Non conventional Machining processes For B.Tech Mechanical Engineering

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Presented By: Group 5
Members-
1. Hirakjyoti Nath (MEB18032)
2. Chinmoy Baruah (MEB18030)
3. Dipjyoti Das (MEB18031)
4. Abhilash Hazarika (MEB18033)
NON CONVENTIONAL MACHINING
PROCESSES
A PRESENTATION FOR TEST 3

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CONTENTS
Sl.
No.
Topic Member Name
1 INTRODUCTION
HIRAKJYOTI NATH
(MEB18032)
2 ADVANTAGES OF NON CONVENTIONAL
MACHINING PROCESSES
3 CLASSIFICATION OF NON CONVENTIONAL
MACHINING PROCESSES
4 WATER JET MACHINING
5 ULTRA SONIC MACHINING
6 ABRASIVE JET MACHINING
CHINMOY BARUAH
(MEB18030)
7 CHEMICAL MACHINING
8 ELECTROCHEMICAL MACHINING

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Sl. No. Topic Member Name
9 ELETROLYTIC GRINDING
DIPJYOTI DAS
(MEB18031)
10 ELECTRICAL DISCHARGE MACHINING
11 WIRE ELECTRICAL DISCHARGE MACHINING
12 ELECTRON BEAM MACHINING
ABHILASH HAZARIKA
(MEB18033)
13 LASER BEAM MACHINING
14 PLASMA ARC CUTTING
CONTENTS

INTRODUCTION
 Machining is the process in which a material
(often metal) is cut to a desired final shape and
size by a controlled material-removal process.
 In recent years, many harder materials have
been developed having their applications in
Aerospace, Nuclear Engineering etc. where the
machining by traditional methods is very difficult
and uneconomical.
 Non conventional machining is directly done by
using some sort of indirect energy for machining
e.g. sparks , laser, heat, chemical etc.
 Nontraditional machining processes are widely
used to manufacture geometrically complex and
precision parts for aerospace, electronics and
automotive industries.

ADVANTAGES OF NON- CONVENTIONAL MACHINING
1) Higher accuracy and surface finish
2) Greater Machinability
3) Less/no wear
4) Tool life is more
5) Quieter operation
6) Less Environment hazards

CLASSIFICATION OF NON-CONVENTIONAL MACHINING
PROCESSES
Non conventional
Machining
Processes
Mechanical
Processes
Chemical
Processes
Electrochemical
Processes
Electro thermal
Processes
The different Non-Conventional Machining Processes can be broadly Classified into the following
types based on the energy source used-
A) Mechanical Processes
B) Chemical Processes
C) Electrochemical Processes
D) Electro thermal Processes

PROCESSES
A) Mechanical Processes-
These processes utilizes mechanical action for removing Material. The Processes
which come under this category are-
i) Ultrasonic Machining (USM) – Utilizes Mechanical Vibrations at High Frequency
ii) Water Jet Machining (WJT – Uses the high velocity water jet to cut material
iii) Abrasive Jet Machining (AJM) –Utilizes the high energy of water and also the
cutting property of Abrasives
B) Chemical Processes- These are the processes which utilizes some chemical reactions for
cutting out material. This includes-
i) Chemical Machining (CHM)- Chemical Machining is the clean removal of metal from
pre described areas without altering the integrity or properties of bthe metal by means of a
photochemical process.
C) Electrochemical Processes – It utilizes the chemical reactions and electricity for
machining. These processes include the operation of-
i) Electrochemical machining (ECM)- It is a method of removing metal by an
electrochemical process.

PROCESSES
D) Electrothermal Processes-
This kind of Processes employ a combination of electrical energy
and heat to achieve material removal process. These include the
following machining Processes-
i) Laser Beam Machining (LBM)- A machining method in which the
cutting operation is performed by laser light.
ii) Electron Beam Machining(EBM)-In the electrical beam machining,
electrical energy is used to generate the electrons with high energy
and thus cutting is performed
iii) Electro-Discharge Machining (EDM)- Based on removing material
from a part by means of a series of repeated electrical discharges
between tools, called electrodes, and the part being machined in the
presence of a dielectric fluid.
iv) Plasma Arc Machining (PAM)- Plasma arc machining is a
metal removal process in which the metal is removed by focusing a
high-velocity jet of high temperature (11,000°C to 30,000°C) ionized
gas on the workpiece.

Introduction-
Water Jet Machining (WJM) also called water jet
cutting, is a non-traditional machining process in
which high-velocity jet of water is used to remove
materials from the surface of the workpiece. WJM
can be used to cut softer materials like plastic,
rubber or wood.
In order to cut harder materials like metals or
granite, an abrasive material is mixed in the water.
When an abrasive material is used in the water for
the machining process than it is called Abrasive
Water Jet Machining (AWJM).
If the work material is brittle it will fracture,
if it is ductile, it will cut well .
WATER JET MACHINING (WJM)

Construction of Water Jet Machining -
Water Jet Machining Set-up consists of the following Parts-
1. Reservoir – That stores the water required for machining purposes
2. Hydraulic Pump
It is used to circulate the water from the storage tank during the machining
process.
Reservoir
INTENSIFIER
Direction Control
Valve
Flow Regulator
Valve
Hydraulic
Pump
Nozzle
Abrasive

3. Intensifier- The pump delivers water to the intensifier at low pressure of about 5 bars.
The Intensifier increases the pressure of water to very high value like 4000-5000 bar.
4. Accumulator- It stores the high pressurized water temporary. It supplies that fluid when a
large amount of pressure energy is required.
5.Flow Control Valve:
It controls the pressure and direction of the water jet.
6. Flow Regulator or Valve:
The flow of the water is regulated with the help of the flow regulator.
7. Nozzle:
It is a device that is used to convert the pressure energy of water into kinetic energy in
water jet machining. Here nozzle converts the pressure of water jet into high-velocity beam
of water jet. The tip of the nozzle is made of ruby or diamond to prevent it from erosion.

8. Mixing chamber or tube:
It is a vacuum chamber where the mixing of abrasive particles into water takes place.
8. Drain and Catcher System:
After the machining, the debris and machined particles from the water are separated out
with the help of the drain and catcher system. It removes the metal particle and other
unwanted particles from the water and sends it back to the reservoir for further use.

Working Principle-
It is based on the principle of water erosion.
When a high-velocity jet of water strikes the
surface, the removal of material takes place.
Pure water jet is used to machine softer
materials.
But to cut harder materials, some abrasive
particles mixed with the water for machining
and it is called as AWJM (Abrasive Water Jet
Machining)
Abrasive Materials-
The most commonly used abrasive particles in
AWJM are garnet and aluminum oxide. Sand
(Si02) and glass beads are also used as
abrasive. The function of the abrasive particles
is to enhance the cutting ability of the water jet.

1. Assuming no losses, determine water jet velocity, when the water pressure is
4000 bar, being issued from an orifice of diameter 0.3 mm.
Solution: Here, Velocity of Water Jet, 𝑉𝑊= ?
Water Pressure, P = 4000 bar = 4000 X 105
Pa
Density of water, ρ= 1000 kg/𝑚3
𝑉𝑊 =
2𝑃
ρ
=
2𝑋4000𝑋〖10〗^5 𝑃𝑎
1000
= 894 m/s
2. If the mass flow rate of abrasive and mass flow rate of water are 1 kg/min and
3.79 kg/min respectively, determine the abrasive water jet velocity assuming no loss
during mixing process. Given, water jet velocity is 894 m/s.
Solution: Here, Mass flow rate of Abrasive, 𝑚𝑤= 1 kg/min
Mass flow rate of Water, 𝑚𝑎𝑏𝑟= 3.79 kg/min
Abrasive Water Jet Velocity, 𝑉𝐴𝑊𝐽= ?
Velocity of Water Jet, 𝑉𝑊𝐽 = 894 m/s
𝑉𝐴𝑊𝐽= (
1
1+
𝑚𝑎𝑏𝑟
𝑚𝑤
)𝑉𝑊𝐽
Numerical Problems on Water Jet Machining-

Numerical Problems on Water Jet Machining-
Solution-
𝑉𝐴𝑊𝐽 =
1
1+
1
3.79
× 894
= 707 m/s

ADVANTAGES
 It has multidirectional cutting capacity.
 No heat is produced.
 Wetting of the workpiece material is minimal.
 There is no deflection to the rest of the workpiece.
 The tool does not wear and, therefore, does not need
sharpening.
 The process is environmentally safe.
 Hazardous airborne dust contamination and waste disposal
problems are eliminated.
 Eliminates costly and complicated tooling, which reduces
turnaround time and lowers the cost.
 Grinding and polishing are eliminated, reducing secondary
operation costs.

Disadavantages
 It cannot used for machining material which degrade in
presence of water.
 Low metal removal rate.
 High initial cost.
 Thick material cannot be machined easily.

APPLICATIONS OF WATER JET MACHINING
The technique tends to be most commonly used for
cutting:
 Body parts.
 Engine components (aluminium, titanium, heat-resistant
alloys)
 Titanium bodies for military aircraft.
 Interior cabin panels.
 Custom control panels and structural components for
special purpose aircraft.
 Trimming of turbine blades

ULTRASONIC MACHINING (USM)-
Introduction-
Ultrasonic Machining (USM) also called as
ultrasonic vibration machining is a machining
process in which material is removed from the
surface of a part by low amplitude and high
frequency vibration of a tool against surface of
material in the presence of abrasive particles.
It is applicable to both conductive and
nonconductive materials. Particularly suited for
very hard and/or brittle materials such as
graphite, glass, carbide, and ceramics.

The Components of a USM System are as
follows:
1. Electronic Oscillator- The electronic
oscillator is used to generate high-
frequency alternating current. The
frequency is in the ultrasonic range (20-
40KHz). It is the high frequency
generator.
2. Transducer - Transducer used in USM
converts the electrical energy into
mechanical vibration. There are mainly
two types of transducer is used in USM;
i) piezoelectric transducer or
ii) magnetostrictive transducer.
Piezoelectric transducer: Piezoelectric crystal such
as barium titanate is vibrated when applying
alternative current. It converts electrical energy to
mechanical energy at high efficiency (above 90%)
without any cooling.
Construction of Ultrasonic Machining

ii) Magnetostrictive transducer: Ferromagnetic material like nickel alloys are placed inside the
coil of wire. The alternating current passes through the coil create an alternating magnetic field.
Magnetostriction effect creates the vibrational movement.
3. Tool- Tool is made of ductile material like mild steel, brass to reduce the tool wear. Mass of
tool should be minimum possible so that it does not absorb
the ultrasonic energy.
4 Tool Holder- The shape of the tool holder is cylindrical or conical, or a modified cone which
helps in magnifying the tool tip vibrations. Its function is to increase the tool vibration amplitude
and to match the vibrator to the acoustic load. e.g. Titanium with Stainless Steel
5. Abrasive slurry –
Common types of abrasive used are- Boron carbide (B4C) good in general, but expensive
Silicon carbide (SiC)
glass, ceramics
Diamond (used for rubies , etc)
Liquid - Water most common
Benzene
Glycerol
Oils
Construction of Ultrasonic Machining

An electronic oscillator used to produce an alternating
current of high frequency at the ultrasonic range. This
electrical energy then used to energize the transducer which
converts electric energy into mechanical vibration. The small
amplitude and high-frequency vibration produced in
transducer then amplify using a mechanical amplifier that
holds the tool, known as concentrator.
The process is performed by a cutting tool, which oscillates
at high frequency, typically 20 -40 kHz, in abrasive slurry.
The tool is gradually fed with a uniform force.
The high -speed reciprocations of the tool drive the
abrasive grains across a small gap against the workpiece
The impact of the abrasive is the energy principally
responsible for material removal in the form of small wear
particles that are carried away by the abrasive slurry. •
The shape of the tool corresponds to the shape to be
produced in the workpiece.
Working Principle-

Problem: Glass is being machined at a MRR of 6 mm3 /min by Al2O3 abrasive grits
having a grit diameter of 150 μm. If 100 μm grits were used, what would be the MRR?
Numerical on Ultrasonic Machining-

Advantages and Disadvantages-
Advantages-
 This process is used for drilling both circular and non-circular holes in very hard materials
like carbide, ceramics, etc.
 This process is best suited for brittle materials.
 The machining operation is simple and requires less time.
 This process is economical.
Disadvantages-
 Low material cutting rate.
 High power consumption.
 Low penetration rate.
 The process is limited to the machined surface of a small size.
 Shorter tool life.
 Ultrasonic vibration machining can only be used on materials with a hardness value of at
least 45 HRC (Rockwell Hardness).

APPLICATIONS
It is mainly used for
(1) drilling
(2) grinding,
(3) Profiling
(4) coining
(5) piercing of dies
(6) welding operations on all materials which
can be treated suitably by abrasives.
(7) Used for machining hard and brittle metallic
alloys, semiconductors, glass, ceramics,
carbides etc.
(8) Used for machining round, square, irregular
shaped holes and surface impressions.

Various Work Samples Machined by USM:
1- The first picture on the left is a plastic sample that has inner grooves that are machined
using USM.
2- The Second picture (in the middle is a plastic sample that has complex details on the
surface
3- The third picture is a coin with the grooving done by USM

ABRASIVE JET MACHINING
ABRASIVES: AN ABRASIVE IS A SMALL, HARD PARTICLE HAVING SHARP EDGES
AND AN IRREGULAR SHAPED CUTTING TOOL. ABRASIVES ARE CAPABLE OF
REMOVING SMALL AMOUNTS OF MATERIAL FROM A SURFACE THROUGH A
CUTTING PROCESS THAT PRODUCES TINY CHIPS.
• BECAUSE THEY ARE HARD, ABRASIVES ALSO ARE USED IN FINISHING
PROCESSES FOR HEAT-TREATED METALS AND ALLOYS AND FOR VERY HARD
PARTS IN APPLICATIONS SUCH AS:
(a) FINISHING OF CERAMICS AND GLASSES,
(b) CUTTING OFF LENGTHS OF BARS, STRUCTURAL SHAPES, MASONRY, AND
CONCRETE,
(c) REMOVING UNWANTED WELD BEADS AND SPATTER, &
(d) CLEANING SURFACES WITH JETS OF AIR OR WATER CONTAINING ABRASIVE
PARTICLES.
• IN ABRASIVE-JET MACHINING (AJM), A HIGH-VELOCITY JET OF DRY AIR,
NITROGEN, OR CARBON DIOXIDE CONTAINING ABRASIVE PARTICLES IS
AIMED AT THE WORKPIECE SURFACE UNDER CONTROLLED CONDITIONS.

WORKING PRINCIPLE:
• A high-velocity jet of dry air, nitrogen, or carbon dioxide
containing abrasive particles (typically∼0.025mm) is aimed
at the workpiece surface under controlled conditions. As
particle impact the work surface, they cause small cracks, and
the gas stream carries both the abrasive particles and the
fractured (wear) particles away. The gas supply pressure is of
the order of 850kPa and jet velocity can be as high as 300 m/s
and is controlled by a valve.
• It consists of a mixing chamber in which abrasive particle
such as aluminium oxide, silicon carbide, diamond dust,
glass particles are used. Air or gas may be nitrogen or carbon
dioxide is used to mix with the abrasive particles. From the
mixing chamber, the mixture is supplied to the nozzle which
is the high strength of a material i.e., tungsten carbide.

APPLICATIONS
Deflashing and Trimming
Engraving
Ceramic abrading and glass frosting
Deburring
Producing intricates hole shapes in a hard and brittle material.
Cleaning and polishing the plastic, nylon and Teflon component.
Frosting of the interior surface of glass tubes.
Etching of marking of glass cylinders.

ADVANTAGES:
It has the ability to cut hard materials such as
composites, ceramics, and glass.
The complex shape can be produced in the hard and
brittle material.
Ability to cut the heat sensitive materials.
Low initial cost.

DISADVANTAGES:
 Expensive process.
 This process not suitable for mass production because
of the high maintenance requirement.
 Metal removal rate is slow.
 Nozzle wear rate is more.
 Additional cleaning is necessary.

PROBLEM. 1
For the AJM process, the ratio of the abrasive volume to carrier gas volume is 0.25.
Further, the ratio of abrasive density to carrier gas density is 25. What is the mass
ratio of abrasive to the mixture of abrasive and carrier gas ? [Gate: 2019]
Soln: As we know,
Mixing ratio (MR) =
Va
Vg
=
Vol. flow rate of abrasive particles
Vol.flow rate of carrier gas
Mass ratio (α)=
Mass flow rate of abrasive particle (Ma)
Combined mass flow rate of abrasive particle carrier gas (Ma+g)
Where, Ma = ρaVa;
Ma+g = ρaVa + ρgVg

ρa
ρg
= 25 and
Va
Vg
= 0.25
Then,
1
α
=
ρaVa+ρgVg
ρaVa
= 1 +
ρg
ρa
×
Vg
Va
= 1+
1
25
×
1
0.25
= 1.16
and α = 0.862

CHEMICAL MACHINING
• It is the clean removal of metal from pre described
areas without altering the integrity or properties of the metal
by means of a photochemical process. This process is
primarily used in creating small thin metal parts of complex
design with no burns or stresses to the parts. Chemical
Machining is a process used for metal removal purpose by
dissolution in a controlled manner from the workpiece by the
application of acidic or alkaline solution and this solution is
called etchant. The chemical machining process is widely
used to produce micro-components for various industrial
applications like micro electrochemical systems (MEMS) and
semiconductor industries.
• In chemical machining, an important factor is the cost of
reagents, maskants, and disposal-together with the cost of
cleaning the parts.

WORKING PRINCIPLE
The main working principle of chemical
machining is chemical etching. The part of
the workpiece whose material is to be
removed, is brought into the contact of
chemical called enchant. The metal is
removed by the chemical attack of enchant.
The process steps include precleaning,
masking, scribing, etching, final cleaning,
stripping, and mechanical finishing.

PROBLEM. 2
In chemical machining, the etch factor is expressed as-
a) Depth of cut/ Undercut
b) Tool Wear/Work Piece Wear
c) Undercut/Depth of Cut
d) Work Piece Wear/Tool Wear
Solution- c) During the etching process, the removal of material takes place
along the depth in an unexposed portion as well as in the inward direction
under the mask. The distance etched under the mask is called as an undercut.
While the distance etched in the exposed portion is called the depth of cut.
Etch Factor = Undercut / Depth of Cut

ADVANTAGES
It produces High precision metal parts.
Machining of work-piece from all sides of work-piece at same time.
It can done Machining of any shape & size.
High machining accuracy.
High surface finish obtained.

DISADVANTAGES
Very few metals can be machined using this machining
process.
Sometimes evolved gas get collected under the maskant and
result in uneven itching of the material.
The material removal rate is very low.

APPLICATIONS
Producing complex configurations in delicate parts.
 In aviation industries for making aircraft wing panels.
 To manufacture very thin laminations without burrs.
 For Printed Circuit Boards (PCB).
 The manufacture of burr-free, intricate stampings.

ELECTROCHEMICAL MACHINING
• In this machining, an electrolyte acts as a current
carrier and high rate of electrolyte movement in the
tool and workpiece gas washes the metal ions away
from the workpiece before they have to change to
plate onto the tool.
• It is the reverse of electroplating. Modification of this
process are used for turning, slotting, trepanning, and
profiling operation in which the electrode becomes
the cutting tool. The tool is made up of brass, copper,
bronze, or stainless steel. which is used to perform
the work on the workpiece.

WORKING PRINCIPLE
In the electrochemical process, the way that material
is removed from the workpiece is quite unique. The
electrochemical reactions take place at the anode
(workpiece) and the cathode (tool), as well as the
surrounding electrolyte fluid. As the electrical
current is applied across the electrode, ions move
between the tool and the workpiece. In
electrochemical machining, positive ions move
towards the tool, and negative ions move towards
the workpiece. This is the opposite of electroplating.
As electrons cross the gap between the workpiece
and the tool, metal ions come away from the
workpiece. These ions combine with hydroxyl ions
to form metal hydroxides which are carried away by
the electrolyte solution. The result is a smoothly
finished workpiece with the desired material
removed to create the necessary shape.

PROBLEM 3
• In electrochemical machining of pure iron a material removal rate of
600 mm3 /min is required. Estimate current requirement.
• Solution-

ADVANTAGES
Machining of hard and brittle material is possible with good quality of
surface finish and accuracy.
There is almost negligible tool wear, so the cost of tool making is an
only one-time investment for mass production.
Complex shapes can be easily machined.
There is no use of force, no direct contact between tool and workpiece.
Very close tolerances can be obtained.

DISADVANTAGES
All non-conducting materials cannot be machined.
The tool and workpiece should be chemically still with the
electrolyte solution.
Designing and making tool is difficult but its life is long
recommended only for mass production.

APPLICATIONS
 Die-sinking operations
 Drilling jet engine turbine blades
 Multiple hole drilling
 Machining steam Turbine blades within close limits
 Micro machining
 Profiling and contouring
 Rifling barre

ELECTROLYTIC GRINDING
In the process of electrolytic grinding (ELG), an
abrasive wheel much like a standard grinding wheel is used.
The abrasive wheel bond is metal, thus making it a
conducting Wheel-cathode medium.
The abrasive grains in the grinding wheel are non-
conducting and aid in removing oxides from the work
piece while helping maintain the gap between wheel and
work. ELG, like ECM, is a depleting process, and work piece
material is carried away by the circulating electrolyte.
ELG System- The basic ELG system consists of the
appropriate power supply, the electrode (metal bonded
grinding wheel), work-holding equipment, and the electrolyte
supply and filtration system. Work piece material is depleted
and goes into the electrolyte solution.

WORKING PRINCIPLE
• Electrolytic machining is a method of removing material
from metal surfaces by electrolytic etching, and electrolytic
grinding is a process that adds mechanical grinding process
to this.
Typically, with the electrolytic elution processes, some
anodic byproducts that inhibit the elution will be formed and
in some cases the elution can completely stop due to the
metal surface becoming passivated. In order to prevent this,
non-passivating solutions are selected for electrolytic
machining. In contrast, the electrolytic grinding employs
mechanical grinding by abrasive grinding media to scrape
away the passivated layer so the etching process can
continue on to the freshly exposed metal surfaces.

PROBLEM
• What is the Material Removal Rate (MRR) of a Work Piece Material of
Mass = 5 kg and Density = 1260 kg/m3 supplied with 200 A of
Current? Given Faraday’s Constant = 96485 C/mol
• Solution- Given, Mass, G = 5 kg
• Density, ρ= 1260 kg/m3
• I= 200 A
F= 96486 C/mol
We know,
𝐺𝐼
ρF
= 8.225 cc/sec

Advantages and Applications of ELG
• Because ELG is primarily electrochemical and not mechanical, as is conventional
grinding, the abrasive wheel in ELG wears little in the process. ELG is burr-free and
will not distort or overheat the work piece. The process is therefore useful for small
precision parts and thin or fragile work pieces.
• Electrolytic grinding was originally developed for grinders to produce electrolytic
machining tools, but eventually was widely applied for many hard-to-grind materials
since the method offered lower grinding heat and forces in comparison to the
conventional methods.

ELECTRICAL DISCHARGE MACHINING
Electrical Discharge machining is the
process of metal removal from the work
surface due to an erosion of metal caused by
electric spark discharge between the two
electrodes tool (cathode) and the work
(Anode). Electrical Discharge Machining is
also called or known as Spark machining,
spark eroding, burning, die sinking, wire
burning or wire erosion.

WORKING PRINCIPLE
• It consists of an electric power supply, the dielectric
medium, the tool, workpiece, and servo control.
• The work piece is connected to the positive terminal and
the tool is connected to a negative terminal of the DC
power supply.
• An air gap of 0.005 to 0.05 mm is maintained between the
tool and the work.
• The die electric fluid which is non-conductor of electricity
is forced under pressure through the gap.
• When a DC power is supplied, the fluid in the gap gets
ionized and produces a spark between the tool and work
piece, causing a local rise in temperature at about 1000
degrees Celsius, when melts the metal in a small area of
the workpiece and vaporizes.
• The DC supply generates a pulse between 40 to 3000 V
and the frequency of spark at the rate of 10000 sparks per
second can be achieved.

(continued)
• The electric and magnetic fields on heated metal cause a compressive force which removes
the metal from the work surface.
• The die electric fluid acts as a coolant carry the cooled metal from the work surface.
• The die electric fluid acts as a coolant carries the eroded metal particles which are filtered
regularly and supplied back to the tank.
• A servomechanism is used to feed the tool continues to maintain a constant gap between two
electrodes.

PROBLEM 4-
• If in a RC type generator, to get an idle time of 500 μs for open circuit
voltage of 100 V and maximum charging voltage of 70 V, determine
charging resistance. Assume C = 100 μF.
• Solution-

ADVANTAGES
It can be used for any hard material and even in the heat-treated condition.
Any complicated shapes made on the tool can be reproduced.
High accuracy of about 0.005 mm can be achieved.
Good surface finish can be achieved economically up to 0.2 microns.
Machining time is less than the conventional machining process.

DISADVANTAGES
• Excessive tool wear.
• High power consumption.
• The sharp corner cannot be reproduced.
• High heat developing causing the change in metallurgical
properties of materials.
• The workpiece must be an electrical conductor.

Applications of Electro Discharge Machining
• Drilling for micro holes in the nozzle.
• This is used in thread cutting.
• Used in wire cutting.
• Rotary form cutting.
• Helical profile milling.
• Curved hole drilling.
• Engraving operation on harder materials.
• Cutting off operation.
• The shaping of alloy steel and tungsten carbide dies.

WIRE ELECTRICAL DISCHARGE MACHINING
• Wire electrical discharge machining (WEDM) uses a metallic wire
to cut or shape a workpiece, often a conductive material, with a
thin electrode wire that follows a precisely programmed path.
Typically the electrode diameters range from 0.004″ – 0.012″
(.10mm – .30mm), although smaller and larger diameters are
available.
• During the wire cutting process there is no direct contact between
the wire and the workpiece which allows for machining without
causing any distortion in the path of the wire, or the shape of the
material. To accomplish this, the wire is very rapidly charged to a
desired voltage. The wire is also surrounded by deionized water.
When the voltage reaches the correct level, a spark jumps the gap
and melts a small portion of the work piece. The deionized water
cools and flushes away the small particles from the gap.
• The hardness of the work piece material has no detrimental effect
on the cutting speed. Extrusion dies and blanking punches are very
often machined by wire cutting.

WORKING PRINCIPLE
• Wire EDM machining works by creating an
electrical discharge between the wire or the
electrode and the work piece. As the spark
jumps across the gap, material is then removed
from the work piece and the electrode. Due to
the inherent properties of the process, Wire
EDM can easily machine complex parts and
precision components out of hard conductive
materials.
• To stop the sparking process from shorting
out, a non-conductive fluid or dielectric is also
used in the process. The waste material is
removed by the dielectric, and the process
continues.

PROBLEM 5-
• In a wire-cut EDM process the necessary conditions that have to be met for
making a successful cut are that
a) Wire and sample are electrically non-conducting
b) Wire and sample are electrically conducting
c) Wire is electrically conducting and sample is electrically non-conducting
d) Sample is electrically conducting and wire is electrically non-conducting
Solution-
Option b) : Wire and sample are electrically conducting

Advantages of Wire EDM
• High dimensional accuracy for close fitting parts.
• The tool and the workpiece do not make actual contact which allows for machining
of delicate sections and weak materials.
• The process leaves minimal burrs.
• Custom tooling is generally not needed.

Disadvantages of Wire EDM
• Slow speed.
• Conductive materials only.
• Effects of a charged environment.
• Not ideal for tubing cutoff.

ELECTRON BEAM MACHINING
INTRODUCTION
• Electron Beam Machining is a
process in which high-velocity
electrons are concentrated in a
narrow beam and then directed
towards the workpiece for
machining.
• When this high-velocity
electron strikes the workpiece,
it melts and vaporizes the
material from the workpiece.

WORKING PRINCIPLE-
• In an electron beam machining, the electrons strike the workpiece with a high
velocity. As the electron strikes the workpiece, the kinetic energy of the electron
changes into heat energy.
• The heat energy produced is used to melt and vaporize the materials from the w/p.
• The whole process takes place in vacuum.
• Vacuum environment is used to prevent the contamination and avoid collision of
electrons with air molecules.

Main Parts of EBM-
• Cathode
• Annual Bias Grid
• Anode
• Magnetic Lens
• Electromagnetic Lens
• Deflector coils

Advantages-
• It can produce bolts of small sizes.
• High accuracy and better surface finish.
• Almost all types of materials can be machined.
• Highly reactive metals such as Al and Mg can be machined easily.
• Cost of work holding and fixtures is reduced.

Disadvantages-
• High equipment cost
• Low metal removal rate: The metal from the workpiece is removed at the slower rate.
• High skilled operator: For operating Electron beam machine, A high skilled operator is
required.
• High power consumption: It consumes high power in its operation.
• Not applicable to produce perfectly cylindrical deep holes.

Application-
• Electron Beam Machining is used to produce smaller size holes in various industries like
automobile, aerospace, marine, etc.
• It is also used for making fine gas orifices in space nuclear reactors.
• Used for making turbine blades for supersonic aero engines.

LASER BEAM MACHINING
• INTRODUCTION
•A laser beam machining is a non-
conventional machining method .
•The operation is performed by
laser light.
• The laser light has maximum
temperature strikes on the
workpiece, due to high temp the
workpiece gets melts.
• The process used thermal energy
to remove material from a metallic
surface

Working Principle of laser beam machining
• In this process, the Laser Beam is called monochromatic light.
• The Laser Crystal (Ruby) is in the form of a cylinder as shown in the above Diagram with
flat reflecting ends which are placed in a flash lamp coil of about 1000W.
• The Crystal gets excited and emits the laser beam which is focused on the workpiece by
using the lens.
• The beam produced is extremely narrow and can be focused to a pinpoint area with a
power density of 1000 kW/cm2.
• Produces high heat and the portion of the metal is melted and vapourises.

Main parts of Laser Beam Machining-
• Power Supply
• Flash Lamps
• Capacitor
• Reflecting mirror
• Lens
• Workpiece

Advantages -
• Non Contact
• No solvent chemical
• Selective material removal
• Flexibility
• Fully automated

Disadvantages-
• Requires specially trained operators
• Not for mass metal removal processes
• Requires greater control of joint tolerances
• Expensive equipment
• Consumes much energy

Non conventional Machining processes For B.Tech Mechanical Engineering

PLASMAARC CUTTING
• INTRODUCTION
Plasma Arc Cutting is a thermal
material removal process that is
primarily used for cutting thick
sections of electrically conductive
materials.
Plasma can be defined as a
“superheated, electrically ionized
gas.”

Plasma Arc Cutting Processes-
• PAC uses a high velocity jet of plasma to cut through the metal by melting it.
• The high gas flow rate facilitate the removal of molten metal through the kerf
• Stream pressures can reach up to 1.4 MPa.

Gases used-
• Primary Gases: Gases that are used to create the plasma arc. Examples are
nitrogen, argon, hydrogen, hydrogen, or mixture of them
• Secondary Gases or Water : Surrounds the electric arc to aid in confining
it and removing the molten material.

System Components-
• Torch
• Power Supply
• Arc Starting Circuit

Advantages –
• Cuts any metal.
• 5 to 10 times faster than oxy-fuel.
• 150 mm thickness ability.
• Easy to automate

Disadvantages-
• Large heat affected zone.
• Rough Surfaces
• Difficult to produce sharp corners.
• Smoke and noise.
• Burr often results.

Applications-
• Pipe industry – preparing pipe edges for welding.
• industries for shape cutting

Non conventional Machining processes For B.Tech Mechanical Engineering

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