFFECT

ON HELICOPTER A. A. Shinde 47

16 A Review on Natural Fiber Hemp as a

Composite Material S. A. Mullya 52

17 Personal Transport vehicle K. I. Nargatti 56

18 Nanotechnology H. H. Patil 58

19 Development of Thin Film Coating of CNT

for Tools used in EDM processes V. S. Ganachari 61

Vision of the Institute

To be a leader in producing professionally competent engineers

Mission of the Institute

We at ADCET, Ashta are committed to achieve our vision by

Imparting effective outcome based education

Preparing students through skill oriented courses to excel in their profession with

ethical values

Promoting research to benefit the society

Strengthening relationship with all stakeholders

Department Vision

To be a leader in developing mechanical engineering graduates with knowledge, skills &

ethics.

Department Mission

We, at the Department of Mechanical Engineering are committed to achieve our vision by,

M1- Imparting effective outcome based education.

M2- Preparing students to serve the society with professional skills and ethical values.

M3- Cultivating skills and attitude among students and faculties to promote research

Programme Educational Objectives (PEOs)

1. Provide solutions to the problems of mechanical and relevant engineering disciplines

using the knowledge of fundamental science and skills developed during graduation

studies.

2. Demonstrate an understanding about selected specific areas of mechanical

engineering in career development.

3. Communicate and function effectively using professional ethics, social and

environmental awareness.

4. Engage in lifelong learning, for effective adaptation to technological changes.

Program Outcomes (POs):

Students of Mechanical Engineering Graduates will be able to:

1. Engineering knowledge: Apply the knowledge of mathematics, science, engineering

fundamentals, and an engineering specialization to the solution of complex engineering

problems.

2. Problem analysis: Identify, formulate, review research literature, and analyze complex

engineering problems reaching substantiated conclusions using first principles of mathematics, natural sciences, and engineering sciences.

3. Design/development of solutions: Design solutions for complex engineering problems

and design system components or processes that meet the specified needs with appropriate consideration for the public health and safety, and the cultural, societal, and environmental

considerations.

4. Conduct investigations of complex problems: Use research-based knowledge and

research methods including design of experiments, analysis and interpretation of data, and

synthesis of the information to provide valid conclusions.

5. Modern tool usage: Create, select, and apply appropriate techniques, resources, and

modern engineering and IT tools including prediction and modeling to complex engineering

activities with an understanding of the limitations.

6. The engineer and society: Demonstrate understanding of contemporary knowledge of

engineering to assess societal, health, safety, legal and cultural issues and the consequent

responsibilities.

7. Environment and sustainability: Understand the impact of the professional engineering solutions in societal and environmental contexts, and demonstrate the knowledge of, and

need for sustainable development.

8. Ethics: Apply ethical principles and commit to professional ethics and responsibilities and norms of the engineering practice.

9. Individual and team work: Function effectively as an individual, and as a member or

leader in diverse teams, and in multidisciplinary settings.

10. Communication: Communicate effectively on complex engineering activities, write

effective reports, make effective presentations, and give and receive clear instructions.

11. Project management and finance: Demonstrate knowledge and understanding of the

engineering and management principles and apply these to manage projects and in

multidisciplinary environments.

12. Life-long learning: Recognize the need for, and have the ability to engage in

independent and life-long learning in the broadest context of technological change.

PSO1. An ability to find out, articulate the local industrial problems and solve with the use

of mechanical engineering tools for realistic outcomes.

PSO2. An ability of collaborative learning to find out cost-effective, optimal solution for

social problems

Influence December 2016

Department of Mechanical Engineering 1

1. Accelerometer Based Hand Gesture Controlled Robot

K J Burle

Asst. Professor

In many application of controlling robotic gadget it becomes quite hard and

complicated when there comes the part of controlling it with remote or many different

switches; mostly in military application, industrial robotics, construction vehicles in civil

side, medical application for surgery. In these fields it is quite complicated to control the

robot or particular machine with remote or switches, sometime the operator may get

confused in the switches and button it, so a new concept is introduced to control the

machine with the movement of hand which will simultaneously control the movement of

robot. A Gesture Controlled robot is a kind of robot which can be controlled by your hand

gestures not by buttons. Operator just need to wear a small transmitting device in hand

which includes an accelerometer. This will transmit an appropriate command to the robot

so that it can do whatever it is supposed to. The transmitting device includes an ADC

for analog to digital conversion and an encoder which is used to encode the four bit data

and then it will transmit by an RF Transmitter module. At the receiving end an RF

Receiver module receives the encoded data and decodes it by decoder. This data is then

processed by a microcontroller and finally motor driver to control the motors.

This wok will be divided into two different parts

1) Transmitter and

2) Receiver.

We will discuss both of them one by one.

Accelerometer:

An Accelerometer is a sensor which gives an analog data while moving in X,Y,Z

direction or may be X,Y direction depending on the type of the sensor.

Here is a small image of an Accelerometer shown. We can see in the image that their are

some arrow showing if we tilt these sensor's in that direction then the data at that

corresponding pin will change in the analog form.


Department of Mechanical Engineer ing 2

Transmitter Block Diagram

Receiver Block Diagram

Application

1. Military application to control robotics

2. Medical application for surgery purpose.

3. Construction application.

4. Industrial application for trolly control, lift control, etc.

References:

[1]http://www.engineersgarage.com/contribution/accelerometer-based-hand-

gesture-controlled-robot?page=1

[2]http://circuitdigest.com/microcontroller-projects/accelerometer-based-hand-

gesture-controlled-robot-using-arduino

[3] SwarnaPrabha Jena, Sworaj Kumar,“Accelerometer Based Gesture Controlled Robot

Using Arduino”, International Journal Of Engineering Sciences & Research

Technology, Apr.2015

http://www.engineersgarage.com/contribution/accelerometer-based-hand-

http://circuitdigest.com/microcontroller-projects/accelerometer-based-hand-


2. DIMPLE JACKET

G. M. Chendke

Asst. Professor

Dimple Jacket or Jacketed vessel is a container that is designed for controlling the

temperature of container, by using a cooling or heating the jacket, which is placed

surrounding the container through which a cooling or heating fluid is circulated

A dimple jacket is containing the cavity which allows the uniform exchange of

heat between the fluid circulating in it and the walls of the vessel.[1][2]. (Fig.1& 2).The

pharmaceutical, biotech, food, dairy and beverage industries which are having high purity

applications use these dimple jacket heat exchangerswhich are made up of type 304 and

mainly 316L stainless steel [3].

The embossed dimple jacket attached to the outside wall of the vessel keeps the

container hot or cooled. From the dimple jacket,steam, cooling water or other media is

passed from passage created by interconnecting the channels formed by network of

dimples. The design typically involves a thin sheet of stainless steel shaped to create a

network of dimples which are welded to the much thicker vessel wall. Because of the

thermal stresses and strains formed during rapid heating and cooling, corrosive

conditions, 316L dimple jackets are susceptible to premature failures.There are several

types of jackets, depending on the design.[3]

Fig. 1: Dimple Jacket detail [3] Fig. 2: Dimple Jacket Tank [4]



Advantages of Dimpled Jacket Over Plain Jacket:

1) Heat flows rapidly from the outer surface to inner surface through the welds (contact

area of Dimpled Jacket with Tank wall) and hence the heat transfer increases.

2) Overall heat transfer coefficient ‘U’ is significantly higher.[5]

A high value of U leads to lower area of heat transfer and hence less wall

resistance. There is considerable reduction in the thickness of Tank/Vessel wall which is

desirable for , both for heat transfer and weight reduction,&which will lead to significant

money savings.[5]

The dimpled jacket can be made up of thinner wall because it is based on using a

relatively short distance between the dimples. Even though, there are large number of

reinforcing dimples, the thickness of both, the inner and outer walls can be considerably

reduced.[5]

In process point of view, following design parameters are affected by use of a

thinner shell and the turbulence created in the jacket side-

Dimple size and shape.

Diameter of weld (i.e., contact area)

Dimple arrangement (i.e. pitch)

Jacket space or jacket volume.

Dimple density.[5]

Dimpled jacket are preferred in many areas because of its performance , less wall

thickness, more heat transfer rate & many more.[5]

References:

1. http://www.cheresources.com/content/articles/heat-transfer/jacketed-vessel-

design?pg=3

2. https://en.wikipedia.org/wiki/Jacketed_vessel

3. Outokumpu-corrosion-management-news-Acom-1-edition-2007.pdf

4. http://www.watcopumps.com/watcotanks/p34_t.html

5. http://www.highlandequip.com/download/DimpledJacket2.pdf

http://www.cheresources.com/content/articles/heat-transfer/jacketed-vessel-

https://en.wikipedia.org/wiki/Jacketed_vessel

http://www.watcopumps.com/watcotanks/p34_t.html

http://www.highlandequip.com/download/DimpledJacket2.pdf



3. End effectors used in Robots

Y.P.Ballal

Asst. Professor

I. INTRODUCTION

End effectors are a device that is attached to the wrist of robot arm so as to enable the robot

to perform a specific task. It is some time referred as the hand of the robot. In robotics, end

effectors are the device at the end of a robotic arm, designed to interact with the

environment. The exact nature of this device depends on the application of the robot. In

the strict definition, which originates from serial robotic manipulators, the end effectors

means the last link (or end) of the robot. At this endpoint the tools are attached. In a

wider sense, end effectors can be seen as the part of a robot that interacts with the work

environment. This does not refer to the wheels of a mobile robot or the feet of a

humanoid robot which are also not end effectors—they are part of the robot's

mobility. [1]

The two major categories of end effectors are: 1. Grippers 2. Tools

Grippers are end effectors used to graph and hold objects. The objects are generally

work parts that are to be moved by robot, Grippers can be classified as single

grippers or double grippers. This classification applies best to mechanical grippers.

Single grippers is distinguished by the fact that only one grasping device is mounted

on robot’s wrist. A double gripper has two gripping devices attached to the wrist and is

used to handle two separate objects. The two gripping devices can be actuated is especially

useful in machine loading and unloading applications. The term multiple grippers is

applied in the case where two or more grasping mechanisms are fastened to the wrist.

Another way of classifying grippers depends on whether the past is grasped on its

exterior surface as its internal surface, e.g. a ring shaped part. The first type is called an

external gripper and second type is called internal grippers.

II. MECHANICAL GRIPPERS

We can think of a mechanical gripper as a robot hand. A basic robot hand will have

only two or three fingers A mechanical hand that wraps around an object will rely on

friction in order to secure the object it is holding. Friction between the gripper and the

object will depend on two things, First is the type of surface whether it be metal on

metal, rubber on metal, smooth surfaces or rough surfaces and the second is the force



which is pressing the surfaces together. Mechanical grippers are often fitted with some type

of pad usually made from polyurethane as this provides greater friction. Pads are less

likely to damage the work piece. Pads are also used so to have a better grip as the

polyurethane will make contact with all parts of the surface when the gripper is

closed. Mechanical grippers can be designed and made for specific purposes and

adjusted according to the size of the object. They can also have dual grippers. We are

all familiar with the saying ‘two hands are better than one” and robots benefit from

having dual grippers as they can increase productivity, be used with machines that have

two work stations where one robot can load two parts in a single operation, operations

in which the size of objects or part change due to the machining processes and where the

cycle time of the robot is too slow to keep up with the production of other machines.

[2]

III. OTHER TYPES OF GRIPPERS

A. Vaccum Cups

They are also called suction cups.The usual requirements on the objects to be handled

are that they be flat, smooth and clean conditions necessary to form a satisfactory

vacuum between object and suction cup. Suction pads some in a wide range of material

to meet specific application requirements.E.g. nitrile, silicone,natural rubbers,

fluoroelastomers, polyurethanes.The co-efficient of friction between work piece and

suction pad is very important.[3]

Oily surfaces : μ = 0.1

Moist or wet surfaces : μ = 0.2 to 0.4

Glass, stone, plastic (dry) : μ = 0.5

Wood and metal : μ = 0.5

Rough surface : μ = 0.6

Sandpaper (dry) : μ =01.1

B. Magnetic Grippers

Magnetic grippers obviously only work on magnetic objects and therefore are

limited in working with certain metals. For maximum effect the magnet needs to have

complete contact with the surface of the metal to be gripped. Any air gaps will reduce

the strength of the magnetic force; therefore flat sheets of metal are best suited to

magnetic grippers. If the magnet is strong enough, a magnetic gripper can pick up an

irregular shaped object. In some cases the shape of the magnet matches the shape of the



object A disadvantage of using magnetic grippers is the temperature. Permanent

magnets tend to become demagnetized when heated and so there is the danger that

prolonged contact with a hot work piece will weaken them to the point where they can

no longer be used. The effect of heat will depend on the time the magnet spends in

contact with the hot part. Most magnetic materials are relatively unaffected by

temperatures up to around 100 degrees. Electromagnets can be used instead and are

operated by a DC electric current and lose nearly all of their magnetism when the

power is turned off Permanent magnets are also used in situations where there is an

explosive atmosphere and sparks from electrical equipment would cause a hazard.

C. Adhesive Grippers

Gripper designs in which an adhesive substance performs the grasping action can be

used to handle fabrics and other light weight materials, Adhesive material is loaded in the

form a continuous ribbon into a feeding mechanism that is attached to the robot wrist.

D. Hooks, Scoops

Hooks and scoops are the simplest type of end effectors that can be classes as grippers.

A scoop or ladle is commonly used to scoop up molten metal and transfer it to the

mould. Tools as End Effectors

1. Welding

2. Painting

3. Drilling, Flaming, Tapping

4. Riveting

Welding: Welding gun is used as end effectors. Welding process in which robot is used

is of two types.

1. Spot Welding

2. Continuous Arc Welding

Spot welding: The process of welding in which two similar metal pieces are localized

heated by passing a large current through the parts are to be welded. These current

results sufficient heat the contact area to fuse the two metals and produce the weld. A

end effectors to robot’s wrist and the robot is programmed to perform a sequence of

welds on the product as it arrives at the workstation. Some robot spot welding

lines operate with several dozen robots programmed to perform different welding

cycles on the product. The product quality is improved and production rate is high.

Continuous Arc welding : Continuous arc welding is used to made long welded

joints in which an air tight seal is often required between the two pieces are being



joined. Here welding electrode gun is used for making long continuous welding joints

in an in here protective gates atmosphere to preserve the quality of weld.

Sequences of steps to be performed are fed in the control unit of robot and its works

in the same manners. To guide the welding gun and check the quality of welding done

by robot a vision based system is used. A high vision camera is mounted on the robot

near the welding gun to view the path and compare the quality of welt made as

programmed. Robovision II from Automatic Inc. and west vision from General

Electric are examples of commercial vision system in a single pass category. In the

automatic system the camera is focused about 4 cm in front of weld. The observed

image is analyzed to extract the location of the entire of seam etc.

Painting

The commercial industrial painting method are categorized as follows: -

1. Immersion and flow coating method 2. Spray - Coating method.

Immersion and flow coating method - The object is completely dipped in primmer

solution. The primmer solution bath is a electrically charged positive and it gets

stick to the object. After keeping it for some time the object is removed and died in a

furnace for about 2-4 hrs at temp from 200c to 100 c. After the baking of object it

comes into atmosphere. All these activities are tone by one or more than one robotic

manipulator arm as per the size of object. Then, object is again dipped in liquid paint

for some time. As the paint is electrically charged positive it gets tick on the

object. After keeping it for some time object gets removed from the bath of paint and

again kept in furnace for 1-2 hrs at a temp.100C to 200 C. So that paint may get tried

up. The body / object is quietly inspected for any leftover marks and after satisfying all

requirements buffing and polishing of the object take place. Besides visual inspection

robotic inspection is also performed and results get verified with each other. [4]

References

[1] A.J. Weight, “Light Assembly Photos - An End Effectors Exchange Mechanisms”

Mechanical Engineering, July 1983 PP 29-35

[2] Michanel Tucker “Generalized Inverses For Kobotic Manipulator’s” Mech.

Machine Theory, Volume 22, No 6 PP 507-514 1981.

[3] Steve Prehn, “Robots / Automation, Machine Design Magazine” December 8, 2011 PP

46,48.

[4] G.L. Luntstrorm, B Glenme, and B.W, Rocbs Industries “Robots Gripper Review”,

International Fluidics services Ltd., Bedford, England



4. 3-D Electromagnetic Design And Analysis of an Eddy-Current

Rail Brake System

P.D.Kulkarni

Asst. Professor

Recently, the demand for high velocity railway systems has increased and several new

vehicles have been developed. To make high-speed railways a reality, a new brake system

that supplements the conventional brake system is required.

The eddy-current rail brake system has therefore been developed as an emergency

brake mainly by the East Japan Railway Company, Railway Technical Research Institute

and Toshiba.

Fig l. shows the principle of the rail brake system, Under the bogie, armature coils are

arranged in the longitudinal direction of the rail so that N- and S-poles are alternately

inline. On deceleration of the vehicle, the armature coils are excited and eddy currents are

induced in the rails by the relative movement of the rails and the coil fields. The eddy

currents exert a drag force, which acts as a brake force.

Furthermore, as the brake shoes on top of the poles are pulled against the rails by

magnetic attraction, the friction force between the shoes and the rails acts as a brake. The

rail brake described in this paper m&es use of both the friction force caused by magnetic

attraction and the drag force caused by eddy currents. In order to optimize the design of

the brake system, it is necessary to estimate the braking force and the distribution of

magnetic flux and eddy current. But because of eddy currents by the movement and non-

linearity of the magnetic materials, only analytical method or numerical method with

simplified model has been applied to this type of problem From the point of determining



the design parameters of the practical rail brake system, this paper presents a new method

of estimating the braking force of a rail brake system using a 3D FEM considering both

eddy currents and non-linearity of the magnetic materials, evaluates the validity of the

method comparing with the measurements and also describes the results of the optimum

design of the practical brake system.

ANALYSIS METHOD AND MODEL

For the analysis of the rail brake, it is important to 0 Relative movement of the brake and

the rail * Magnetic saturation of the poles, the shoes and the rails 0 Three-dimensional

configuration of the poles. However, the following problems are involved when trying to

take all these into account:

1) Such that it is difficult to calculate electromagnetic field stably and precisely.

2) The required analysis meshes become very small, hence the dimension of the problem

becomes too large to solve using conventional workstations. 0 The calculation requires

iteration for both the velocity term and saturation effect, and thus takes too long.

Therefore, we have developed a new analysis method. First, an FEM model of the

rail brake and the rail is constructed. AC current with the frequency corresponding to the

running velocity is supplied to the coil. The amplitude of the current is the DC current

value supplied in practice and the phase differs by 180 degrees with the neighboring pole.

Fig2 shows an example of the FEM model of the rail brake used in the analysis. This rail

brake has 6 poles per single brake and 114 of the brake is displayed as it is symmetrical in

2 planes. In this model, an air gap between the brake shoes and the rail is set to avoid

multiple connections. Unknowns are magnetic vector potential and electric scalar

potential and the Newton-Raphson method is used in the nonlinear calculation.

In this method, the fundamental component of the space harmonics is modeled

precisely. Because the skin depth is mainly due to the fundamental component, magnetic

resistance of the analysis region is expressed accurately.



Fig3 shows the magnetic flux distribution of the brake and the rail. As the polarity of the

magnetic poles is arranged alternately, flux loops are induced with the adjacent poles. As

for the rail, most of magnetic flux flows in the head of it. The poles and the surface of the

rail are almost saturated and the average relative permeability of the surface of the rail

just under the pole is about 40. Fig.4 shows the friction, the eddy-current and the total

bralung force versus the running velocity of the vehicle.Measurements are acquired from

the experiments on a test bench. The test bench is composed of roundly-arranged poles

and the simulating rail around the circumference of ,the circle plate. As shown in the

figure, the velocity characteristics of the braking force agree closely with the

measurements. This indicates that the principle of the analysis method is applicable. The

difference of the eddycurrent braking force is aibout 30% and that of the total braking

force is within 10-20%..

References :

1. N. Takahahi, S. Kawai, K. Akai, IEEYvo1.90,No.2 pp.129-138,1970 D.Rodger,

T.Karagular, P.J.Leonard, “A formulation for 3D moving conductor eddy current

prodlems”, IEEE Trans. Mugn., vol. 25, No. 5, pp.4147-4149, September l?S9

2. D.Alhertz, S.Dappen, G.Hermeherger, “Calculation of the 3D non-linear eddy

current field in moving conductors and its application to braking systems”, IEEE

Truns. Mug+, vol. 32, No. 3. pp.768-771, May 1996 N.Esposito,

3. A.Musolino, MRaugi, “Modelling of three-dimensional nonlinear eddy current

prdhlems with conductors in motion by anintegral formulation”, IEEE, Truns.

Mugn., vol. 32, No. 3, pp.764-767, May 1996



5. INVERTER AIR CONDITIONERS

Jyoti S. Jadhav

Asst. Professor

Inverter AC vs normal AC

The best type of AC to buy is an inverter AC, which not only saves electric power cost,

but is more silent and comfortable with steady continuous cooling.

A normal AC first over cools the room and cuts off the compressor till the room again

gets warm, then it will restart. This constant starting and stopping of normal AC

compressor makes the room too cold for a short while and then it becomes too warm.

This does not lead to a comfortable sleep. Also with the AC compressor running at high

speeds when it is on, and with the constant restart of the AC compressor, a normal AC

consumes a lot of current making a normal AC very inefficient and costly to use.

An inverter AC on the other hand controls the temperature of the room by running the

compressor at different speeds, at very slow speed when the room is at the right

temperature and speeds up if the temperature starts going up. Thus a room cooled by an

inverter AC stays at a constant comfortable temperature enabling a very good sleep.

Compared, inverter AC vs normal AC, an inverter AC uses 40% less electric power and

you get a much better sleep with constant cool temperature. The inverter AC is very silent

and lasts much longer than normal AC, because the inverter AC runs at slower speeds and

there is no wear and tear of the compressor stopping and starting constantly.

How inverter AC works:

In an inverter AC, the 50 cycles per second or 50Hz alternating current in our power

supply is first converted into a Direct Current DC and then it is reconverted into an

alternating current where the frequency is infinitely variable, from say 10 cycles per

second or HZ to say 100 cycles per second. This variable frequency enables the main

compressor motor of the AC to turn at different speeds. With the fixed 50Hz AC of our

electric supply, the compressor motor of normal air conditioner can only turn at one

speed, but with a variable frequency, the compressor motor of the AC can run at different

speeds, from very low to very high speeds. There are many advantages of the AC

compressor to be run at different speeds as explained below.

The problem with the fixed 50Hz power supply is that it will turn electric motors only at a

fixed speed depending on the number of poles. Since the speed of any electric motor

depends on the frequency of the voltage applied to it, so to control the speed of an electric

motor, the most efficient way is to control the frequency of the power supply voltage. To



achieve this, the AC power supply to our houses has to be first converted into DC and this

DC power converted back to AC voltage with the ability to infinitely control the

frequency of the AC voltage. The device that converts DC voltage to AC voltage is

known as an inverter.

A 5 star normal AC is the most efficient normal AC, but it cannot be as efficient as an

inverter AC, because the inverter AC works on a totally different principle. Also inverter

ACs have no star rating as yet in India.

The regular AC compressor has only one speed and the cooling is controlled by offing the

AC compressor when a set cold temperature has been reached and then restarting the AC

compressor when the room heats up and reaches a set temperature. For example, if you

set the thermostat in the regular AC to cool the room to 22 degrees, then the AC

compressor starts when the room temperature is 24 degrees and stops when the room has

cooled to 20 degrees. This is the cycle that repeats itself throughout the period that the

AC is on. This is a very inefficient way of the compressor working. The problems with

this arrangement are as follows:

1. When a compressor is running at its full speed it is very inefficient. The relation

between efficiency and speed is that efficiency varies inversely as the square of

the speed. To put it simply, if the speed is double then the efficiency reduces by a

factor of the square of the speed, that is, efficiency reduces by 4 times. So, the

slower the compressor runs, the more efficient it is.

2. Start up current in any motor is very high. When a normal AC is on, the

compressor starts and stops several times, minutes apart. This start stop cycle

consumes a lot of power and is very inefficient.

3. The temperature in the room is not a constant comfortable level. It is varying

between a minimum and maximum temperature of several degrees apart, and the

room is constantly changing from uncomfortably cold to uncomfortably hot, with

the set comfort temperature zone in the middle of these uncomfortable

temperature range.

Benefits of inverter AC compared to normal AC

An inverter compressor in AC solves all the disadvantages of the normal AC and saves

more than 40% on electricity bills as claimed by some of the manufacturers. Apart from

this the inverter AC is very silent compared to a normal AC and the compressor lasts

much longer, because it is never stressed.



When an inverter AC is put on, the compressor starts slowly and picks up speed gradually

and reaches a higher speed than a normal AC for a short period to cool the room faster

than a normal AC. Once the set temperature of say 22 degrees C is reached, the

compressor slows down and has just enough speed to maintain the set temperature of the

room. The compressor never stops while the AC is on; it just runs very slowly cooling the

room just enough to maintain the set temperature. The variance in temperature in the

room will be in decimals, in our example of 22 degrees it may go down to 21.9 and up to

22.1 degrees, which is negligible.

Apart from these advantages we can have a much more silent AC. The room temperature

with an inverter AC will be always comfortable without the room becoming too cold for

some time and then becoming too warm like with a normal AC.



6. Manufacturing Techniques of nano particles and its

applications

A. D. Apte

Asst. Professor

SOL GEL TECHNIQUE

Sol gel technique which is one of the oldest methods of crystal growth is defined as a

wet-chemical technique widely used in the fields of materials science and ceramic

engineering. Sol-gel technique is a simple and cost effective method to produce ceramic

powders. It is used primarily for the fabrication of materials starting from a colloidal

solution (sol) that acts as the precursor for an integrated network or gel of either discrete

particles or network polymers. It makes use of cheap and available materials. It can be

used in ceramics processing and manufacturing as an investment casting material, or as a

means of producing very thin films of metal oxides for various purposes.

The methods of crystal growth can generally be grouped into two, thus; Vapour Phased

Deposition which includes, Evaporation, Molecular Beam Epitaxy (MBE), Sputtering,

Chemical Vapour Deposition(CVD) and Atomic Layer Deposition (ALD) and Liquid

Based Growth which includes Chemical Solution Deposition, Electrochemical

Deposition, Chemical Bath Deposition(CBD)

METHODS OF GEL PRODUCTION

There are four methods for the production of gels-

(i) Flocculation of lyophilic- colloids by salts or precipitating liquids.

(ii) Evaporation of certain colloidal solutions

(iii) Chemical reactions that lead to change in shape of lyophilic molecules (e.g. the

denaturation of albumen on heating involves some uncoiling of the protein

molecules and a gel structure results).

(iv) Swelling of a dry colloid (xerogel) when placed in contact with a suitable liquid

(e.g. starch granules added to water).

The presence of a network formed by the interlocking of particles of the gelling agent

gives rise to the rigidity of a gel. The nature of the particles and the type of form that is

responsible for the linkages determine the structure of the network and the property of the

gel. Aerogels are sol-gel derived solid materials with porosities from about 80-98%.

The high porosity is achieved through supercritical drying of wet gel in an autoclave



Applications of sol gel

1. Protective coatings

The applications for sol gel-derived products are numerous . For example, scientists have

used it to produce the world’s lightest materials and also some of its toughest ceramics.

One of the largest application areas is thin films, which can be produced on a piece of

substrate by spin coating or dip coating. Protective and decorative coatings and electro-

optic components can be applied to glass, metal and other types of substrates with these

methods. Cast into a mold, and with further drying and heat-treatment, dense ceramic or

glass articles with novel properties can be formed that cannot be created by any other

method. Other coating methods include spraying, electrophoresis, inkjet printing or roll

coating.

2. Thin films and fibers

If the viscosity of a sol is adjusted into a proper range, both optical and refractory ceramic

fibers can be drawn which can be used for fiber optic sensors and thermal insulation,

respectively. Many ceramic materials, both glassy and crystalline, have found use in

various forms from bulk solid-state components to high surface area forms such as thin

films, coatings and fibers.

3. Nanoscale powders

In the process of precipitation, ultra-fine and uniform ceramic powders can be formed

which are powders of single and multiple component compositions of nanoscale particle

size for dental and biomedical applications. Composite powders have been patented for

use as agrochemicals and herbicides. Powder abrasives, used in a variety of finishing

operations, are made using a sol-gel type process. One of the more important applications

of sol-gel processing is to carry out zeolite synthesis. Other elements (metals, metal

oxides) can be easily incorporated into the final product and the silicate sol formed by this

method is very stable.

Sol gel is applied in research to entrap biomolecules for sensory (biosensors) or catalytic

purposes, by physically or chemically preventing them from leaching out and, in the case

of protein or chemically-linked small molecules, by shielding them from the external

environment yet allowing small molecules to be monitored. The major disadvantages are

that the change in local environment may alter the functionality of the protein or small

molecule entrapped and that the synthesis step may damage the protein. To avoid this,



various strategies have been explored, such as monomers with protein friendly groups

(e.g. glycerol) and the inclusion of polymers which stabilize protein.

Other products fabricated with this process include various ceramic membranes for

microfiltration, ultrafiltration, nanofiltration, pervaporation and reverse osmosis. When

the liquid in a wet gel is removed under a supercritical condition, a highly porous and

extremely low density material called aerogel is obtained. On drying the gel by means of

low temperature treatments (25-100 °C), it is possible to obtain porous solid matrices

called xerogels. In 1950s, a sol-gel process was developed for the production of

radioactive powders of UO2 and ThO2 for nuclear fuels, without generation of large

quantities of dust.

4. Opto-mechanical

Sol gel route can be used to make macroscopic optical elements and active optical

components as well as large area hot mirrors, cold mirrors, lenses and beam splitters all

with optimal geometry at low cost. In the processing of high performance ceramic

nanomaterials with superior opto-mechanical properties under adverse conditions, the size

of the crystalline grains is determined largely by the size of the crystalline particles

present in the raw material during the synthesis or formation of the object. Thus a

reduction of the original particle size well below the wavelength of visible light (~ 0.5 μm

or 500 nm) eliminates much of the light scattering, resulting in a translucent or even

transparent material.

Also, results indicated that microscopic pores in sintered ceramic nanomaterials, mainly

trapped at the junctions of microcrystalline grains, cause light to scatter and prevented

true transparency. It was also observed that the total volume fraction of these nanoscale

pores (both intergranular and intragranular porosity) must be less than 1%

CHEMICAL VAPOR DEPOSITION

In a chemical vapor deposition (CVD) process, a thin film of some material is deposited

onto a surface via the chemical reactions of gaseous molecules that contain the atoms

needed for the film material. These chemical reactions take place on the surface and in

many cases also in the gas phase. To fully understand the chemistry in the process and

thereby also have the best starting point for optimizing the process, theoretical chemical

modeling is an invaluable tool for providing atomic-scale detail on surface and gas phase

chemistry. This overview briefly introduces to the non-expert the main concepts, history

and application of CVD, including the pulsed CVD variant known as atomic layer



deposition (ALD), and put into perspective the use of theoretical chemistry in modeling

these processes.

Thin films are layers of materials with thicknesses ranging from less than one nanometer

(a few atomic layers) to hundreds of micrometers (for reference, a human hair is about 75

μm thick) . The importance of thin films in today’s society is enormous and thin films can

be found everywhere; from low friction coatings in a car engine to the anti-reflecting

coating on the lenses of spectacles, as well as the decorative coating on their frames. Most

metal objects around us have been machined by cutting tools that are coated with a hard,

wear-resistant thin film. Replacement parts for the human body, such as hip-joints, are

often coated with a thin film to make them more bio-compatible. Furthermore, today’s

nanoelectronic devices are built up very precisely from stacks of thin films of various

materials with different electrical properties, with some of the films as thin as one atomic

layer. Technologically important thin films can be amorphous, polycrystalline or

epitaxially-grown single crystals and the properties of the materials can often be tuned

with great precision to suit various applications.

To coat an object (the “substrate”) with a thin film, it is often preferred to start from

atoms or molecules in a vapor phase and place the object(s) to be coated in that vapor,

letting atoms and/or molecules from the vapor build up a thin film on the surface of the

object. These vapor-based thin film synthesis methods are classified as either physical

vapor deposition (PVD) or chemical vapor deposition (CVD), depending on whether the

film deposition process is driven by physical impacts or by chemical reactions,

respectively. Generating the vapor in the reactor is of course straightforward when the

desired element is available in gaseous form, e.g. O2, but this is not the case for most

elements. Therefore, in PVD, a solid sample containing the target elements is subjected to

substantial energy, often in the form of a plasma or an electric discharge, thereby ejecting

atoms and producing a vapor, which can then condense onto the substrate . In CVD,

target elements are delivered in the form of volatile molecules, denoted as precursors, and

the film is built up via a series of chemical reactions between precursors, precursor

fragments and the substrate. In the general case, such 4 reactions can take place both in

the gas phase and on the substrate surface. However, a form of CVD named atomic layer

deposition (ALD) uses only surface chemical reactions to build up thin films with great

precision.

The precursor molecules are often diluted in a carrier gas that makes up the main part of

the gas volume in the process, analogous to the solvent in liquid-phase chemical



reactions. The carrier gas in CVD is most often hydrogen, nitrogen or argon, or mixtures

of these. The majority of CVD processes are thermally activated by applying

temperatures typically in the range 200-2000°C, although there are examples of CVD and

ALD processes at lower temperatures, even down to room temperature, and at higher

temperatures up to 2500°C. There are also CVD and ALD processes that use a plasma to

activate the chemistry by opening up new reaction pathways, by electron impact

collisions and by the generation of ions and radicals, and these processes are referred to as

Plasma Enhanced CVD (PECVD) or alternatively Plasma Assisted CVD (PACVD). The

gas phase chemistry can also be activated by photons from a laser, referred to as Laser

Enhanced CVD (LECVD) or Photo Assisted CVD .

CVD may indeed be regarded as a chemical process that spans many traditional

disciplines: chemical physics of gases and plasmas, surface science, solid-state chemistry

of inorganic materials and organo metallic or organic chemistry for precursor synthesis.

Some applications of CVD

The applications of CVD are numerous and their impact on today’s society is enormous.

Here a few important examples of CVD applications are described to provide a flavor of

the impact of CVD on our everyday lives.

1. Hard coatings

Metal objects can be found everywhere and most of them are machined by some cutting

operation e.g. turning, milling or drilling. As an example, if one considers the amount of

machined parts in an ordinary car and then considers how many cars are produced

worldwide, it is obvious that metal cutting is of great importance for our society. Almost

all cutting tools use exchangeable edges, referred to as inserts, made of cemented carbide.

The great majority of inserts are coated with a hard, wear-resistant thin film that prolongs

their lifetime by several orders of magnitude. Although PVD processes, especially for

depositing hard nitride compounds, are emerging, CVD still is the work-horse for coating

cutting tools. A typical CVD coating for a cutting tool is a multilayer structure consisting

mainly of some of the following materials: TiN, TiC, TiC1-xNx, α-Al2O3 and κ-Al2O3.

These film stacks are deposited in a single deposition process, typically at around 50

mbar and 1000°C, and a coating batch consists of several thousands of cutting inserts.

Importantly, the properties of the individual films can be controlled with great precision

2. Functional coatings on glass



Considering total area of deposited film, the largest application of CVD is to coat window

glass. One of the most important reasons for coating a window is to prevent heat passing

through, reducing the need for cooling down or warming up buildings, and thus reducing

energy consumption. Typically films of transparent SnO2:F are used for this application.

To alter the darkness of the window via electrochromism or thermochromism, films of

WO3 or VO2 respectively are used. The coating can also reflect some of the incoming

light and for this, TiN films are employed. These films are deposited on the glass as a

final production step by an atmospheric pressure CVD technique mounted on the float

glass production line. The technique was developed by Pilkington in the mid 1980’s. A

recent development is to coat window glass with transparent TiO2, making the window

self-cleaning by breaking down dirt via photo catalysis with sunlight.

3. Microelectronics

It is fair to say that without CVD we would not have the electronics that we take for

granted today. All sorts of electronic devices are constructed from stacks of thin layers

with highly controlled electrical properties and CVD is often the method of choice for

depositing these thin layers. High process temperature is often not an issue for Si that

form the bedrock of most of our everyday electronics devices, as well as for the emerging

high frequency and high power electronics and light-emitting diodes based on SiC and

nitrides. Therefore CVD processes with process temperatures above 1000°C can be used;

these processes are carried out close to thermodynamic equilibrium and do not suffer

from particle bombardment. The film quality is therefore generally very high, with few

defects in the films. The alternative to CVD would be PVD which is done further from

thermodynamic equilibrium and often with a substantial amount of particle bombardment

which gives rise to crystal defects. As mentioned above, ALD-grown high-k dielectric

films have proven to be vital for a new generation of nanometer-scale transistors , where

standard CVD is unable to deliver the required quality and uniformity at the thickness

scale of just a few nanometers. Now that the utility of ALD in the semiconductor industry

has been proven, it is being targeted for the deposition of a variety of materials in ultra-

thin layers, particularly as interface control and three-dimensional structures become

more important with continued down-scaling.

Gas-permeation barriers amongst all deposition techniques, ALD is unique in enabling

nanometer-thin, pinhole-free films that are conformal over features at all length scales. By

a happy coincidence, one of the most successful ALD processes across a wide

temperature range is that of Al2O3, which is highly impermeable to 9 oxygen gas and



water vapor. It is therefore possible to use ALD to coat a variety of objects with an Al2O3

coating that is impermeable to these gases, while also being so thin (on the order of 10

nanometers) that the optical and mechanical properties of the object are almost

unaffected. Examples include reduced CO2 permeability through ALD-coated PET

bottles and moisture/oxygen diffusion barriers for organic light-emitting diodes in flexible

display technology.

References:

1] Don Okpala V. Uche , “Solgel technique: A veritable tool for crystal growth”,

Advances in applied science research 2013 ,4(1) :506-510

2] Henrik Pedersen and Simon D. Elliott, “ Studying chemical vapor deposition

processes with theoretical chemistry”, Springer verlag.



7. Emerging Trends in Automotive Engineering

R.V.Pethkar

Asst. Professor

Not too many people know automotive trends the way the staff does at The Ohio

State University's Center for Automotive Research (OSU CAR). This interdisciplinary

research center at OSU's College of Engineering focuses on advanced electric propulsion

and energy storage systems, engines and alternative fuels, intelligent transportation and

vehicular communication systems, autonomous vehicles, vehicle chassis systems, and

vehicle safety.

"One of the biggest trends right now in automotive engineering is improving

engine efficiency and fuel economy," says Giorgio Rizzoni, director of OSU CAR. "This

includes downsizing, down-speeding, direct fuel injection, and boosting."

Other engineering trends focus on improving transmissions (adding speeds),

accessory load reduction through the intelligent energy management of other vehicle

components, vehicle electrification, hybridization, improved battery management

systems, new battery chemistries, and power electronics.

"Weight reduction in vehicle subsystems is also being tested by using lightweight

structures made from alternative materials such as aluminum, magnesium, composites,

plastics, and multi-material construction," adds Rizzoni.

OSU CAR battery aging laboratory. Image: OSU CAR

Battery Systems

Battery management systems are being designed to meet performance, life, and

warranty goals for both batteries and their monitoring and management systems.

"Automakers need to fully understand how varying operational limits affect the life of

battery systems through extensive testing and modeling, followed by developing



sophisticated algorithms to track and predict various parameters, such as state of charge

and state of health through the life of the battery," comments Rizzoni.

In order to expand battery operating range and reduce costs, some researchers are

designing and testing new battery chemistries and subsystems. Advanced chemistries

could allow batteries to operate through greater temperature extremes, last longer, and

reduce weight and cost. Other efforts are being made to reduce the cost of the ancillary

systems, such as cooling, to further reduce the total cost of the battery system.

Downsizing and Turbocharging

The two main benefits in downsizing an internal combustion engine are

thermodynamic and mechanical. "From a thermodynamic point of view, the engine

operation will move towards higher loads, at which the engine efficiency is higher," says

Rizzoni. "From the mechanical point of view, the positive aspect lies in the reduction of

the friction in the piston units, together with the reduction of the number of cylinders."

Downsized engines are lighter than conventional engines, thereby reducing

vehicle mass and the improving vehicle fuel consumption. Turbocharging recovers the

energy of the exhaust gasses to increase the inducted charge, therefore increasing the

power-to-displacement ratio. "A downsized and turbocharged engine has the potential to

have the same or better performance as a non-downsized, normally aspirated engine, with

the advantage of a significant increase of fuel efficiency," says Rizzoni.

Advanced Combustion Modes

Engineers are working to increase the efficiency of internal combustion engines

by developing several advanced combustion modes. One of these modes is called

(homogeneous charge compression ignition) HCCI. In the HCCI combustion, a highly

homogenized mixture of air, fuel, and combustion products from the previous cycle is

auto-ignited by compression. "This combustion mode aims at combining the advantages

of modern diesel and gasoline combustion processes, namely low emissions and high

efficiency," states Rizzoni.

Another research trend targets ways to recover the energy that is normally

dissipated through the coolant and the exhaust gas systems of automotive powertrains

using innovative waste heat recovery devices. These systems can convert thermal energy

into mechanical or electrical energy, thus increasing the overall efficiency of the vehicle.

Organic Rankine cycle, thermoelectric systems, turbocompounding, and recuperative

thermal management systems all have potential for significantly increase engine

efficiencies.



A smaller but still significant aspect of fuel-efficiency research is called

"intelligent energy management." "This ability to more intelligently control the accessory

loads in a vehicle—such as the alternator or power steering, etc.—will also contribute to

better gas mileage," says Rizzoni. "With smarter control of these loads and the addition of

stop-start technology there can be significant increases in fuel economy, with small or no

increase in total vehicle cost."



8. VFA Welding For Joining High-Strength Metals

P. B. Patil

Asst. Professor

Connecting the pieces, whether it be for a bridge, boiler or small-scale medical device, is

perhaps the most basic part of the manufacturing and construction process, and welding is

one of the primary methods to do so. But the advent of lighter, high-strength metals used,

for example, in automotive manufacturing has made the welder’s job more difficult

because high heat and re-solidification can weaken the material along the bond. Now,

Ohio State University materials science devised a solution that joins the new materials

without melting.

A new VFA welding method may help cars become stronger and lighter

Their system is called vaporized foil actuator welding (VFA), and works using a high-

voltage capacitor bank to produce a very short electrical pulse within a thin piece of

aluminium foil. The foil vaporizes within microseconds and the resulting hot gas pushes

pieces of metal together at very high speed, joining them without melting. The bond is

produced by impact so there is not a seam of weakened metal that is the result of melting.

Mostly developing new processes based on VFA can help to solve the problem with

joining new materials, especially in automotive manufacturing. One of the biggest

potential applications is in auto body construction. Manufacturers use hot stamped steels

with remarkable high strength. There are aluminium alloys in door panels. Joining

aluminium to steel and aluminium to aluminium are outstanding problems.

In Impulse Manufacturing Laboratory, VFA tests have successfully welded aluminium

with steel and other metals using collision velocities ranging from 200 meters per second

to one kilometre per second.



Microscope view of copper (top) welded to titanium (bottom) using VFA technique

Weld joint at full strength and join a very wide variety of materials uses much less

energy, ten percent to twenty percent of the energy used in fusion spot welding process.

VFA will offer a better alternative to resistance spot welding, where a high electrical

current passes through pieces of metal. The metal’s natural electrical resistance creates

heat, melts and forms a weld. But the weld loses strength and the process is very energy

intensive.

An aluminium foil actuator, polyimide tape is used to electrically insulate the conductor

from the VFA assembly

The process utilizes a thin metal conductor. When electrical current stored in the

capacitor bank is released, the conductor is heated above its energy of sublimation before

it has time to melt, according to the lab. The metal conductor vaporizes directly into a gas

and quickly expands. The pressure pulse from the expanding gas drives the weld, joining

the two pieces of metal at the atomic level. Seen under a microscope, the bond is

illustrated by curls where the veins of the materials loop and wrap around each other.

VFA technique is two to three times stronger with aluminium than resistance spot

welding to escalate its potential by developing equipment that can make multiple welds,

scaling the tooling to demonstrate its robustness.



9. Development of the Nano Electronic Nose As Gas Sensors

A. M. Pirjade

Asst. Professor

The human nose has been used as an analytical tool in many industries to measure the

quality of food, drinks, perfumes and also cosmetic and chemical products. It is

commonly used for assessing quality through odour and this is carried out using sensory

panels where a group of people fills out questionnaires on the smells associated with the

substance being analysed. These sensory panels are extremely subjective as human smell

assessment is affected by many factors. Individual variations occur and may be affected

by physical and mental health as well as fatigue. For this reason, gas chromatography and

mass spectrometry have been employed to aid human panels to assess the quality of

products through odour evaluation and identification and also to obtain more consistent

results. However, these assistive techniques are not portable, they tend to be expensive

and their performance is relatively slow. The solution to the shortcomings of sensory

panels and the associated analytical techniques is the electronic nose (e-nose). E-nose

systems utilize an array of sensors to give a fingerprint response to a given odour, and

pattern recognition software then performs odour identification and discrimination. The e-

nose is a cost- effective solution to the problems associated with sensory panels and with

chromatographic and mass-spectrometric techniques and can accommodate.

Keywords: Electronic nose (e-nose) , nano sensors, chromatography , odour.

E-nose system

The e-nose attempts to emulate the mammalian nose by using an array of sensors that can

simulate mammalian olfactory responses to aromas. The odour molecules are drawn into

the e-nose using sampling techniques such as headspace sampling, diffusion methods,

bubblers or preconcentrators. The odour sample is drawn across the sensor array and

induces a reversible physical and/or chemical change in the sensing material, which

causes an associated change in electrical properties, such as conductivity. Each “cell” in

the array can behave like a receptor by responding to different odours to varying degrees.

These changes are transuded into electrical signals, which are preprocessed and

conditioned before identification by a pattern recognition system as shown in Figure 1.

The e-nose system is designed so that the overall response pattern from the array is

unique for a given odour in a family of odours to be considered by the system



Figure 1: Comparison of the mammalian factory system

E-nose sensor response to odorants

The response of e-nose sensors to odorants is generally regarded as a first order time

response. The first stage in odour analysis is to flush a reference gas through the sensor to

obtain a baseline. The sensor is exposed to the odorant which causes changes in its output

signal until the sensor reaches steady-state. The time during which the sensor is exposed

to the odorant is referred to as the response time while the time it takes the sensor to

return to its baseline resistance is called the recovery time. The next stage in analysing the

odour is sensor response manipulation with respect to the baseline. This process

compensates for noise, drift and also for inherently large or small signals. The sensitivity

is the measure of the change in output of a sensor for a change in the input . In the e-nose

sensors, the sensitivity of the sensor to the odorant is the change in the sensor output

parameter ( y), i.e. resistance for a change in the concentration of the odorant (x).

Conclusions :

Conducting polymer composite, intrinsically conducting polymer and metal oxide

conductivity gas sensors, SAW and QCM piezoelectric gas sensors, optical gas sensors

and MOSFET gas sensors have been discussed in this paper. These systems offer

excellent discrimination and lead the way for a new generation of “smart sensors” which

will be the future commercial markets for gas sensors.

References

[1] Albert, K.J. and Lewis, N.S. (2000), “Cross reactive chemical sensor arrays”, Chem.

Rev., Vol. 100, pp. 2595-626.

[2] Behr, G. and Fliegel, W. (1995), Sensors and Actuators B: Chemical, Vol. 26 Nos 1-3,

pp. 33-7.



10. Study of Powder mixed Electro Dicharge Machining

M. M. Salgar

Asst. Professor

Optimization of process parameters in powder mixed electrical discharge

machining (PMEDM). The use of powder particles to the electrical discharge machining

(EDM) dielectric fluid innovate some process variables and creates the conditions to

achieve ahigher surface quality in large machined areas.The analysis was carried out

carried out by using silicon cabide powder and fruit in the final surface were evaluated. In

this article siliocon carbide powder having grain size 30 micron with proportion 1g/lit is

used.EDM ipol oil is used as a dielectric with copper electode and machining is done on

AISID3 material.The apprisal was done by surface morphologic analysis, Metal recast

layer and Heat affected zone and Micro hardness of work piece were measured A result

adduces influence of the silicon powder in the reduction of crater dimensions, white-layer

thickness and surface roughness. In addition that precise control of powder concentration

and electrical parameters is a requirement for achieving an improvement in surface

quality.

In general, application of EDM is not constrained by the hardness or the material

strength to be machined. EDM may be used to machine any conductive material another

added advantage of a EDM is that there is no direct contact between the tool and work

piece during machining and cooling effects induced by machining process, a thermally

affected layer will get deposited on the work piece. The structure of this layer is quite

different from the parent material. The defects such as voids, cracks etc. cause an overall

deterioration of mechanical properties of the work piece.

Because of EDM enormous improvement in machining process has been achieved in

recent years. The capability of machining intricate parts and difficult to cut material has

made EDM as one of the most popular machining processes. The contribution of EDM to

industries such as cutting new hard materials make EDM technology remains

indispensable.

Several researches are conducted to increase EDMed surface quality. In fact, the addition

of these type of particles in the dielectric promotes the gap increasing and results in a

drastic reduction of both the capacitive effect influence and the abnormal discharge

occurrence[1].Mixing of additives powder into the dielectric reduces the electrical

capacitance across the discharge gap by increasing the gap size. As a result, better



dispersion of sparks and improvement in the discharge characteristic. To enhance the

machined surface properties and prevent the surface defects, a technique called powder

mixed electrical discharge machining (PMEDM), is now being used. In this method, fine

powder of a specific material (usually Aluminum) is mixed into the dielectric fluid of

EDM to increase the process quality.



11. Stunning Micro photos Capture Boozy Beauty in Italian

Cocktails

G. B. Pawar

Asst. Professor

A new series of photographs taken using microscopy highlights the beauty in

Boozy beveragesith just a trick of the light. The images are created (without Photoshop)

long used light microscopes and polarizing filters to study the mineral structures in rocks.

Now, Cesare has turned to photographing alcoholic drinks, capturing the sugars that

crystallize as drops of the drink dry. The technique is the same as working with rocks,

though it requires more patience

Fig : Campari is a dark-red liqueur made from citrus and herbs

Whereas rocks can be sliced into thin sections relatively quickly, a drop of drink

can take weeks to dry. This technique is called transmitted polarized light microscopy. It

can sound complicated but simply means that we observe, under an optical microscope,

something which light passes through, and that this light is polarized. The light bulb is

below the sample, at the base of the microscope.

The sample needs to be transparent to light. Before hitting the sample, the light

passes through a polarizing filter, like the lens of sunglasses. Then, using another

polarizer above the sample, we can disclose the colors, called "inference colors" that

pervade these micrographs. Note that the polarizes are colorless! understanding the

formation of interference colors is quite complicated. Let us just say that these colors are

the result of the propagation of polarized light into crystalline matter and that the color

depends on the nature of the solid, on its thickness, and on the orientation of its crystal

structure with respect to the polarized light. Using this technique routine for a geologist. It

can capture small areas of specimen, from a few millimeters to less than a millimeter



across, and show its internal constitution. Patches of different colors represent different

crystals. Polarizing microscopy is a scientific tool that helps scientists understand the

mineralogical composition and geological history of a rock.

Typical pattern of crystallized drinks is the radial texture of sugar crystals. It is

apparent in several images by the arrangement of color patches in thin stripes that

converge toward a center, like petals of a flower, and display a symmetrical distribution

of colors. It derives from a fast crystallization starting from a single point. Differences in

colors are related to a different orientation of the crystals or to differences in thickness,

such as for the limoncello micrographs.The photos demonstrate that the same substance,

with the same thickness, can display different interference colors depending on its

orientation with respect to the polarized light.



12. Hydrophobic and hydrophilic: How surfaces attract or repel

water

P. M. Wadekar

Asst. Professor

Sometimes water spreads evenly when it hits a surface; sometimes it beads into tiny

droplets. We observed this on Ketchup bottle and even on lotus leaf and opposite

phenomena in case of detergent in water. While people have noticed these differences

since ancient times, a better understanding of these properties, and new ways of

controlling them, may bring important new applications.

Materials with a special affinity for water — those it spreads across, maximizing contact

— are known as hydrophilic. Those that naturally repel water, causing droplets to form,

are known as hydrophobic. Both classes of materials can have a significant impact on the

performance of power plants, electronics, airplane wings and desalination plants, among

other technologies, says Kripa Varanasi, an associate professor of mechanical engineering

at MIT. Improvements in hydrophilic and hydrophobic surfaces could provide ketchup

bottles where the condiment just glides right out, glasses that never fog up, or power

plants that wring more electricity from a given amount of fuel.

Hydrophilic and hydrophobic materials are defined by the geometry of water on a flat

surface — specifically, the angle between a droplet’s edge and the surface underneath it.

This is called the contact angle.

If the droplet spreads, wetting a large area of the surface, then the contact angle is less

than 90 degrees and that surface is considered hydrophilic, or water-loving (from the

Greek words for water, hydro, and love, philos). But if the droplet forms a sphere that

barely touches the surface — like drops of water on a hot griddle — the contact angle is

more than 90 degrees, and the surface is hydrophobic, or water-fearing.

But the terminology doesn’t stop there: Most current research on hydrophobic and

hydrophilic materials is focused on extreme cases — namely, superhydrophobic and

superhydrophilic materials. Though the definitions of these terms are less precise,

surfaces where tight droplets form a contact angle of more than 160 degrees are

considered superhydrophobic. If the droplets are spread out nearly flat, with a contact

angle of less than about 20 degrees, the surface is superhydrophilic.

“In a lot of cases, it’s the extreme behavior that’s useful in engineering,” says Evelyn

Wang, an associate professor of mechanical engineering at MIT who specializes in

superhydrophobic materials. For example, the surfaces of condensers in desalination



plants or power plants work best when they are superhydrophobic, so droplets constantly

slide off and can be replaced by new ones. Conversely, for applications where water

flows over a surface to keep it from overheating, it’s desirable to have a superhydrophilic

material, to assure maximum contact between the water and the surface.

Why do these phenomena happen? It’s essentially a matter of surface chemistry, which is

determined by the characteristics of the materials used. The shape of a surface can also

amplify the effects: For example, if a material is hydrophobic, creating nanopatterns on

its surface can increase the contact area with a droplet, amplifying the effect and making

the surface superhydrophobic. Similarly, nanopatterning of a hydrophilic surface can

make it superhydrophilic. (There are exceptions, however, where special kinds of

patterning can actually reverse a material’s ordinary properties.)

It gets more complicated when things are moving — as is often the case in real-world

situations. For instance, when a flat surface is tilted, any droplets on it can begin to slide,

distorting their shapes. So beyond measurements of static contact angles, a complete

understanding of a surface’s properties also requires analysis of how the contact angles at

its advancing (front) and receding (back) edges differ when the surface is slanted.

Because the natural world is full of hydrophobic and hydrophilic surfaces, the basics of

the phenomenon have been known by scientists for at least two centuries. For example,

the lotus leaf is a well-known example of a hydrophobic material, protecting the water-

dwelling plant from becoming waterlogged. Some species, such as the stenocara beetle of

Africa’s Namib Desert, combine both traits: The insect’s back and wings have

hydrophilic bumps that encourage condensation from fog; these are surrounded by

hydrophobic troughs, which collect the resulting droplets and funnel them toward the

beetle’s mouth — allowing it to survive in one of Earth’s driest places.

One area of modern interest in hydrophobic and hydrophilic surfaces has to do with

energy efficiency. Superhydrophobic surfaces under development by researchers at MIT

and elsewhere could lead to better heat transfer in power-plant condensers, increasing

their overall efficiency. Such surfaces could also increase the efficiency of desalination

plants.

New technologies have also contributed to the field: The ability to create nanopatterned

surfaces, with bumps or ridges just a few billionths of a meter across, has enabled a new

generation of water-grabbing and water-shedding materials; new high-resolution imaging

of surfaces in motion has enabled better understanding of the processes involved.



Research enabled by new technologies makes it possible to understand, and manipulate,

these behaviors at a level of detail unthinkable a decade or two ago. But sometimes the

new methods show how well scientists had things figured out long ago: “It’s amazing,”

Varanasi says, “that some of the things we can validate now were predicted a century

ago.”



13. Heat Transfer Enhancement Using Self-rotating And

Stationary Twisted Tape.

A. R. Mane

Asst. Professor

Heat transfer enhancement techniques refer to different method used to increase

rate of heat transfer without affecting much the overall performance of the system. These

techniques are used in heat exchangers. These techniques broadly are of three type

passive, active, compound techniques. The use of passive devices like twisted tapes

roughness element, wires inserts etc. are effective method of heat transfer augmentation.

The optimum shape for twisted tapes can also be developed based on maximization of

heat transfer and minimization of friction factor regarding fluid used in the system. This

paper conducted comprehensive &comparative review on experimental &numerical

Works taken by researchers on self-rotating &stationary twisted tape. Both heat transfer

coefficient and friction factor increase with the decreasing of twisted ratio.

Introduction:

Now days twisted tape inserts have widely been applied for enhancing the

convective heat transfer in various industries, due to their effectiveness low cost &easy

setting up. The heat transfer techniques enable heat exchanger to operate at smaller

velocity, but still achieve the same or even higher heat transfer coefficient.[1] This means

that a reduction of pressure drop corresponding to less operating cost generally, heat

transfer enhancement techniques may be classified into three main classes; active,

passive, compound method. In active method, external power is used for heat transfer

enhancement. It seems an easy method in several applications however it is quite complex

from design point of view. That is why it is of limited use due to external power

requirements. Apart from active methods, there is no involvement of external power

supply in passive methods of heat transfer enhancement.

Passive methods utilize energy within the system which leads to increase fluid

pressure drop. The use of special surface geometry gives high thermal performance as

compared to plain surface. Twisted tapes, wire coils, dimples, ribs, fins, micro fins etc. are

different passive devices which are used to enhance heat transfer rate. Also, tube with

longitudinal inserts is also an effective passive method of heat transfer enhancement.

Passive techniques are associated with the use of modifications in surfaces and geometries

in a flow channel with the help of inserts. Earlier, it was very difficult to work with

complex geometries due to their fabrication constraints but with the advancement in



manufacturing technology it is now quite possible to apply new geometries in heat

transfer enhancement techniques.

Compound heat transfer method is a hybrid technique which involves the use of

both active and passive methods. The method is quite complex and have limited

applications. Burgles has presented a review on different types of developed convective

heat transfer enhancement techniques. The use of twisted tape inserts is one of the

important passive methods of heat transfer enhancement. Twisted tapes are generally the

metallic strips which are twisted in some septic shape and dimensions and inserted across

the flow. They are also considered as swirl flow devices and act as tabulators used to

impart swirl flow which leads to the increase in heat transfer coefficient.[1]

Pitch and twist ratio are the important parameters used to study the performance

of twisted tapes. Pitch of a twisted tape is the length between two points on a plane,

parallel to the axis of the tape whereas twist ratio of a twisted tape is the ratio of pitch to

inside diameter of the tube. As one of the passive method techniques, tube inserts

technology has been widely used in the heat exchanger such as twisted tape, helical

spring, ribs, conical nozzle, and conical ring, etc. The tube inserts can be divided in to

two broad categories: stationary and self-rotating. The stationary inserts have the

relatively fixed position in plain tube. The self-rotating inserts are defined as such inserts

which can automatically rotate while the fluid flows through the tube. The self-rotating

inserts can strengthen the heat transfer efficiency and achieve the on-line anti-scaling and

descaling effect.

Although literatures comprehensively review the thermal performance twisted

tape in heat exchangers, the thermal and anti-fouling performance of self rotating twisted

tape will be focused in the present paper. The findings provide useful references for future

development of twisted tape.[2]

Categories of twisted tapes:

Twisted tape can be manufactured in a variety of forms by suitable techniques

using the aluminum, copper, steel or polymer plastic. It can be applied in various areas in

certain conditions. Firstly, it is indispensable to define some important parameters used in

this report to facilitate understanding and discussing the characteristics of twisted

tape.The basic parameter for twisted tape is twist ratio.



Fig. 1. Structure sketch map of twisted tape.[1]

= -------------------[1]

Where,

H is the half length of twist pitch, which is defined as the distance between two points that

are on the same plane, measured parallel to the axis of a twisted tape.

B. is the thickness of twisted tape

D is the inside diameter of the tube.

The configuration sketches of self-rotating twisted tapes are shown in Table 1.[1]

The commonly used stationary twisted tape can be classified into typical twisted tape,

multiple twisted tapes, varying length, alternate-axes and pitches twisted tape, twisted

tape with slots, holes, cuts, twisted tape with rod and varying spacer, twisted tape with

attached fins and tapes with different surface modifications, which are shown in Table

2.[1]

Mechanism of heat transfer enhancement:

Twisted tapes have been generally applied as heat transfer enhancing devices in

heat exchanger. In this part the main and effective mechanisms of heat transfer

enhancement are analyzed for better understanding of twisted tape property.The velocity

vector contour of a plain tube and a tube inserted with twistedtape areshownin Figs. 2 and

3[1], respectively. The fluid in tube with twisted tape in Fig. 3[1]


The centrifugal force induced by tangential velocity accelerates the mixing between the

mainstream zone and the near wall zone.

The main mechanisms of heat transfer enhancement due to twisted tape include:

1. The reduction of a hydraulic diameter of heat transfer tube causes an increase of

flow velocity and curvature.

2. The velocity increase near the tube wall due to the blockage of the twisted tape

which reduces thickness of the boundary layer.

3. The induced swirling flow makes a better fluid mixing between the core and the

near-wall flow regions. This swirling flow can be seen in Fig. 4.[1]

Fig. 4. The flow characteristic with twisted tape[1]

As one of the most favorable passive techniques, twisted tape insert is a kind of

vortex generator which can break the boundary layer and reduce the thickness of the

laminar bottom layer. It has been proposed that such tapes induce turbulence and

Fig 2. The velocity vector contour

of plain tube[1] Fig.3. The velocity vector contour of

tube inserted with twisted tape[1]



superimposed vortex motion causing a thinner boundary layer. Consequently, this results

in higher heat transfer coefficient.

Development of self-rotating twisted tapes:

1. Impact of self-rotating twisted tapes on the enhancement efficiency: The twisted tape which is fixed with the rotating device on both ends of heat

exchange tube can rotate around the center by itself while the fluid in tube flows. All the

performances of tube with a self-rotating twisted tape are compared with that of a plain

tube without twisted tape. A conclusion can be drawn that both the heat transfer rate and

the pressure drop increase with the tube fitted with self-rotating twisted tape. The increase

of the total heat transfer coefficient is between 12% and 62%. In order to visually describe

the pressure drop characteristics difference between the self-rotating twisted tape and

stationary twisted tap. The results show that the pressure drop of the tube fitted with self-

rotating twisted tape and stationary twisted tape is about 2.02 and 2.73 times compared to

smooth tube, respectively. found that the polypropylene twisted tapes have better

comprehensive performance than the aluminum twisted tapes. The results show that the

oblique teeth twisted tape could automatically rotate and enhance heat transfer with low

flow velocity of 0.5 m/s. This is because of the additional rotating moment formed by the

oblique teeth on the twisted tape. With the increasing of W/D, both the Nusselt number

and the friction decrease. In particular, the friction and Nusselt number increases with the

increase of twist rate Y, which is different from the smooth twisted tape.

2. Impact of self-rotating twisted tapes on the anti-fouling and descaling:

Fouling is formed on the tube wall in the heat exchanger, which can lead to

decline of production capacity, material loss, increase the energy consumption. In order to

solve this problem, kinds of self-rotating twisted tapes have been put forward by many

researchers. The anti-fouling and descaling mechanism of self-rotating twisted tape is

mainly disturbing the boundary layer. The results indicate that the average adhesive

velocity of fouling for the tubes inserted with twisted tape is only 54% that of the smooth

tubes, the average dynamic thermal resistance of fouling is 30% smaller than that of the

smooth tube.

Development of stationary twisted tapes:

A variety of stationary twisted tape inserts are commonly investigated and applied in

the heat exchangers to enhance the heat transfer efficiency. The stationary twisted tapes

cannot rotate automatically and have higher pressure drop. These tapes have length equal

to that of exchanger tube.



1) Impact of typical twisted tapes on the enhancement efficiency:

In the tested range, the heat transfer coefficient increases with decrease in twist

ratio for water and nanofluid using the twisted tapes. Experiment results are obtained that

the use of reduced twist ratio value provides greater overall heat transfer performance and

the heat transfer coefficient increments up to 45%. The pressure drop penalty sharply

decreases with the increase of vapor quality.

Difference between self rotating & stationary tapes:

The stationary twisted tapes can generate the swirl flow in the fluid flow in heat

exchanger tube, which can enhance the flow turbulence intensity, and lead to better

convection heat transfer compared to the plain tube with an axial flow.

The self-rotating twisted tapes can strengthen the heat transfer efficiency and achieve on-

line automatic anti-scaling and descaling effect. The self-rotating twisted tapes change the

direction of fluid flow, form a rotational flow, fluid at the tube surface mixed and disrupt

the development of boundary layer. Compared with the stationary twisted tapes, the self-

rotating twisted tapes have the dual effect for heat exchanger.

Conclusion:

1. Compared with the stationary twisted tapes, the heat transfer enhancement and the

function of online anti-scaling and descaling can be obtained with the self-rotating

inserts in tube. Means, the tube with self-rotating twisted tapes gives the lower

pressure drop.

2. The twisted tape, which is relevant to minimum pressure drop conjugate with the

maximum heat transfer rate, is the optimal shape.

3. Twisted tape inserts increases the heat transfer rate in the heat exchanger by

increasing turbulence in the fluid flow.

4. Turbulent flow or swirl flow increases the thermal contact by reducing boundary layer

thickness.

5. The heat transfer rate increases with decreasing twist ratio and increasing Reynolds

number.

References:

1) Dingbiao Wang, “A comparative review of self-rotating and stationary twisted tape

inserts in heat exchanger”, Renewable and sustainable energy review 53 (2016), 433-449.

2) Himanshu Nautiyal ,“Heat Transfer augmentation using twisted tape insert”,

Renewable and sustainable energy review 63 (2016), 193-225.



14. Residual Stress

G. N. Rakate

Asst. Professor

1. Introduction

In many cases residual stresses are one of the main factors determining the engineering

properties of parts and structural components. This factor plays a significant role, for

example, in fatigue of welded elements. The influence of residual stresses on the

multicycle fatigue life of butt and fillet welds can be compared with the effects of stress

concentration. The main stages of residual stress management are considered in this

chapter with the emphasis on practical application of various destructive and

nondestructive techniques for residual stress measurement in materials, parts, and welded

elements. Some results of testing showing the role of residual stresses in fatigue processes

as well as aspects and examples of ultrasonic stress-relieving are also considered in this

chapter. The presented data on residual stresses are complimentary to the detailed review

of various methods of residual stress analysis considered in two handbooks on residual

stresses published by the Society of Experimental Mechanics (SEM) in 1996 and 2005.

2. Importance of Residual Stress

Residual stress can significantly affect the engineering properties of materials and

structural components, notably fatigue life, distortion, dimensional stability, corrosion

resistance, and brittle fracture. Such effects usually lead to considerable expenditure in

repairs and restoration of parts, equipment, and structures. For this reason, residual stress

analysis is a compulsory stage in the design of parts and structural elements and in the

estimation of their reliability under real service conditions. Systematic studies had shown

that, for instance, welding residual stresses might lead to a drastic reduction in the

fatigue strength of welded elements. In multicycle fatigue (N>106 cycles), the effect of

residual stresses can be comparable to the effect of stress concentration.

Even more significant are the effects of residual stresses on the fatigue life of

welded elements in the case of relieving harmful tensile residual stresses and introducing

beneficial compressive residual stresses in the weld toe zones. The results of fatigue

testing of welded specimens in the as-welded condition and after the application of

ultrasonic peening shows that, in the case of non-load-carrying fillet welded joint in

high-strength steel, redistribution of residual stresses resulted in approximately twofold

increase in the limit stress range.



The residual stresses are therefore one of the main factors determining the engineering

properties of materials, parts, and welded elements, and should be taken into account

during the design and manufacturing of different products. Although certain progress has

been achieved in the development of techniques for residual stress management,

considerable effort is still required to develop efficient and cost-effective methods of

residual stress measurement and analysis as well as technologies for the beneficial

redistribution of residual stresses.

3. Definition of Residual Stresses

Residual stresses (RS) can be defined as those stresses that remain in a material or body

after manufacture and material processing in the absence of external forces or thermal

gradients. Residual stresses can also be produced by service loading, leading to

inhomogeneous plastic deformation in the part or specimen. Residual stresses can be

defined as either macro- or microstresses and both may be present in a component at any

one time. Residual stresses can be classified as

Type I: Macro residual stresses that develop in the body of a component on a scale

larger than the grain size of the material

Type II: Micro residual stresses that vary on the scale of an individual grain

Type III: Micro residual stresses that exist within a grain, essentially as a result of the

presence of dislocations and other crystalline defects

It is the first level or macroscopic (type I) residual stress that is of interest to mechanical

engineers and design offices and that is considered in this article.

4. Origin of Residual Stresses

Residual stresses develop during most manufacturing processes involving material

deformation, heat treatment, machining or processing operations that transform the shape

or change the properties of a material. They arise from a number of sources and can be

present in the unprocessed raw material, introduced during manufacturing or arise from

in-service loading. The origins of residual stresses in a component may be classified as

• differential plastic flow

• differential cooling rates

• Phase transformations with volume changes etc.

For instance, the presence of tensile residual stresses in a part or structural element are

generally harmful since they can contribute to, and are often the major cause of, fatigue

failure and stress-corrosion cracking.


Fig. 1 Distribution of longitudinal (oriented along the weld) residual stresses near the

fillet weld in a bridge span. x is the distance from the weld toe [3]

Compressive residual stresses induced by different means in the (sub)surface layers of

material are usually beneficial since they prevent origination and propagation of fatigue

cracks, and increase wear and corrosion resistance. Examples of operations that produce

harmful tensile stresses are welding, machining, grinding, and rod or wire drawing.

Figure 1 shows a characteristic residual stress profile resulting from welding.

The residual stresses were measured by an ultrasonic method in the main wall of a bridge

span near the end of one of the welded vertical attachments. In the vicinity of the weld the

measured levels of harmful tensile residual stresses reached 240 MPa. Such high tensile

residual stresses are the result of thermoplastic deformations during the welding process

and are one of the main factors leading to the origination and propagation of fatigue

cracks in welded elements.

Fig. 2 In-depth profile of residual stress in 2014-T6 aluminum alloy produced by

conventional (CS) and ultrasonic (US) shoot peening



On the other hand, compressive residual stresses usually lead to performance benefits and

can be introduced, for instance, by peening processes such as shot peening, hammer

peening, laser peening, and ultrasonic peening. Figure 2 shows characteristic distributions

of beneficial compressive residual stress in the surface layers of material resulting from

conventional and ultrasonic shot peening processes.

5. Residual Stress Management: Measurement, Fatigue Analysis, and Beneficial

Redistribution

It is very important to consider the problem of residual stress as a complex problem

including, at least, the stages of determination, analysis, and beneficial redistribution of

residual stresses. The combined consideration of these stages of the residual stress

analysis and modification gives rise to so-called the residual stress management (RSM)

concept approach . The RSM concept includes the following main stages

Stage 1. Residual stress determination:

• Measurement: destructive, nondestructive

• Computation

Stage 2. Analysis of the residual stress effects:

• Experimental studies

• Computation

Stage 3. Residual stress modification (if required):

• Changes in technology of manufacturing/assembly

• Application of stress-relieving techniques

The main stages of residual stress management are considered in this chapter with the

emphasis on examples of practical application of various destructive and nondestructive

techniques for residual stress measurement in materials, parts, and welded elements.

Some results of testing showing the role of residual stresses in fatigue processes as well

as beneficial modification of residual stresses directed mainly towards fatigue life

improvement are also considered. New engineering tools such as a computerized

ultrasonic system for residual stress measurement and a technology and corresponding

compact system for ultrasonic hammer peening are also introduced.

References

1. J. Lu (Ed.):Handbook on Residual Stress,Vol.1(SEM, Bethel 2005) p. 417

2. V. Trufyakov, P. Mikheev, Y. Kudryavtsev:Fatigue Strength of Welded

Structures(Harwood Academic, London 1995) p. 100



3. Y. Kudryavtsev, J. Kleiman, O. Gushcha: Ultrasonic measurement of residual

stresses in welded railway bridge, Structural Materials Technology: An NDT

Conference (Technomic Publishing Co. Inc., Atlantic City 2000) pp. 213–218

4. J.Lu,P.Peyre,C.OmanNonga,A.Benamar, J. Flavenot: Residual stress and

mechanical surface treatments, current trends and future prospects, Proceedings of

the 4th International Congress on Residual Stresses (ICRS4) (SEM, 1994) pp.

1154–1163



15. GYROSCOPIC PRECESSIONAL EFFECT ON HELICOPTER

A. A. Shinde

Assistant Professor

1. Gyroscopic precession

Gyroscopic precession is a phenomenon occurring in rotating bodies in which an applied

force is manifested 90 degrees later in the direction of rotation from where the force was

applied. Although precession is not a dominant force in rotary-wing aerodynamics, it

must be reckoned with because turning rotor systems exhibit some of the characteristics

of a gyro. This diagram shows how precession affects the rotor disk when force is applied

at a given point:

Fig.1 Gyroscopic Precession

A downward force applied to the disk at point A results in a downward change in disk

attitude at point B. And upward force applied at Point C results in an upward change in

disk attitude at point D.

Forces applied to a spinning rotor disk by control input or by wind gusts will react

as follows:

This behavior explains some of the fundamental effects occurring during various

helicopter maneuvers. For example, the helicopter behaves differently when rolling into a

right turn than when rolling into a left turn. During roll into a left turn, the pilot will have

to correct for a nose down tendency in order to maintain altitude. This correction is



required because precession causes a nose down tendency and because the tilted disk

produces less vertical lift to counteract gravity. Conversely, during a roll into a right turn,

precession will cause a nose up tendency while the tilted disk will produce less vertical

lift. Pilot input required to maintain altitude is significantly different during a right turn

than during a left turn, because gyroscopic precession acts in opposite directions for each.

2. Retreating Blade Stall

Fig. 2 Retreating Blade Stall

A tendency for the retreating blade to stall in forward flight is inherent in all

present day helicopters and is a major factor in limiting their forward speed. Just as the

stall of an airplane wing limits the low speed possibilities of the airplane, the stall of a

rotor blade limits the high speed potential of a helicopter. The airspeed of the retreating

blade (the blade moving away from the direction of flight) slows down as forward speed

increases. The retreating blade must, however, produce an amount of lift equal to that of

the advancing blade. Therefore, as the airspeed of the retreating blade decreases with

forward aircraft speed, the blade angle of attack must be increased to equalize lift



throughout the rotor disk area. As this angle increase is continued, the blade will stall at

some high forward speed.

As forward airspeed increases, the "no lift" areas move left of center, covering

more of the retreating blade sectors:

This requires more lift at the outer retreating blade portions to compensate for the

loss of lift of the inboard retreating sections. In the area of reversed flow, the rotational

velocity of this blade section is slower than the aircraft airspeed; therefore, the air flows

from the trailing to leading edge of the airfoil. In the negative stall area, the rotational

velocity of the airfoil is faster than the aircraft airspeed; therefore air flows from leading

to trailing edge of the blade. However due to the relative arm and induced flow, blade

flapping is not sufficient to produce a positive angle of attack. Blade flapping and

rotational velocity in the negative lift area are sufficient to produce a positive angle of

attack, but not to a degree that produces appreciable lift.

This figure shows a rotor disk that has reached a stall condition on the retreating side:

Fig. 3 Angle of attack distribution during retreating blade stall

It is assumed that the stall angle of attack for this rotor system is 14 degrees.

Distribution of angle of attack along the blade is shown at eight positions in the rotor

disk. Although the blades are twisted and have less pitch at the tip than at the root, angle

of attack is higher at the tip because of induced airflow.



Upon entry into blade stall, the first effect is generally a noticeable vibration of

the helicopter. This is followed by a rolling tendency and a tendency for the nose to pitch

up. The tendency to pitch up may be relatively insignificant for helicopters with semirigid

rotor systems due to pendular action. If the cyclic stick is held forward and collective

pitch is not reduced or is increased, this condition becomes aggravated; the vibration

greatly increases, and control may be lost. By being familiar with the conditions which

lead to blade stall, the pilot should realize when his is flying under such circumstances

and should take corrective action.

The major warnings of approaching retreating blade stall conditions are:

Abnormal vibration

Pitchup of the nose

Tendency for the helicopter to roll in the direction of the stalled side.

When operating at high forward airspeeds, the following conditions are most likely to

produce blade stall:

High blade loading (high gross weight)

Low rotor RPM

High density altitude

Steep or abrupt turns

Turbulent air

When flight conditions are such that blade stall is likely, extreme caution should be

exercised when maneuvering. An abrupt maneuver such as a steep turn or pullup may

result in dangerously severe blade stall. Aircraft control and structural limitations of the

helicopter would be threatened.

Blade stall normally occurs when airspeed is high. To prevent blade stall, the pilot must

fly slower than normal when:

The density altitude is much higher than standard

Carrying maximum weight loads

Flying high drag configurations such as floats, external stores, weapons, speakers,

floodlights, sling loads, etc.

The air is turbulent

When the pilot suspects blade stall, he can possibly prevent it from occurring by

sequentially:

Reducing power (collective pitch)

Reducing airspeed



Reducing "G" loads during maneuvering

Increasing RPM to upper allowable limit

Checking pedal trim

In severe blade stall, the pilot loses control. The helicopter will pitch up violently

and roll to the left. The only corrective action then is to accomplish procedures as

indicated previously to shorten the duration of the stall and regain control.

3. SUMMARY

Weight, lift, thrust, and drag are the four forces acting on a helicopter. The cyclic

for directional control, the collective pitch for altitude control, and the antitorque pedals

to compensate for torque are the three main controls used in a helicopter.

Torque is an inherent problem with single-main-rotor helicopters. Gyroscopic

precession occurs approximately 90° in the direction of rotation from the point where the

force is applied. Dissymmetry of lift is the difference in lift that exists between the

advancing and retreating half of the rotor disc.



16. A Review on Natural Fiber Hemp as a Composite Material

S. A. Mullya

Asst. Professor

INTRODUCTION

Composite materials are widely used in Aero industry, Automobile industry,

sports equipments, Construction materials, Marine applications. Hemp is the cannabis

plant, especially grown for obtaining fibers and bio-composite material. Global market

consists of more than 25000 products for hemp. In 1950 in USA, hemp was discarded due

to its use in intoxicated drugs such as marijuana due to presence of THC

(Tetrahydrocannabinol) in it, but due to use of modern breeding techniques the amount of

THC is reduced to almost zero. This industrial hemp has huge by-products than any other

natural fiber. Hemp as compared with cotton produces more fiber, also its cultivation time

and cost is less. The mechanical properties of the hemp fibers and glass fibers are same,

but hemp fibers have relatively low density. As it is natural fiber it will reduce the cost of

product and provide high power to weight ratio. Now-a-days natural fibers are used in the

building materials which will maintain the temperature in the house. Natural and cellulose

fibers are used in polymer and cement matrices to improve their strength and fracture

resistance properties.

Hemp is an ancient plant that has been cultivated for millennia. In the 16th

Century, Henry VIII suggested farmers to plant the crop in large scale to provide

materials for the British Naval fleet. A large supply of hemp was needed for the

construction of battleships and their components. Hemp paper was used for maps, logs,

and even for the Bibles that sailors may have brought on board. From 1937 until the late

1960s the United States government recognized that industrial hemp and marijuana were

two different varieties of the cannabis plant. After the Controlled Substances Act was

passed, hemp was no longer recognized as being distinct from marijuana. Modification in

the hemp seed is possible by using some breeding techniques. Hemp can be classified as

population type, use of plant as fiber cultivars, flowering type, gender and geographic

origin. Countries like China, Canada and some countries from Europe are showing lot of

interest in breeding. Hemp is wind pollinated crop where male and female flowers are

different. There are various methods of breeding are available. Methods for hemp

breeding have changed in year. But the methods like mass selection, cross breeding,

inbreeding, hybrid breeding, marker assisted breeding are mostly used in many countries.



Sukhdeep Singh suggested that Industrial hemp having very good tensile strength but

Reinforcement of hemp fibers in HDPE matrix reduces the tensile strength. Florence

Collet studied about thermal conductivity of hemp concrete and states that thermal

conductivity of hemp concrete depends both on its formulation, its density and water

content.

MATERIALS AND METHODS

Structure

Fig. Structure of hemp fibers.

Composition

The structure of hemp fiber consists of three main constituents which are

celluloses, hemicellulose and lignin. It was experimentally found, the content of each

constituent in hemp. Hemp stem, depending on the species, consists of approximately 20-

40% (by weight) of fiber, which is outside of the stem and 60-80% (by weight) of wood

(hurds). Chemical composition of raw hemp fiber is as follows: cellulose (55-72%),

hemicellulose (8-19%), lignin (2-5%), wax (<1%) and minerals (4%). Hurds have higher

content of lignin (19-21%) and hemicellulose (31-37%), but lower amount of cellulose

(36-41%)

Formation method

Hemp fibre reinforced polyethylene (fresh and recycled) composite is

manufactured by injection moulding technique for varying fiber contents from 10% to

30%. Hemp hurds were prepared from Lithuanian dried hemp stalks, from which long

fibers were manually separated. After removal of long fibers, hemp stalks were

conditioned for 24 hours at 23±3°C temperature and 50±5% relative air humidity. Stems



were rotary grinded by mill with an output of 1.1 kW and speed of 2800 rev/min. 30

seconds of grinding time was chosen for the experiment. In the case of shorter grinding

hurds are not grinded to the required fractions of 2.5-5 mm, and longer grinding causes a

significant amount of dusts, which have adverse effect on composite formation because

they only increase the need for water. After grinding, short fibers were separated, and the

remaining hemp hurds were sieved through laboratory sieves. Sieved hurds with a

fraction of 5, 2.5 mm were used for tests. Hemp hurds with coarse fraction were grinded

again, and dusts (smaller than 0.063 mm) were removed.

PROPERTIES OF HEMP

As natural fiber hemp is the strongest when we compare it with other fibers

Basically some of the properties of the hemp fiber are listed below due to which this fiber

is globally famous.

Mechanical and thermal properties

It has been reported that the tensile properties of the hemp fiber were 800 to 1000

MPA at their untreated form. The properties such as toughness, stiffness, flexural

strength, interfacial shear strength can be acquired by reinforcing it with different

thermoplastics and thermoset polymers. Hemp fiber is one of the strongest and stiffest

available natural fibers with high aspect ratio and cellulose content and therefore has

great potential for use in composite materials. Hemp composites can be used in the

designing of ultra lightweight airplanes. By using hemp composites in the manufacturing

of the vehicle we can reduce the overall weight which will ultimately lead to increase in

the economy of the vehicle. It is important to note that the plant which is grown for

manufacturing the body parts will ultimately consumes the CO2.

Researchers mentioned that the need to reduce green house gases emission

produced by building sector leads to research of less impacting materials that can replace

traditional one and hemp is one of many. It is also very breathable fiber which will

maintain the air ventilating in the building and also acts as a good insulating medium. The

walls made from the hemp are fire resistance also.

Physical properties and their field uses

The major problem of using the artificial fiber is they take so much time to

degrade in the environment but hemp is biodegradable fiber. Sustainable development has

become a subject of major attention in national and international organizations in

developed and developing countries. Thee development of methods and techniques



guiding the use, recycling and replacement of natural resources and the upholding of the

earth’s productivity. To build sustainable and affordable building it is needed to design

efficient building materials with following characteristics thermal insulation, sound

absorption and sound insulation. These physical properties are well combined in the hemp

also the use of hemp concrete will also make houses very breathable and when we

compare it with the cost it will cost as much as by conventional wall but with more

benefits .The density of the fiber is observed to be very less and it will also provide good

amount of power to weight ratio.

APPLICATIONS

Hemp fibers are commonly used in the automotive industries mainly for reinforcement of

door panels, passenger rear decks, pillars and boot linings. Hemp fibers are also used in

the pulp and paper industry. Insulation is another important area of hemp fiber

application. It is also used for construction purpose, textile industries. Hemp seeds can be

used to make protein powder, oil, milk& butter. Hemp provides a sustainable, renewable

& natural alternative to toxic fossil fuels.

References

[1] Alexander Naughton, Mizi Fan, Julie Bregulla. Fire resistance characterisation of

hemp fibre reinforced polyester composites for use in the construction industry.

Composites: Part B.

[2] Denis Mihaela Panaitescu, Cristian Andi Nicolae, Zina Vuluga, Catalin Vitelaru,

Catalina Gabriela Sanporean, Catalin Zaharia, Dorel Florea, Gabriel Vasilievici.

Influence of hemp fibers with modified surface on polypropylene composites. Journal of

Industrial and Engineering Chemistry (2016)

[3] Giedrius Balčiūnasa, Sigitas Vėjelisb, Saulius Vaitkusc, Agnė Kairytėd. Physical

Properties and Structure of Composite Made by Using Hemp Hurds and Different

Binding Materials. Procedia Engineering 57 ( 2013 ) 159 – 166.

[4] Adel Ramezani Kakroodi, Yasamin Kazemi, Denis Rodrigue. Mechanical,

rheological, morphological and water absorption properties of maleated

polyethylene/hemp composites: Effect of ground tire rubber addition. Composites: Part B

51 (2013) 337–344.



17. Personal Transport vehicle

K. I. Nargatti

Asst. Professor

Dean Kamen, inventor and entrepreneur, first penned the idea of a revolutionary new type

of personal transportation during the mid 1990’s. Nowadays, his invention, the Personal

transport vehicle Human Transporter (HT), is a common sight in America and is sold

around the world. As of early 2005, it is available for purchase in Australia.

The Personal transport vehicle (HT) is a vehicle which has two coaxial wheels driven

independently by a controller that balances the vehicle both with and without a rider. The

balancing is regulated by feedback from an array of tilt sensors and gyroscopes. The

controller uses advanced State Space (SS) control making the system very robust and

responsive. It is robust enough to accept riders of different weights and responsive

enough to provide adequate balancing for different riders and riding styles.

In daily life when human have to travel a small distance i.e. about 20 Km people are use

two wheeler vehicle which is not economical as well as creates pollution in the

environment which is danger’s to human life. It has also harmful effect on animals so it is

required to take care of humans as well as Animals. So to overcome above problem

people are designing a self-balance vehicle for Personal Transport as it can be used in

shopping Malls, in non-polluting zone and in the industries for material transport.

Fig 1. Personal Transport Vehicle


The Personal Transport (PT) Vehicle is a vehicle which has two coaxial wheels driven

independently by a motor that balances the vehicle both with and without a rider. The

balancing is regulated by feedback from accelerometer sensors and gyro sensors. The

signal is given to PID controller which gives signal to Processor. Then Processor gives

signal to motor controller which controls the speed of the motor i.e. it take action

according to the situation. The PT uses technology called dynamic stabilization to

maintain its balance and move forward or backward. If rider is lean Forward, the speed of

motor increases and if it lean towards backward, then speed of motor decreases to obtain

balancing. It is robust enough to accept riders of different weights and responsive enough

to provide adequate balancing for different riders and riding styles.

Fig 2. How the PTV works – leaning forward and back

References

1. Alonso D’Arrigo, Silvio Colombi & Alfred C. Rufer, “JOE: A Mobile, Inverted

Pendulum” IEEE Transactions on Industrial Electronics, Grasser, Felix, vol.49, 2002.

2. Mikael arvidson, Jonas Karlsson” “Design, construction and verification of self

balancing vehicle”, 2002.

3. M. Thompson, J. Beula, Juliett Marry”, “Design And Fabrication Of Fail Safe Personal

transport vehicle”, International Journal of Mechanical and Industrial Technology, Vol. 2,

Issue 1, 2003, pp: 78-82

4. Ankit S. Khanzode, Ashish G. Masne, Mohd. Shahzad Gulam Ali, Akshay P. Tale,

Kamalkishor G Maniyar, “Mechanical Segway”, International Journal of Engineering and

Technical Research, Volume-4, Issue-3, March 2016, pp: 92-96



18. Nanotechnology

H. H. Patil

Asst. Professor

Nanotechnology ("nanotech") is manipulation of matter on an atomic, molecular,

and supramolecular scale. The earliest, widespread description of

nanotechnology referred to the particular technological goal of precisely manipulating

atoms and molecules for fabrication of macro scale products, also now referred to

as molecular nanotechnology. A more generalized description of nanotechnology was

subsequently established by the National Nanotechnology Initiative, which defines

nanotechnology as the manipulation of matter with at least one dimension sized from 1 to

100 nanometers. Because of the variety of potential applications (including industrial and

military), governments have invested billions of dollars in nanotechnology research. Until

2012, through its National Nanotechnology Initiative, the USA has invested 3.7 billion

dollars; the European Union has invested 1.2 billion and Japan 750 million dollars.

Nanotechnology as defined by size is naturally very broad, including fields of

science as diverse as surface science, organic chemistry, molecular biology,

semiconductor physics, micro fabrication, molecular engineering, etc. Scientists currently

debate the future implications of nanotechnology. Nanotechnology may be able to create

many new materials and devices with a vast range of applications, such as in nano

medicine, nano electronics, biomaterials energy production, and consumer products. On

the other hand, nanotechnology raises many of the same issues as any new technology,

including concerns about the toxicity and environmental impact of nano materials and

their potential effects on global economics.

History of Nanotechnology:

The concepts that seeded nanotechnology were first discussed in 1959 by

renowned physicist Richard Feynman in his talk There's Plenty of Room at the Bottom, in

which he described the possibility of synthesis via direct manipulation of atoms. The term

"nano-technology" was first used by Norio Taniguchi in 1974, though it was not widely

known. Inspired by Feynman's concepts, K. Eric Drexler used the term "nanotechnology"

in his 1986 book Engines of Creation: The Coming Era of Nanotechnology, which

proposed the idea of a nano scale "assembler" which would be able to build a copy of

itself and of other items of arbitrary complexity with atomic control. Also in 1986,

Drexler co-founded The Foresight Institute to help increase public awareness.



Second, Fullerenes were discovered in 1985 by Harry Kroto, Richard Smalley,

and Robert Curl, who together won the 1996 Nobel Prize in Chemistry. C60 was not

initially described as nanotechnology; the term was used regarding subsequent work with

related graphene tubes (called carbon nano tubes and sometimes called Bucky tubes)

which suggested potential applications for nano scale electronics and devices.

Fundamentals of Nano measures:

One nanometer (nm) is one billionth, or 10−9, of a meter. By comparison, typical carbon-

carbon bond lengths, or the spacing between these atoms in a molecule, are in the

range0.12–0.15 nm, and a DNA double-helix has a diameter around 2 nm. On the other

hand, the smallest cellular life-forms, the bacteria of the genus Mycoplasma, are around

200 nm in length. By convention, nanotechnology is taken as the scale range 1 to 100

nm following the definition used by the National Nanotechnology Initiative in the US.

Nano materials

The nano materials field includes subfields which develop or study materials having

unique properties arising from their nano scale dimensions.

Interface and colloid science has given rise to many materials which may be useful in

nanotechnology, such as carbon nano tubes and other fullerenes, and various

nanoparticles and nano rods. Nano materials with fast ion transport are related also to

nanoionics and nano electronics.

Nano scale materials can also be used for bulk applications, most present commercial

applications of nanotechnology are of this flavor.

Progress has been made in using these materials for medical applications.

Nano scale materials such as nano pillars are sometimes used in solar cells which

combats the cost of traditional Silicon solar cells.

Recent application of nano materials include a range of biomedical applications, such

as tissue engineering, drug delivery, and biosensors.

Applications:

As of August 21, 2008, the Project on Emerging Nanotechnologies estimates that over

800 manufacturer-identified nanotech products is publicly available, with new ones

hitting the market at a pace of 3–4 per week. The project lists all of the products in a

publicly accessible online database. Most applications are limited to the use of "first

generation" passive nano materials which includes titanium dioxide in sunscreen,

cosmetics, surface coatings, and some food products; Carbon allotropes used to

produce gecko tape; silver in food packaging, clothing, disinfectants and household



appliances; zinc oxide in sunscreens and cosmetics, surface coatings, paints and outdoor

furniture varnishes; and cerium oxide as a fuel catalyst.

Further applications allow tennis balls to last longer, golf balls to fly straighter and

even bowling balls to become more durable and have a harder

surface. Trousers and socks have been infused with nanotechnology so that they will last

longer and keep people cool in the summer. Bandages are being infused with silver

nanoparticles to heal cuts faster. Video game consoles and personal computers may

become cheaper, faster, and contain more memory thanks to

nanotechnology. Nanotechnology may have the ability to make existing medical

applications cheaper and easier to use in places like the general practitioner's office and at

home. Cars are being manufactured with nano materials so they may need

fewer metals and less fuel to operate in the future.

Health and environmental concerns due to Nano technology:

Nano fibers are used in several areas and in different products, in everything from aircraft

wings to tennis rackets. Inhaling airborne nanoparticles and nano fibers may lead to a

number of pulmonary diseases, e.g. fibrosis. Researchers have found that when rats

breathed in nanoparticles, the particles settled in the brain and lungs, which led to

significant increases in biomarkers for inflammation and stress response and that

nanoparticles induce skin aging through oxidative stress in hairless mice.

A two-year study at UCLA's School of Public Health found lab mice consuming nano-

titanium dioxide showed DNA and chromosome damage to a degree "linked to all the big

killers of man, namely cancer, heart disease, neurological disease and aging".

A major study published more recently in Nature Nanotechnology suggests some forms

of carbon nano tubes – a poster child for the “nanotechnology revolution” – could be as

harmful as asbestos if inhaled in sufficient quantities. Anthony Seaton of the Institute of

Occupational Medicine in Edinburgh, Scotland, who contributed to the article on carbon

nano tubes said "We know that some of them probably have the potential to cause

mesothelioma. So those sorts of materials need to be handled very carefully." In the

absence of specific regulation forthcoming from governments, Paull and Lyons (2008)

have called for an exclusion of engineered nanoparticles in food. A newspaper article

reports that workers in a paint factory developed serious lung disease and nanoparticles

were found in their lungs.



19. Development of Thin Film Coating of CNT for Tools used

in EDM processes

V. S. Ganachari

Asst. Professor

Electric Discharge machining (EDM) is a non-conventional manufacturing

technology widely used in various industries. In EDM process while machine operated on

high current and pulse on time values it leads to increase tool wear rate. The aim of this

research work was to create a methodology to minimize the tool wear rate at high values

of energy related parameters in EDM. The experimental work investigated comparative

study with coated tool electrode and with non coated tool electrode. Copper electrodes

were used as tool electrode then it coated with carbon nano tubes for further experimental

work. Design of experiment (DOE) was done with Taguchi method and results discussed

with ANOVA. The machining results showed that the tool wear rate (TWR) decreases

and material removal rate (MRR) increases with coating of CNT on copper electrodes.

INTRODUCTION:

In recent years, in the machining field, the requirements of the cutting tools are becoming

increasingly diverse, including higher speed, higher efficiency and also increased

performance stability, extended tool life, and reduced cost to use under harsher condition

ever in normal environment. Materials such as carbide, Sintered carbide, cemented and

CBN are used but using these tools independently, the diverse needs are not perfectly

obtained. It is therefore, coated tools were invented. Initially in 1969 the TiC and WC

coated tools became normal in metal machining industries because these coating

consequently improve the ability and life of tool up to 200 to 300% or more. In cutting

tools it is necessary requirement that a tool must have high hardness, high strength,

abrasion resistant, and as well as it must be chemically inert to prevent the chemical

reaction between the newly generated surface of work piece and that of tool. To be

effective the coating must be fine grained free of binders and porosity. Naturally the

coating must be metallurgic to the substrate [1].Coated tools are finding wide acceptance

in many manufacturing applications. Coated tools have two or three times the wear

resistance than the best uncoated tools. It is therefore, these tools have a broader range of

applications. The advancement of the coated carbide tool technology has greatly

attributed the advancement in manufacturing technology. There are various types of

coating methods such as Chemical Vapour Deposition and Physical Vapour Deposition,

Sol-gel method, Hot dip method, Doctor Blade method, Thermo-reactive Diffusion,



Dynamic Compound Deposition. The industrialists had to increase their production, due

to pressure to ever increasing human needs. This lead to improve and innovations in the

existing technology, which in turn helped to increase the productivity and efficiency then

existing units. Industrial production is largely dependent on the state of technology and its

advancements. Machinery and tools play a vital role in production process. In fact it is the

key factor for improving productivity. This motivated the scientists and technicians to

think of modifying and improving tools. In the year 1984, the process of coating tools

was first introduced. This was important landmark in the history of industrially advanced

countries. The invention of coating tools which has helped to increase the productivity

nearly 2.5 times than the original. Thus, coating process is born for the various

applications like electro-discharge machine coating tools, conventional machine tools,

CNC machine [2].

Coating Material for EDM Tool

Coating is covering that is applied to the surface of an object which is referred as

substrate. Coating may be applied to change the properties of the substrate such as

corrosion resistance or wear resistance, adhesion etc. Coating adds completely new

property such as magnetic response or electrical conductivity and forms essential part of

finished product. A major consideration for most coating process is that the coating is to

be applied at controlled thickness. The main objective of coating on tool is to minimize

tool wear rate and increase life of tool. There are different types of coating materials for

tool. Aluminium oxide (Al2O3), Titanium Nitride (TiN), Zirconium Oxide (ZrO2),

Diamond coating, Epoxy Resin, Titanium Diaboride (TiB2), Zirconium Nitride (ZrN),

Chromium Nitride (CrN), Cubic Boron Nitride (CBN), Aluminium Titanium Nitride

(AlTiN), Silicon, Bronze Nano Graphite coating, Cemented Carbide, Silver coating,

Carbon nanotube, Si doped Mg are the examples of coating material. Some characteristics

of coating materials are as follow:Physical characteristics of coating material like

hardness coefficient of friction, coefficient of thermal conductivity, young’s module as

are listed in Table 1

Table 1: Comparison of mechanical properties

Coating TiN Diamond Epoxy Resin CNT

Hardness (GPa) 21.7 150 5.62 152

Coefficient of friction 0.5 0.1 0.25 0.03 – 0.2

Thermal Conductivity(W/mK) 11.9 1000 0.35 3500

Young’s Modulus of Elasticity 251 1050 0.51 1.8 TPa


In of them CNT has higher electrical conductivity, high hardness, low coefficient

of friction and high young’s modulus of elasticity. So Carbon Nanotubeselected as

coating material for electrode of Electrical Discharge Machine. Carbon Nanotube are

hexagonally shaped arrangement of carbon atoms that have been rolled into tubes.

Nanotubes have been constructed with length-to-diameter ratio of up to 132,000,000:1.

Nanotubes are categorized as single-walled nanotubes (SWNTs) and multi-walled

nanotubes (MWNT). Figure 1 shows the structure of CNT.

Figure 1: Structure of CNT

References

SWNT MWNT

[1] Fang Liu and Yon Zhang, 2014, “Situ growth of carbon nanotubes from nickel based

coating and wear properties”.

[2] SubhasDebnath, 2012, “Improvement in tool life of electroplated diamond tools by

Ni-based carbon nanotube composite coatings”.

[3] Atsushi Hirata, Nobuaki Yoshioka, 2004, “Sliding friction properties of carbon

nanotube coatings deposited by microwave plasma chemical vapour deposition”.

[4] Jacob M .WernikandShaker A. Meguid, 2010, “Recent developments in

Multifunctional Nanocomposites using Carbon Nanotubes”.

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