UCM- UNIT-1-INTRODUCTION AND MECHANICAL ENERGY BASED PROCESSES

1. ME8073 –UNCONVENTIONAL MACHINING
PROCESSES

2. UNIT-I
INTRODUCTION AND
MECHANICAL ENERGY BASED
PROCESSES

3. TOPICS
Unconventional machining Process – Need – classification –
merits, demerits and applications. Abrasive Jet Machining –
Water Jet Machining – Abrasive Water Jet Machining –
Ultrasonic Machining. (AJM, WJM, AWJM and USM).
Working Principles – equipment used – Process parameters –
MRR- Applications.

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. Arrangement of Abrasive Jet
Machining (AJM)
.

47. Abrasive Jet Machining (AJM)

49. Abrasive Jet Machining

50. CONSTRUCTION AND WORKING OF AJM
Construction:
• It consists of mixing chamber, nozzle, pressure gauge, hopper, filter,
compressor vibrating device, regulator, etc.
• The gases generally used in this process are nitrogen, carbon dioxide or
compressed air.
• The various abrasive particles are aluminum oxide, silicon carbide, glass
powder, dolomite and specially prepared sodium bicarbonate Aluminum oxide
(A12,O3,) is a general-purpose abrasive and it is used in sizes of 10, 25 and 50
microns. Silicon carbide (SiC) is used for faster cutting on extremely hard
materials.

51. • It is used in sizes of 25 and 50 microns. Dolomite of 200 grit size is found suitable
for light cleaning and etching Glass powder of diameter 0.30 to 0.60 mm are used
for light polishing and deburring.
• As the nozzle is subjected to a great degree of abrasion wear, it is made up of hard
materials such as tungsten carbide, synthetic sapphire (ceramic), etc., to reduce the
wear rate.
• Nozzles made of tungsten carbide have an average life of 12 to 20 hours whereas
synthetic sapphire nozzle have an average life of 300 hours. Nozzle tip clearance
from work is kept at a distance of 0.25 to 0.75 mm.
• The abrasive powder feed rate is controlled by the amplitude of the vibration of
mixing chamber. A pressure regulator controls the gas or air flow and pressure. To
control the size and shape of the cut, either the workpiece or the nozzle is moved by
a well-designed mechanism such as cam mechanism, pantograph mechanism, etc.

52. Working:
• Dry air or gas (N2, or CO₂) is entered into the compressor through a
filter where the pressure of air or gas is increased.
• The pressure of the air varies from 2 kg/cm² to 8 kg/cm²
• Compressed air or high-pressure gas is supplied to the mixing
chamber through a pipe line. This pipe line carries a pressure gauge
and a regulator to control the air or gas flow and its pressure.
• The fine abrasive particles are collected in the hopper and fed into
the mixing chamber. A regulator is incorporated in the line to control
the flow of abrasive particles.

53. • The mixture of pressurized air and abrasive particles from the mixing chamber
flows into the nozzle at a considerable speed.
• Nozzle is used to increase the speed of the abrasive particles and it is increased
up to 300 m/s.
• This high-speed stream of abrasive particles from the nozzle, impact the
workpiece to be machined. Due to repeated impacts, small chips of material get
loosened and a fresh surface is exposed.
• A vibrator is fixed at the bottom of the mixing chamber. When it vibrates, the
amplitude of the vibrations controls the flow of abrasive particles.

54. • This process is widely used for machining hard and brittle materials, non-
metallic materials (germanium, glass, ceramics and mica) of thin sections.
This process is capable of performing drilling, cutting, deburring, etching
and cleaning the surfaces.
• Abrasive Jet Machining (AJM) process differs from sand blasting process.
AJM is basically meant for metal removal with the use of small abrasive
particles, whereas the sand blasting process is a surface cleaning process
which does not involve any metal cutting.

55. 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)

56. .
.

57. 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

59. .
.
Nozzle
Life
Tungsten
Carbide
Synthetic
Sapphire
12 to 20
Hours
Average of
300 Hours

60. .
• .
The Shape and Size of Cut is controlled by a
movement adjusting mechanism given to
work piece or Tool
Cam Mechanism
Pantograph
Mechanism

61. .
.
Air Pressure
2 Kg/cm2 to 8 Kg/cm2

62. Characteristics
of AJM

63. AJM

64. MRR - PARAMETERS

65. MASS FLOW RATE

66. Abrasive Grain Size
OR

67. Abrasive Grain Size
• The various abrasive particles used in AJM process are aluminum oxide
(A12,O3,). silicon carbide (SiC), glass powder, dolomite and specially
prepared sodium bicarbonate Aluminum oxide is a general-purpose
abrasive and is used in sizes of 10, 25 and 50 microns.
• Silicon carbide is used for faster cutting on extremely hard materials. It is
used in sizes of 25 and 50 microns. Dolomite of 200 grit size is found
suitable for light cleaning and etching Glass powder of 0.30 to 0.60 mm are
used for light polishing and deburring.
• In general, larger sizes are used for rapid removal rate while smaller sizes
are used for good surface finish and precision as shown in Fig.

68. Gas Pressure

69. Velocity of Abrasive particles

70. Mixing Ratio

71. Stand off Distance

72. Stand of distance

73. .

74. 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

75. 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

76. Application

77. .
WATER JET
MACHINING

78. Introduction

79. Principle

80. PARTS
Pump
Accumulator
Control Valve
Regulating Chamber
Nozzle

81. .
.
Pump or
Intensifier
Used to Increase the water Pressure
Up to 1500 – 4000 N / mm2

82. .
.
Accumulator
Used to Store the water
Used to avoid water Pulsation

83. .
.
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

84. .
.
Regulating
Chamber
Used to Control the flow of water jet to Nozzle

85. WJM

86. PROCESS PARAMETERS

87. MRR

88. MRR

89. MRR

90. .

91. .

92. ADVANTAGES

93. DIS-ADVANTAGES

94. APPLICATION

95. .
.

96. .

97. Hydro-dynamic jet Machining
Abrasive Water jet Machining

98. Hydro-dynamic
jet Machining
Abrasive Water jet
Machining

99. Characteristics of AWJM

100. ULTRASONIC
MACHINING
PROCESS
USM
.

101. .
.
Ultrasonic
Waves of High
Frequency

102. Sound
.INFRA SONIC
WAVES
ULTRA SONIC
WAVES
AUDIBLE
WAVES

103. SUITABLE

104. PRINCIPLE

109. .
Ultrasonic
Generator
Used to convert the current from low
frequency to high frequency

110. Abrasive Slurry

111. .
Transducer
Used to convert
Electrical energy
into Mechanical
Vibrations

112. .
Tool Holder
Made up of Titanium alloy , Monel ,
Aluminium, Stainless steel

113. .
Tool
Material
Low Carbon Material
and Stainless steel
The tool is brazed,
soldered or Fastened
mechanically to the
transducer through a
tool holder

114. Working of USM

115. 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

116. COMPARISON

117. TRANSDUCER

118. TYPES OF TRANSDUCER

119. 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

120. MAGNETOSTRICTIVE TRANSDUCER

121. 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

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

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

124. 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

125. Advantages –
Magnetostrictive Transducer

126. Disadvantages –
Magnetostrictive Transducer

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

128. PIEZOELECTRIC
effect
crystal

129. 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.

130. Circuit

131. Arrangement of the circuit

132. 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

133. Resonance

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

135. CONCENTRATOR or HORN

136. STRAIGHT AND TAPER ROD AS HORN

137. HORN

138. NODAL POINT
CLAMPING

139. FEED MECHANISM

140. .
1. Its high sensitive
2. Compact in size

141. .
1. Feed rate is high

142. MRR
MRR Per unit time

143. Wear Ratio

144. Factors considered for MRR
in USM

145. Grain size of Abrasives

146. 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

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

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

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

150. Process Parameters

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

152. 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

153. Abrasive Material and
Cutting Power
Process Parameters

154. Advantages of USM

155. Disadvantages of USM

156. Applications

157. Recent Development