Unit IV-Unconventional Machining Processes.pptx

COURSE: MACHINING PROCESSS
CODE: A40315
V Semester
Regulation: R-23
G. Pullaiah College of Engineering and Technology
(Autonomous)
Pasupula, Kurnool- 518002
Dr G Praveen Kumar
Assistant Professor
Mechanical Engineering
Prepared by

 Course objectives:
 Gain knowledge on working principle of different metal cutting processes
and familiarize with cutting forces, machining calculations and cutting fluids.
 Make the student learn about principles of lathe and Drilling machines.
 Make the student learn about principles of Grinding and Milling machines.
 To acquire knowledge in the elementary mechanism and machinability of
materials with different Mechanical and Electrical energy-based Machining
Processes.
 To make student familiar with various advanced machining operations.

Course Outcomes (COs)
After the completion of the course, the student will be able to:
A40315.1 - Operation of various machines like lathe, drilling, grinding,
slotting, shaping, milling etc.
A40315.2 - Practical exposure on flat surface machining, milling and grinding
operations.
A40315.3 - Illustrate advanced machining processes, cutting tools and cutting
fluids for a specific material and part features.
A40315.4 - Differentiate Electrical Energy Based machining processes,
mechanism of metal removal, machine tool selection.
A40315.5 - Interpret Electro Chemical machining process, economic aspects of
ECM

Course Syllabus
UNIT I
Elementary treatment of metal cutting theory – Elements of cutting process –
Geometry of single point tool and angles, chip formation and types of chips –
built up edge and its effects, chip breakers. Mechanics of orthogonal cutting –
Merchant‘s Force diagram, cutting forces – cutting speeds, feed, depth of cut,
heat generation, tool life, coolants, machinability –economics of machining.
cutting Tool materials and cutting fluids –types and characteristics.
UNIT II
Engine lathe – Principle of working- specification of lathe – types of lathes –
work holders and tool holders –Taper turning, thread cutting operations and
attachments for Lathes.
Drilling, Boring Machines, Shaping, Slotting and planning machines - Principles
of working, specifications, types, Tools and tool holding devices – operations
performed, machining time calculation.

UNIT III
Milling machine – Principles of working – specifications – classifications of milling
machines – methods of indexing, milling cutters - machining operation, Accessories to
milling machines.
Grinding machine –Theory of grinding – classification– cylindrical and surface grinding
machine – Tool and cutter grinding machine – Grinding wheel specification - types of
abrasives – bonds, Truing and Dressing of wheels. Lapping, Honing and Broaching
machines – comparison of grinding, lapping and honing. Principles of design of Jigs
and fixtures and uses, Classification of Jigs & Fixtures – Principles of location and
clamping –types.
UNIT IV
Mechanical Energy Based Processes: Abrasive Jet Machining, Water Jet
Machining, Abrasive Water Jet Machining, Ultra Sonic Machining – Working Principle,
Description of Equipment, Process Parameters, Metal Removal Rate, Applications,
Advantages and Limitations.
Electrical Energy Based Processes: Electric Discharge Machining – Wire cut EDM -
Working Principles, Process Parameters, Applications Advantages and Limitations.

UNIT V
Chemical and Electro Chemical Energy Based Processes: Chemical Machining
and Electro Chemical Machining – Working Principle, Etchants, Maskants,
Techniques of Applying - Process Parameters, Electro Chemical Grinding,
Electro Chemical Honing, Applications, Advantages and Limitations.
Thermal Energy Based Processes: Laser Beam Machining and Drilling, Plasma
Arc Machining, Electron Beam Machining – Working Principle, Process
Parameters, Applications, Advantages and Limitations.

. Books and References
Text Books:
1. Manufacturing Technology-Kalpakzian- Pearson Seventh edition. (2018)
2. Production Technology by R.K. Jain and S.C. Gupta, Khanna Publishers, 17th edition.
3. Jain V.K., Advanced Machining Processes, 1st Edition, Allied Publishers Pvt. Ltd., New
Delhi, 2007.
4. Jain V.K., Advanced Machining Processes, 1st Edition, published by CRC Press (Taylor & Francis),
September 7, 2022
Reference Books:
1. Pandey P.C and Shan H.S., Modern Machining Processes, 1/e, McGraw Hill, New Delhi,
2007.
2. Modern Machining Processes by Anand Pandey, published by Ane Books Pvt. Ltd, 2019
3. Production Technology by H.M.T. (Hindustan Machine Tools),TMH, 1st edition, 2001
4. Manufacturing Technology Vol II by P.N. Rao, Tata McGraw Hill, 4th edition, 2013
5. Machine Technology Machine tools and operations by Halmi A Yousuf & Harson, CRC
Press Taylor and Francies.
6. Workshop Technology – Vol II, B.S.Raghu Vamshi, Dhanpat Rai & Co, 10th edition, 2013

Chapter :4
Mechanical Energy Based Processes: Abrasive Jet
Machining, Water Jet Machining, Abrasive Water Jet Machining,
Ultra Sonic Machining – Working Principle, Description of
Equipment, Process Parameters, Metal Removal Rate,
Applications, Advantages and Limitations.
Electrical Energy Based Processes: Electric Discharge
Machining – Wire cut EDM - Working Principles, Process
Parameters, Applications Advantages and Limitations.

 Machining – Produces finished products with high degree of
accuracy.
Tradition Machining Processes (like turning, drilling ,milling) use a
sharp cutting tool to remove the from work piece by shear
deformation
.
Introduction to Non Traditional Machining

 Extremely hard and brittle materials or difficult to machine by
traditional machining processes
 The work piece: too flexible or slender to support the cutting or
grinding forces.
 The shape of the part is complex, such as internal and external
profiles, or small diameter holes.
 Surface finish or tolerance better than those obtainable
conventional process.
 Conventional machining involves the direct contact of tool and
work-piece, whereas unconventional machining does not
require the direct contact of tool and work piece.
Need for the development of Nontraditional Machining
Turbine Blade with cooling Holes

 Based on the principle form of energy nontraditional manufacturing process can
be classified in to following groups.
Classification of Nontraditional Machining Processes
Non Traditional
Machining
Processes
Mechanica
l
Processes
Electrochemic
al
Processes
Electrical
Processes
Chemical
Processes
Thermal
Process

16
Mechanical Based Processes
1. Working principles
2. Equipment used
3. Process parameters
4. MRR
5. Variation in techniques used
6. Applications
AJM
WJM
AWJM
USM
 Erosion of work material by a high velocity stream of abrasives and/or fluid.

ABRASIVE JET MACHINING (AJM)
Principle
In Abrasive Jet Machining process, a
high speed stream of abrasive particles mixed with
high pressure air or gas which is injected on the work
piece through nozzle

Principle and working :
 This process consists of directing a stream of fine abrasive
grains, mixed with compressed air or some other gas at high
pressure through nozzle on to the surface of the work piece to be
machined.
 These particles impinge on the work surface at high speed and
the erosion caused by their impact enables the removal of metal.
 The metal removal rate depends up on the flow rate and size of
abrasive particles.

Important Characteristics of AJM:
 Process Parameters : Abrasive flow rate and velocity, nozzle
tip distance, abrasive grain size.
 Material Removal : By impinging abrasive grains at high speed.

Advantages :
1. Low capital investment required.
2. Brittle materials of thin sections may be easily machined.
3. Intricate cavities and holes of any shape can be
machined in materials of any hardness.
4. There is no direct contract between the tool and the work
piece.
5. Normally inaccessible portions can be machined with fairly
good accuracy.

AJM
Applications
To machine hard and brittle materials
Fine drilling and micro welding
Machining of semiconductors
Machining of intricate profiles
Surface etching
Surface preparation
Cleaning and polishing of plastics, nylon and teflon

Abrasive Jet Machining Processes

AJM
Disadvantages
MRR is slow
Soft material cannot be machined
Machining accuracy is poor
Nozzle wear rate is high
Abrasive powder once used can never be used again
Requires some kind of dust collection system
Cleaning is essential after the operation

Water Jet Machining
Principle
 In WJM, the high velocity of water jet comes out of the
nozzle and strikes the material, its kinetic energy is
converted into pressure energy inducing high stress in
the work material. when this exceeds the ultimate shear
stress of the material, small chips of the material get
loosened and fresh surface is exposed.
 Used to cut paper boards, plastics, wood, fiber glass,
leather

Schematic Representation of
WJM

WJM
Process parameters
Material removal rate
Geometry and surface finish of work material
Wear rate of nozzle

WJM
Characteristics
Work material Soft and non-metallic materials
Tool Water or water with additives
Additives Glycerin, polyethylene oxide
Pressure of water 100 to 1000 Mpa
Mass flow rate 8 lit/min
Power 45 KW
MRR 0.6 Cu.m/S
Feed rate 1 to 4 mm/s
Nozzle material Tungsten Carbide, synthetic sapphire
Stand off distance 2 to 50 mm

WJM
Advantages
Water is used as energy medium and hence it is cheap, non-toxic
and easy to dispose
Low operating cost
Low maintenance cost
Work area remains clean and dust free
Easily automated
No thermal damage to work

WJM
Disadvantages
Initial cost is high
Noisy operation
Difficult to machine hard material

Abrasive Water Jet Machining
Principle:
 In the Abrasive Water Jet Machining (AWJM) process, a high-
velocity stream of abrasive particles is mixed with pressurized water
and directed through a nozzle onto the workpiece. This jet is used to
cut, shape, and remove material from various types of materials,
including hard metals, ceramics, and composites.
 The process involves high-pressure water being forced
through a nozzle where abrasive particles, such as garnet
or aluminum oxide, are introduced. This high-velocity
abrasive water jet then strikes the workpiece, eroding
material through mechanical action to create precise, burr-
free, and intricate cuts without generating significant heat
.

Abrasive Water Jet Machining Processes

Advantages of Abrasive water jet cutting
 No heat-affected zone (HAZ): As it is a cold cutting process, there is no
thermal distortion or change in material properties.
 Can cut any material: Suitable for metals, ceramics, glass, composites,
and even reflective or heat-sensitive materials.
 High precision and accuracy: Provides smooth, burr-free edges with
minimal finishing required.
 Environmentally friendly: Uses water and natural abrasives, producing
minimal hazardous waste.
 No tool wear: Since there is no physical contact between tool and
workpiece, tool wear is eliminated.
 Minimal material wastage: The narrow kerf width results in efficient use
of material.
 Capability for complex shapes: Can easily cut intricate profiles and
patterns.

Disadvantages of Abrasive water jet cutting
 High operating cost: Abrasives and maintenance of high-pressure
pumps are expensive.
 Slow cutting speed: Slower compared to processes like laser or
plasma cutting for some materials.
 Noisy operation: The process generates high noise levels during
cutting.
 Abrasive disposal issues: Used abrasives and sludge require proper
disposal.
 Limited thickness: Efficiency decreases for very thick materials.
 Surface roughness: The surface finish may vary with cutting speed
and abrasive flow rate.

Ultrasonic Machining
Principle

– In the Ultrasonic Machining process the material is removed by
micro-chipping or erosion with abrasive particles.
– A slurry of small abrasive particles are forced against the work
piece by means of a vibrating tool and it causes the removal of
metal from the work piece in the form of extremely small chips
– Ultrasonic refers to high frequency – above 20khz

Working :
 The abrasive particle are driven into
the work surface by a tool oscillating
normal to the work surface at high
frequency.
 The tool is made of soft
material, oscillated at frequencies of
order of 20 to 30 kHz with an
amplitude of about 0.02mm.

 It is pressed against the work piece
with a load of a few kg and fed
downwards continuously as the
cavity is cut in the work.
The tool is shaped as the
approximate mirror image of the
configuration of the cavity desired in
the work.
ULTRASONIC MACHINING (USM)

Important Characteristics of USM :
 Tool Materials : Brass and Mild steel.
 Work piece material : hard and brittle materials like
semiconductors, glass and ceramics.
 Process parameters : Frequency, amplitude, grain size,
slurry concentration and feed force.
 Material Removal : Fracture of work material due to
impact of grains.
 Abrasive : Aluminum oxide, silicon carbide and boron carbide.
 Grain size : 100-800 mesh size.
 Gap : 0.2 to 0.5 mm.

Advantages :
1. Noiseless operation.
2. Low metal removal cost.
3. Extremely hard and brittle materials can be easily machined.
4. Operation of the equipment is quite safe.
5. High accurate profiles and good surface finish can be
easily obtained.
6. The machined work pieces are free of stresses.

Disadvantages :
1. High tooling cost.
2. Low MRR.
3. The size of the cavity can be machined is limited.
4. High power consumption.
5. Theinitial equipment cost is higher than the
conventional machine tools.
6. The process is unsuitable for heavy metal removal.
7. It is difficult to machine softer materials.

Applications :
 Several machining operations like turning, threading,
grinding, milling etc.
 Machining of hard to machine and brittle materials.
 Dentistry work – to drill fine holes of desired shape in teeth.
 Tool and die making, specially wire drawing and extrusion
dies.

Electrical Energybased processes
• Electrical energy is directly used to cut
the material to get the final shape and size
– Electrical discharge machining (EDM)
– Wire cut Electrical Discharge Machining (WC
EDM)

Electrical Discharge Machining
(EDM)
• Principle
– Metal is removed by producing powerful electric
spark discharge between the tool (cathode) and
the work material (anode)
– Also known as Spark erosion machining or electro
erosion machining

Why EDM?
• EDM has the following advantages:
• 1. Cavities with thin walls and fine
features can be produced.
• 2. Difficult geometry is possible.
• 3. The use of EDM is not affected by
the hardness of the work material.
• 4. The process is burr-free.

Principle :
 This process involves controlled erosion of
electrically conducting materials by the initiation of
rapid and rupture electrical discharge between the
tool (cathode) and the work piece (anode)
separated by a dielectric fluid mechanism.
ELECTRICAL DISCHARGE MACHINING(EDM)

Working:
 A suitable gap between the tool and the work piece is
maintained to cause the spark discharge.
 The gap can be varied to match the machining conditions
such as MRR.
 As soon as the voltage gradient set up between the tool and
the work piece is sufficient enough to break down the
dielectric medium.
 A conducting electrical path is developed for spark
discharge owing to ionization of the fluid medium and
thereby causes the current flow.

 The temperature of the spot hit by
the spark may rise up to 10,0000C
causing the work surface to melt
and vaporize and ultimately to take
the form of sphere as it is quenched
by the surrounding fluid.
 If the tool is fed downwards,
maintaining the predetermined gap,
the tool shape profile will be
reproduced on the work piece.
 The spark gap generally 0.01 to 0.1 mm.
discharg
e
 Higher gap increases
the energy but decrease the
spark
frequency
.

 The servo control unit is provided
to maintain the predetermined gap.
 It senses the gap voltage
and compares it with the present
value and the difference in voltage
is then used to control the
movement of servomotor to
adjust the gap.
Important Characteristics of
EDM :
 Tool Material : Copper, Brass an
Graphite.
 Work piece material : conducting
materials and alloys.
 Process parameters : Voltage, Capacitance, Spark

Advantages :
1. Machining time is less than the conventional machining
process.
2. Anycompleted shape that can be made on the tool
canbe reproduced on the work piece.
3. Theprocess can be employed for extremely hardened
work pieces.
4. The process can be applied to all electrically conducting
metals and alloys irrespective of their melting points.
5. Brittle and slender work pieces can be machined with
out distortion.
6. Considerably easier and more economical polishing can be
done on the catering type surfaces developed by EDM.
7. Fine hole can be easily drilled.
8. Enables high accuracy on tools and dies, because they can
be machined in as hard condition.

Disadvantages :
1. It can not be applied to non-conducting materials.
2. Power required is very high compared to conventional
machining processes.
3. In some materials surface cracking may be takes place.
4. Sharp corners can not be produced.
5. Low MRR
6. Surface tend to be rough for larger removal rates.

Applications :
1. Very useful in tool manufacturing due to ease with which
hard metals and alloyed can be machined.
2. Re-sharpening of cutting tools and broaches, trepanning of
holes with straight or curved axes.
3. Machining of cavities for dies and re-machining of die
cavities without annealing.

EDM
• Functions of dielectric fluid
– Acts as an insulating medium
– Cools the spark region & helps in keeping the tool
and work piece cool
– Carries away the eroded material along with it
– Maintains a constant resistance across the gap
– Remains electrically non-conductive

WireCutElectrical DischargeMachining (WC-EDM)
• Principle
 Wire Cut Electrical Discharge Machining (WC-EDM) is a non-
conventional process that uses controlled electrical sparks to
erode and cut electrically conductive materials along a
programmed path. A thin, continuously moving wire acts as
one electrode, and a series of sparks between the wire and
the workpiece, submerged in a dielectric fluid, melt and
vaporize the material.
 This process is highly precise, capable of creating complex
shapes, and is often used for hard metals, tool steels, and
advanced composites where conventional machining is
difficult.

WireCut Electrical Discharge Machining (WC-EDM)

W
C EDM
How it works
 Electrical Sparks: A high-frequency voltage is pulsed between a
thin wire electrode and a conductive work piece.
 Dielectric Fluid: The wire and work piece are immersed in a
dielectric fluid, typically deionized water, which acts as an
insulator until the voltage reaches a critical point, creating a
plasma channel and a spark.
 Material Removal: The spark melts and vaporizes a tiny amount
of the workpiece material. The fluid flushes away the molten
particles (debris) as the spark gap is restored.
 Continuous Motion: A CNC system guides the wire along a
programmed path to cut the desired shape, while the wire itself
is continuously fed from a spool to maintain its integrity.

Wire Cut Electro-Discharge
Machining (WC EDM)

W
C EDM
• Applications
– Best suited for production of gears,tools,
dies, rotors, turbine blades and cams
• Disadvantages
– Capital cost is high
– Cutting rate is slow
– Not suitable for large work pieces

Unit IV-Unconventional Machining Processes.pptx

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