INTRODUCTION AND MECHANICAL ENERGY BASED PROCESSES

1. ME -8073
Unconventional Machining Processes

2. Unconventional Machining Processes
2
• UNIT 1 – Introduction and Mechanical
Energy Based Processes
• UNIT II – Thermal and Electrical Energy
Based Processes
• UNIT III - Chemical and Electro-Chemical
Energy Based Processes
• UNIT IV - Advanced Nano Finishing Processes
• UNIT V - Recent Trends in Non-Traditional
Machining Processes

3. UNIT I -INTRODUCTION AND
MECHANICAL ENERGY BASED
PROCESSES
3

4. Conventional Machining Processes
4
• In conventional machining processes, metal is
removed by using some sort of tool which is
harder than the workpiece and it is subjected
to wear.
• Tool and workpiece are in direct contact

5. DEMERITS OF CONVENTIONAL
MACHINING PROCESS

6. UNCONVENTIONAL
MANUFACTURING
PROCESS
6
Non –Traditional Machining Process
or
Un-Conventional Machining Process
Unconventional Forming Process

7. UNCONVENTIONAL MACHINING
PROCESS
7

8. UNCONVENTIONAL FORMING
PROCESS
8

9. Traditional or Conventional Machining
9

10. Metal Cutting Processes
10

11. Abrasive Machining
11
Cylindrical grinding
Flat surface grinding

12. Abrasive Machining
12
Centreless grinding

13. Need for Unconventional Machining
13
• Greatly improved thermal, mechanical and chemical properties of modern materials –
Not able to machine thru conventional methods. (Why???)
• Ceramics & Composites – high cost of machining and damage caused during machining
– big hurdles to use these materials.
• In addition to advanced materials, more complex shapes, low rigidity structures and
micro-machined components with tight tolerances and fine surface finish are often
needed.
• To meet these demands, new processes are developed.
• Play a considerable role in aircraft, automobile, tool, die and mold making industries.

14. Need for Unconventional Machining
14
• Very high hardness and strength of the material. (above 400 HB.)
• The work piece is 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.
• Temperature rise or residual stress in the work piece are undesirable.

15. CLASSIFICATION

16. 16

17. 17
Unconventional Machining Processes -
Classification
Electrical

18. Mechanical Based Processes
18
AJM - Abrasive Jet Machining
WJM – Water Jet Machining
AWJM – Abrasive Water Jet Machining
USM – Ultrasonic Machining

19. 19
Electrical Based Processes
Electrical
EDM - Electrical Discharge Machining
WCEDM - Wire Cut Electrical Discharge Machining

20. 20
Chemical & Electrochemical Based Processes
ECM - Electro –Chemical Machining
ECD - Electro Chemical Deburring
ECG – Electro –Chemical Grinding
ECH – Electro – Chemical Honing

21. 21
Thermal Based Processes
LBM - Laser Beam Machining
PAM – Plasma Arc Machining
EBM - Electron Beam Machining
IBM – Ion Beam Machining

22. Mechanical based Unconventional Processes
22
USM – Through mechanical abrasion in a
medium (solid abrasive particles
suspended in the fluid)
WJM – Cutting by a jet of fluid
AWJM – Abrasives in fluid jet.
IJM – Ice particles in fluid jet.
Abrasives or ice – Enhances
cutting action.

23. THERMAL ENERGY METHODS
23

24. Thermal based Unconventional Processes
24
Thru – melting & vaporizing
Heat Source:
Plasma – EDM and PBM.
Photons – LBM
Electrons – EBM
Ions – IBM
Machining medium:
different for different processes.

25. .
25

26. ELECTRO CHEMICAL ENERGY
METHODS
26
CHEMICAL ENERGY METHODS
These methods involve controlled etching of the work piece material in
contact with a chemical solution

27. Chemical & Electrochemical
based Unconventional Processes
27
CHM – uses Chemical
dissolution action in
an etchant.
ECM – uses Electrochemical
dissolution action in
an electrolytic cell.

28. SELECTION OF MACHINING METHODS
28

29. PROCESS SELECTION
29
Based on the following points
1. Physical Parameters
2. Shapes to be machined
3. Process Capability or Machining Characteristics
4. Economic Considerations

30. Physical Parameters
30

31. Shapes to be
machined
31
.

32. 32
Process Capability
or
Machining Characteristics
1. Material Removal rate
2. Tolerance Maintained
3. Surface Finish
4. Depth of surface
Damage
5. Power required for
machining

33. 33
Process Economy

34. MRR – Material Removal Rate
34

35. Tolerance
35
. Engineering tolerance
is the permissible
limit or limits of
variation in
manufacturing

36. Surface Roughness / Finish
36
. Surface texture is one of the important factors that control
friction and transfer layer formation during sliding.

37. Parts from EDM process
37

38. Wire EDM Process
38

39. Parts from ECM process
39

40. Parts from Abrasive Water jet Machining
40

41. Parts from LASER Beam Machining
41

42. LIMITATIONS
Of
Un Conventional Machining
42
1. More expensive process
2. Low Material Removal Rate (MRR)
3. AJM, CHM , PAM and EBM are not commercially
economical Process

43. ADVANTAGES
of UCM
43
• High Accuracy and surface finish in process
• Less Rejected pieces
• Increase productivity
• Tool material need not be harder than work piece material.
• Easy to machine harder and brittle materials
• There is no residual stresses in the machined material

44. MECHANICAL ENERGY BASED
PROCESSES

45. MECHANICAL ENERGY METHODS
• Abrasive Jet Machining (AJM)
• Water Jet Machining (WJM)
• Ultrasonic Machining (USM)

46. Abrasive Jet Machining (AJM)

48. Abrasive Jet Machining

49. Arrangement of Abrasive Jet
Machining (AJM)
.

50. Construction details
.
Gas
Used
Nitrogen , Carbon di-oxide ,
compressed air
Abrasive Particles
Used
Aluminium oxide
(10,25&50microns)
Silicon Carbide(25&50microns)
Glass Powder , Dolomite and
Specially Prepared sodium
bicarbonate
Nozzle
Tungsten Carbide ,
Synthetic Sapphire (Ceramic)

51. .
.

52. Construction details
• Aluminium oxide (Al2O3 ) - 10 to 50 microns
• Silicon Carbide (SiC) - 25 and 50 Microns
• Glass Powder - 0.3 to 0.6 mm
Abrasive Particle Sizes

54. .
.
Nozzle
Life
Tungsten
Carbide
Synthetic
Sapphire
12 to 20
Hours
Average of
300 Hours

55. .
• .
The Shape and Size of Cut is controlled by a
movement adjusting mechanism given to
work piece or Tool
Cam Mechanism
Pantograph
Mechanism

56. .
.
Air Pressure
2 Kg/cm2 to 8 Kg/cm2

57. AJM

58. MRR - PARAMETERS

59. MASS FLOW RATE

60. Abrasive Grain Size
OR

61. Gas Pressure

62. Velocity of Abrasive particles

63. Mixing Ratio

64. Stand off Distance

65. Stand of distance

66. .

67. Advantages
1. We can cut all kind of materials
2. No heat produced in process , so no thermal damage
3. Very thin and brittle material can be machined
4. Low initial investment
5. Good Surface Finish
6. Intricate holes can be cut in hard and brittle material

68. Dis-Advantages
1. Low MRR
2. Soft Material cannot be machined
3. Machining accuracy is poor
4. Nozzle Wear Rate is High
5. Abrasive Powder cannot be reused
6. Embedding of Abrasive particle in work piece is the high
damage thing in this process
7. It requires Dust Collection System

69. Application

70. Characteristics
of AJM

71. .
WATER JET
MACHINING

72. Introduction

73. Principle

74. PARTS
Pump
Accumulator
Control Valve
Regulating Chamber
Nozzle

75. .
.
Pump or
Intensifier
Used to Increase the water Pressure
Up to 1500 – 4000 N / mm2

76. .
.
Accumulator
Used to Store the water
Used to avoid water Pulsation

77. .
.
Nozzle
Used to Increase the velocity of water jet
Made up of Sintered Diamond, Tungsten Carbide and
Synthetic Sapphire
Nozzle Exit Diameter 0.05 – 0.35mm
Velocity of Water Jet From Nozzle 920 m/s

78. .
.
Regulating
Chamber
Used to Control the flow of water jet to Nozzle

79. WJM

80. PROCESS PARAMETERS

81. MRR

82. MRR

83. MRR

84. .

85. .

86. ADVANTAGES

87. DIS-ADVANTAGES

88. APPLICATION

89. .
.

90. .

91. Hydro-dynamic jet Machining
Abrasive Water jet Machining

92. Hydro-dynamic
jet Machining
Abrasive Water jet
Machining

93. Characteristics of AWJM

94. ULTRASONIC
MACHINING
PROCESS
USM
.

95. .
.
Ultrasonic
Waves of High
Frequency

96. Sound
.INFRA SONIC
WAVES
ULTRA SONIC
WAVES
AUDIBLE
WAVES

97. SUITABLE

98. PRINCIPLE

100. .
Ultrasonic
Generator
Used to convert the current from low
frequency to high frequency

101. Abrasive Slurry

102. .
Transducer
Used to convert
Electrical energy
into Mechanical
Vibrations

103. .
Tool Holder
Made up of Titanium alloy , Monel ,
Aluminium, Stainless steel

104. .
Tool
Material
Low Carbon Material
and Stainless steel
The tool is brazed,
soldered or Fastened
mechanically to the
transducer through a
tool holder

105. Working of USM

106. Transducer
convert the high
frequency
electrical energy
into Mechanical
Vibrations
Oscillator convert the
Low frequency electrical
energy into high
frequency electrical
energy
20 – 30 HZ
Vibrations are
transferred to
tool material
Abrasive Slurry
Passed
Between the
vibrating tool
and work piece
The
refrigeration
system used
to cool the
abrasive
slurry to 5 –
6 Degree
celcius

107. COMPARISON

108. TRANSDUCER

109. TYPES OF TRANSDUCER

110. MAGNETOSTRICTIVE TRANSDUCER
.
Change in length is independent of
the direction of the magnetic field
But depend only on the
magnitude of the field and
Nature of the material

111. MAGNETOSTRICTIVE TRANSDUCER

112. MAGNETOSTRICTIVE TRANSDUCER
LT battery used to
heat the filament
So electrons are
produced
Those electrons
are accelerated
by HT Battery
So AC current
Produced in the
circuit

113. So Rod start
to vibrate
due to
magnetostric
tive effect
This vibrations rod
create Ultrasonic
Waves , which sent out
MAGNETOSTRICTIVE TRANSDUCER

114. MAGNETOSTRICTIVE TRANSDUCER
The Longitudinal Extension
and contraction of the Rod AB
produce an EMF in the coil L2

115. Resonance
Frequency of the
oscillatory circuit
Frequency of Vibrating
Rod
=
Resonance will occur when
At resonance , the rod vibrates vigorously and ultrasonic
waves are produced at high frequencies

116. Advantages –
Magnetostrictive Transducer

117. Disadvantages –
Magnetostrictive Transducer

118. PIEZOELECTRIC TRANSDUCER
Its more efficient than magnetostrictive transducer
The modern USM are of this type.

119. PIEZOELECTRIC
effect
crystal

120. Definition - Piezoelectric
• Piezoelectric transducers are a type of electro
acoustic transducer that convert the electrical
charges produced by some forms of solid
materials into energy.
• The word "piezoelectric" literally means
electricity caused by pressure.

121. Circuit

122. Arrangement of the circuit

123. Working LT battery used to
heat the filament
So electrons are
produced
Those electrons are
accelerated by HT Battery
So AC current
Produced in the
circuit
This AC current Passes
through L1 and L2 and
its transferred to
Secondary circuit
This AC current passed to the plates A and B and it make the
Crystal to vibrate due to the principle of inverse piezoelectric
effect. The vibrations of crystal creates Ultrasonic waves

124. Resonance

125. Advantages – Piezoelectric transducer
Disadvantages – Piezoelectric transducer
1. Piezoelectric quartz is high cost
2. Cutting and shaping of crystal is very complex.

126. CONCENTRATOR or HORN

127. STRAIGHT AND TAPER ROD AS HORN

128. HORN

129. NODAL POINT
CLAMPING

130. FEED MECHANISM

131. .
1. Its high sensitive
2. Compact in size

132. .
1. Feed rate is high

133. MRR
MRR Per unit time

134. Wear Ratio

135. Factors considered for MRR
in USM

136. Grain size of Abrasives

137. Abrasive material
It Depend on
1.The type of material to be machined
2. Requirement of Surface finish
For Machining - Tungsten Carbide
- Die Steel
Boron Carbide
Silicon Carbide
Abrasives
For Machining - Glass
- Ceramics
Aluminium oxide

138. Concentration of Slurry
Abrasive Slurry = Abrasive Particles + Water

139. Amplitude of Vibration
MRR increase with the increase of Amplitude of Vibration

140. Frequency
MRR increases with the increase of Ultrasonic wave
Frequency

141. Process Parameters

142. Tool Material
Lengthy tool causes overstresses
So tool should be short and rigid
Process Parameters

143. Process Parameters
Wear Ratio
1.5 : 1 For Tungsten Carbide Work Pieces
100 : 1 For Glass Work Pieces
50 : 1 For Quartz Work Pieces
75 : 1 For Ceramics
1 : 1 For Hardened tool steel Work Pieces

144. Abrasive Material and
Cutting Power
Process Parameters

145. Advantages of USM

146. Disadvantages of USM

147. Applications

148. Recent Development

149. UNIT-3
ELECTRICAL ENERGY BASED
PROCESSES

150. .

151. Specifications
Voltage = 250 V
GAP = 0.005 – 0.05 mm
Temperature = 10000 degree celcius
Spark occur = 10 – 30 micro seconds
Current density = 15 – 500 A